Unit One: Cell Biology. National 4/5 Biology Course Unit 1 National 4/5 Units: Cell Biology – now...
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Transcript of Unit One: Cell Biology. National 4/5 Biology Course Unit 1 National 4/5 Units: Cell Biology – now...
![Page 1: Unit One: Cell Biology. National 4/5 Biology Course Unit 1 National 4/5 Units: Cell Biology – now till October Multicellular Animals – October – Feb Life.](https://reader038.fdocuments.us/reader038/viewer/2022110209/56649dea5503460f94ae5679/html5/thumbnails/1.jpg)
Unit One: Cell Biology
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National 4/5 Biology Course Unit 1
National 4/5
Units:• Cell Biology – now till October• Multicellular Animals – October – Feb• Life on Earth – February - April
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National 4/5 Biology Course Unit 1
How is the course assessed?
• Course work:– 3 end of unit tests (one for each unit) –
can have resits if necessary– One Practical investigation– One mini research project (100 words)– One LARGE research project (Added
Value) (500-800 words)– NATIONAL 5 – Final exam!
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National 4/5 Biology Course Unit 1
Work
Classwork to be done in jotter. Remember it every day!
You will get set homework sometimes – but expected to learn the work done each day as you go along!!!
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National 4/5 Biology Course Unit 1
What is in Unit One?
• Cell Biology:– Cell Structure– Transport across membranes– Producing new cells– DNA and protein production– Genetic engineering– Proteins and enzymes– Aerobic respiration– Photosynthesis
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1: Cell Structure
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4/5 Label an animal cell – Cell membrane, cytoplasm and nucleus
4/5 Label a plant cell – Cell wall, cell membrane, cytoplasm, nucleus, chloroplast and vacuole
4/5 State the function of all the parts of animal and plant cells listed above
5 Identify the mitochondria and ribosomes in a cell diagram
5 Explain the function of a mitochondria and a ribosome
5 Label a bacterial cell and explain the differences between it and other types of cell.
5 Label a fungal cell and explain the differences between it and other types of cell.
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National 4/5 Biology Course Unit 1
Cell Structure
Cells are the building blocks of all life.
Cells video
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National 4/5 Biology Course Unit 1
Cell StructureWe will be looking at 4 different cell types:-
• Animal cells• Plant cells• Bacterial cells, and • Fungal cells.
You have already looked at the basic structure of animal and plant cells in S1- S3. We will be looking at all of these cells in greater detail.
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National 4/5 Biology Course Unit 1
What can you remember from last year?
Task One: Complete the revision worksheet on cells.
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National 4/5 Biology Course Unit 1
Cell Structure
Task 2: Prepare slides for examination under a light microscope.
Using the help sheets provided prepare one type of slide – cheek cell, onion cell or Elodea pondweed. After you have examined your own slide share your slide with a group that has prepared a different slide . You should look at all 3 cell types.
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National 4/5 Biology Course Unit 1
Cheek Cells
These are cheek cells viewed at 100x magnification using a light microscope.
http://www.stancoe.org/patterson/cms/staff/humancheekcellwebpage.htm
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National 4/5 Biology Course Unit 1
Onion Skin Cells
These are onion skin cells viewed at 40x magnification using a light microscope.
http://www.baileybio.com/plogger/images/biology/lab_-_plant___animal_cells/onion_cells.jpg
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National 4/5 Biology Course Unit 1
Elodea Pondweed CellsThese are Elodea pondweed cells viewed at 100x magnification using a light microscope
http://seys-science.wikispaces.com/elodea+g
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National 4/5 Biology Course Unit 1
Cell StructureWe will now look in more
detail at the structure of animal and plant cells.
To see more detail or the ultra structure of cells we need to use and electron microscope.
Image from Wikipedia commons http://en.wikipedia.org/wiki/File:Electron_Microscope.jpg
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National 4/5 Biology Course Unit 1
Cell Structure - Organelles
Organelle is the name given to the structures found inside the cell e.g. Nucleus, vacuole, chloroplasts etc.
You need to know about 2 more organelles.
Mitochondria and Ribosomes
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National 4/5 Biology Course Unit 1
MitochondriaMitochondria are the power houses of
cells. They convert energy into forms that are usable by the cell. They are found in the cytoplasm and are the sites of cellular respiration which generates fuel for the cell's activities.
Mitochondria are found in the cytoplasm of the cell.
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National 4/5 Biology Course Unit 1
Electron microscope image of a mitochondrion
(credit: Tom Deerinck and Jeff Martell/MIT)
http://people.eku.edu/ritchisong/ritchiso/mitochondrion2.gif
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National 4/5 Biology Course Unit 1
RibosomesRibosomes can be found
floating free in the cytoplasm or attached to another type of organelle called Rough Endoplasmic Reticulum or R.E.R. for short. (you don’t have to know about R.E.R!)
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National 4/5 Biology Course Unit 1
http://bioweb.uwlax.edu/genweb/molecular/theory/translation/ribosome.jpg
http://www.cbv.ns.ca/bec/science/cell/page11a.gif
Electron Microscope image of ribosomes.
Ribosomes are responsible for
protein synthesis, i.e. this is where
amino acids are assembled into
proteins.
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National 4/5 Biology Course Unit 1
Cell Structure – Organelles
Task 3 – Collect the diagram sheets of the animal cell and the plant cell. Label any structures you recognise.
You will need to include:- Cell membrane, nucleus, cell wall, vacuole, chloroplast, cytoplasm, ribosome and mitochondria.
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National 4/5 Biology Course Unit 1
Animal Cell Diagram
Nucleus
MitochondrionRibosomes
Cell Membrane
Cytoplasm
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National 4/5 Biology Course Unit 1
Plant Cell Diagram
VacuoleChloroplastNucleus
Ribosomes Mitochondria
Cell Wall
Cell MembraneCytoplasm
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National 4/5 Biology Course Unit 1
Cell Structure - Organelles
Task 4 – Collect and complete the worksheet :–
Cell structures and functions.
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National 4/5 Biology Course Unit 1
Bacterial Cells
“For the first half of geological time our ancestors were bacteria. Most creatures still are bacteria, and each one of our trillions of cells is a colony of bacteria.”
Richard Dawkins
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National 4/5 Biology Course Unit 1
BacteriaTThey are the oldest living organisms on earth. They are everywhere. We find them on and in the human body, in the air we breathe, on the surfaces we touch, in the food we eat. Almost 99% of these bacteria are helpful, whereas the remaining are the notorious ones. Some are essential for proper growth of other living beings. They are either free-living or form a symbiotic relationship with animals or plants.
http://en.wikipedia.org/wiki/File:Gram_Stain_Anthrax.jpg
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National 4/5 Biology Course Unit 1
Bacteria
Task 1 : Using the information cards, list the helpful and harmful bacteria with a brief description of why they are useful or what disease they cause.Bacteria Helpful of harmful Why are they useful
or what disease do they cause?
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National 4/5 Biology Course Unit 1
Structure of BacteriaBacteria can occur in different shapes.
However their basic structure is the same.
Task 2: Collect the bacterial cell diagram handout and the information sheet.
Use the information to complete the labels on the diagram and to complete the table.
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National 4/5 Biology Course Unit 1
Capsule
Genetic material
Cell Wall
Plasmid
Cell Membrane
Cytoplasm
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National 4/5 Biology Course Unit 1
Structure Function and importance
Capsule
Cell Wall
Cell Membrane
Genetic Material
Plasmid
Cytoplasm
Provides additional protection from the environment
It strengthens and supports the cellControls the movement of substances into and out of the cell
Made of DNA and controls the activities of the cell
Circular genetic material. Can convey special abilities, e.g. a resistance to certain antibiotics. They can be manipulated by man to produce bacterial cells that produce useful products e.g. Insulin, hormones and enzymes.Most chemical processes take place here controlled by enzymes
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National 4/5 Biology Course Unit 1
Fungal CellsFungi are one of the most important
groups of organisms on the planet. They are important in an enormous variety of ways: -
Task 3: Listen and take brief notes to produce a spider diagram of the importance of fungi.
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National 4/5 Biology Course Unit 1
Recycling
Fungi, together with bacteria, are responsible for most of the recycling of nutrients returning dead material to the soil in a form in which it can be reused. Without fungi, these recycling activities would be seriously reduced.
http://commons.wikimedia.org/wiki/File:Chanterelle_Cantharellus_cibarius.jpg
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National 4/5 Biology Course Unit 1
Fungi are vitally important for the good growth of most plants, including crops. They do this through the development of mycorrhizal associations which help plants obtain more nutrients from the soil.
Mycorrhizae and plant growth
http://en.wikipedia.org/wiki/File:Mycorrhizal_root_tips_(amanita).jpg
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National 4/5 Biology Course Unit 1
FoodFungi are also important directly as food for
humans. Many mushrooms are edible and different species are cultivated for sale worldwide. Fungi are also widely used in the production of many foods and drinks. These include cheeses, beer and wine, bread, some cakes, and some soya bean products.
http://en.wikipedia.org/wiki/File:Asian_mushrooms.jpg
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National 4/5 Biology Course Unit 1
MedicinesPenicillin, perhaps the
most famous of all antibiotic drugs, is derived from a common fungus called Penicillium. Many other fungi also produce antibiotic substances, which are now widely used to control diseases in human and animal populations.
Photo by: Dr. David Midgley Cultures: Dr. David Midgley University of Sydney, Australia.
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National 4/5 Biology Course Unit 1
BiocontrolFungi such as the Chinese caterpillar
fungus, which parasitise insects, can be extremely useful for controlling insect pests of crops. The spores of the fungi are sprayed on the crop pests which then infect the insect resulting in its death. Fungi have also been used to control Colorado potato beetles, spittlebugs, leaf hoppers and citrus rust mites. This method is generally cheaper and less damaging to the environment than using chemical pesticides.
Author : L. Shyamal http://upload.wikimedia.org/wikipedia/commons/9/94/CordycepsSinensis.jpg
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National 4/5 Biology Course Unit 1
Crop Diseases
Fungal parasites may be useful in biocontrol, but they can also have enormous negative consequences for crop production. Some fungi are parasites of plants. Most of our common crop plants are susceptible to fungal attack of one kind or another. Spore production and dispersal is enormously efficient in fungi and plants of the same species crowded together in fields are ripe for attack. Fungal diseases can on occasion result in the loss of entire crops if they are not treated with antifungal agents.
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National 4/5 Biology Course Unit 1
Animal DiseaseFungi can also parasitise domestic animals causing
diseases, but this is not usually a major economic problem. A wide range of fungi also live on and in humans, but most coexist harmlessly. Athletes foot and Candida infections are examples of human fungal infections.
Author:James Heilman, MD http://en.wikipedia.org/wiki/File:FeetFungal.JPG
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National 4/5 Biology Course Unit 1
Food SpoilageIt has already been noted that fungi play a major
role in recycling organic material. The fungi which make our bread and jam go mouldy are only recycling organic matter, even though in this case, we would prefer that it didn't happen! Fungal damage can be responsible for large losses of stored food, particularly food which contains any moisture. Dry grains can usually be stored successfully, but the minute they become damp, moulds are likely to render them inedible. This is obviously a problem where large quantities of food are being produced seasonally and then require storage until they are needed.
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National 4/5 Biology Course Unit 1
Structure of a fungal cell
Task 4: Collect the diagram sheet and label any of the structures and organelles you recognise.
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National 4/5 Biology Course Unit 1
Structure of a fungal cell
Cell Wall
Cell Membrane Vacuole
CytoplasmNucleus
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National 4/5 Biology Course Unit 1
All the cell parts are now familiar. You should be able to compare all the cell types and identify which parts are similar and which are not. While all the cell parts have the same functions as before there is one difference.
The fungal cell wall.
Just as the bacterial cell wall has a different chemical structure from a plant cell wall, so does the fungal cell wall.
The fungal cell wall is made from a chemical called chitin.
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National 4/5 Biology Course Unit 1
It is important that you know
The cell walls in plant, bacterial and fungal cells is structurally and chemically different.
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National 4/5 Biology Course Unit 1
Homework
Collect the homework sheet :-
Cell Structure – Review Homework
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2. Transport across cell membranes
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4/5 Describe the structure of the cell membrane
4/5 Explain what happens during diffusion
4/5 Explain what happens during osmosis
5 Describe the effects of different water concentrations on animal and plant cells
5 Explain the difference between passive and active transport
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National 4/5 Biology Course Unit 1
Cell membrane
•The thin, flexible cell membrane enclosing the cell contents controls which substances may enter and leave the cell.
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National 4/5 Biology Course Unit 1
•The cell membrane (or plasma membrane) is made up of a bilayer of lipids with protein scattered throughout and is selectively permeable.
•Proteins can;– be attached to the surface– be embedded within the bilayer– span the whole bilayer– form channels in the lipid bilayer
The Cell Membrane
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
•Small molecules can pass through pores in the membrane made by channel forming proteins and enter or leave the cell. This is why the plasma membrane is selectively permeable.
• This transport of molecules is passive and requires no energy as it is with the concentration gradient.
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National 4/5 Biology Course Unit 1
•When molecules in gases or liquids are unevenly distributed we say that a concentration gradient exists.
•Because the molecules are constantly moving around they tend to distribute themselves evenly, i.e. they always move from an area of high concentration to an area of low concentration, down the concentration gradient.
Concentration Gradients
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National 4/5 Biology Course Unit 1
High
Low
Con
cent
ratio
n
Area 1 Area 2
Molecules move down the concentration gradient
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National 4/5 Biology Course Unit 1
•Teacher demonstration of diffusion
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National 4/5 Biology Course Unit 1
•Diffusion is the name given to this movement of the molecules of a substance from a region of high concentration of that substance to a region of low concentration of that substance until the concentration becomes equal.
Diffusion
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National 4/5 Biology Course Unit 1
• Cut a 20cm piece of visking tubing and tie a knot in one end.
• Soak the tubing in water and never let it dry out during the experiment.
• Fill the visking tubing with 5-10cm3 starch and glucose solution and seal with another knot.
• Place this in a boiling tube of water completely submerged and leave until the next lesson.
Diffusion Activity
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National 4/5 Biology Course Unit 1
Take a small sample of the water from around the test tube. Test for starch and sugar
Test for
starch
1. Put sample on tray
2. Add 4 drops of IODINE
3. If starch is present it goes from brown to black
Test for
sugarBOILING WATER
1. Put sample in test tube – IN a beaker of BOILING WATER
2. Add 4 drops of BENEDICTSSOLUTION
3. If sugar is present it goes from blue to orange
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National 4/5 Biology Course Unit 1
•Perform Benedict’s test and starch test on the water in the boiling tube from Diffusion in a Model Cell experiment you set up last lesson.
•Explain your results in terms of diffusion. (LO1 assessment).
Activity
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National 4/5 Biology Course Unit 1
Importance of diffusion to cells
In an animal cell, food (such as glucose), oxygen and carbon dioxide will diffuse like this:
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National 4/5 Biology Course Unit 1
GlucoseOxygen
Carbon dioxide
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National 4/5 Biology Course Unit 1
Substances which diffuse in or out of cells
Diffuse IN Diffuse OUT
Oxygen (raw material for respiration)
Carbon dioxide (waste from respiration)
Carbon dioxide (PLANTS ONLY, raw material for
photosynthesis)
Oxygen (PLANTS ONLY, made in photosynthesis)
Glucose (raw material for respiration)
Urea (a cell waste product)
Amino acids (raw materials to build the cell)
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National 4/5 Biology Course Unit 1
Osmosis: the diffusion of water
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National 4/5 Biology Course Unit 1
•The diffusion of water through a selectively-permeable membrane from an area of high concentration of water molecules to an area of low concentration of water molecules is called osmosis.
Osmosis
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National 4/5 Biology Course Unit 1
Osmosis words
Isotonic – same water concentration.
Hypotonic – High water concentration e.g.. Pure water
Hypertonic – Low water concentration e.g. water with sugar and salt dissolved in it.
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National 4/5 Biology Course Unit 1
Effects of Osmosis on Plant Cells
Cells in a dilute/ hypotonic solution become turgid
Cells in the same/ isotonic solution stay the same.
Cells in concentrated/ hypertonic solutions become flaccid.
Plasmolysed cell – cytoplasm is pulled away from the cell wall.
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National 4/5 Biology Course Unit 1
Turgid Cells•Osmosis makes plant cells
swell. Water moves into the plant cell vacuole and pushes against the cell wall. The cell wall stops the cell from bursting. We say that the plant is turgid. This is useful as it gives plant stems support.
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National 4/5 Biology Course Unit 1
Flaccid Cells• If a plant lacks water, it wilts
and the cells become flaccid as water has moved out of the cell. If alot of water leaves the cell, the cytoplasm starts to peel away from the cell wall. We say the cell has undergone plasmolysis.
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National 4/5 Biology Course Unit 1
Osmosis in Animal Cells
Cell placed in distilled water/hypotonic solution
Cell placed in concentrated/hypertonic solution
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National 4/5 Biology Course Unit 1
•Active transport is the movement of molecules across a cell membrane from a low to a high concentration i.e against a concentration gradient.
•Active transport works in the opposite direction to the passive transport of diffusion and always requires energy.
•This energy is released during respiration.
Active Transport
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National 4/5 Biology Course Unit 1
ENERGY
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National 4/5 Biology Course Unit 1
•Active transport carriers are often called pumps.
•In this example, the same carrier molecule actively pumps sodium ions out of the cell and potassium ions into the cell, each against a concentration gradient.
•Video clip
Sodium/potassium pumps
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3. Producing New Cells
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4/5 Describe what happens during mitosis
4/5 Explain what the chromosome complement is and why it important that it is maintained
4/5 Explain how mitosis (cell cycle) is controlled and how this can lead to cancer
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National 4/5 Biology Course Unit 1
Everyone in this room started life as a single cell, a fusion of
a sperm and egg cell.
What processes must have happened to develop you
from that single cell?
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National 4/5 Biology Course Unit 1
How many new cells do you think you will make in
a day?Cell Division throughout Life
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National 4/5 Biology Course Unit 1
330 000 000 in 20 minutes so…
23,760,000,000 new cells every day!
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National 4/5 Biology Course Unit 1
What do these pictures all have in common?
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National 4/5 Biology Course Unit 1
They are all examples of Cell Division in action for growth
or repair!
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National 4/5 Biology Course Unit 1
How do Cells Divide?
Mitosis – watch this clip on the process of mitosis and answer the following questions:1.How are new cells produced?2.What are chromosomes? Where are they found?3.What kind of cells undergo mitosis?4.What are the only kind of cells that do not undergo mitosis?
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National 4/5 Biology Course Unit 1
Put the following stages of mitosis in the correct order:
• New nuclear membranes form around the chromosomes, followed by new cell membranes, creating two new identical cells.
• Chromosomes replicate to form identical chromatids.
• Spindle fibres then pull the matching chromatids apart, to opposite poles of the cell.
• The membrane around the nucleus breaks down, and spindle fibres attach to the chromatids and line them up in the centre of the cell - equator.
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National 4/5 Biology Course Unit 1
Why do chromosomes need to be copied so carefully and put into
each new cell?• Chromosomes carry GENES, which are
stretches of DNA. • Each GENE codes for one protein e.g.
one gene codes for haemoglobin, the substance in red blood cells that carries oxygen. Other genes will code for other molecules that make up the body.
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National 4/5 Biology Course Unit 1
Chromosome Complement
• The number of chromosomes that a species of animal or plant possesses.
• Why so you think it is important that each new cell has the same chromosome complement as the parent cell?
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National 4/5 Biology Course Unit 1
• During growth and development of an organism will be able to provide the animal or plant with all the characteristics of its species.
• Losing any chromosome would mean a loss of genetic information – the information that forms the code allowing the cell to function correctly!
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National 4/5 Biology Course Unit 1
The Cell Cycle
Second Growth Phase
First Growth PhaseDNA
Synthesis
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National 4/5 Biology Course Unit 1
What happens in each phase?
• First Growth Phase - Cell grows and increases in mass by adding cytoplasm, cell membrane and cell wall (if it is a plant). The materials needed for DNA replication are made.
• DNA Synthesis phase – DNA is replicated. We’d see the chromosomes replicate and become chromatids.
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National 4/5 Biology Course Unit 1
• Second Growth Phase - It’s another period of growth. The cell builds up an energy reserve to last it through the rest of the process and proteins necessary for cell division are made.
• Mitosis Phase – Mitosis takes place and cell divides.
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National 4/5 Biology Course Unit 1
Need for Checkpoints
• We know that it is important that each new cell produces is identical to the parent cell and can perform the same function.
• The cell self checks at THREE stages to make sure that it is ready to proceed.
• If the cell is not ready then it should not proceed to the next stage and if there is something wrong then the cell should not divide at all but should be destroyed!
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National 4/5 Biology Course Unit 1
The Cell Cycle
Second Growth Phase
First Growth PhaseDNA
Synthesis
Checkpoint One
Checkpoint Two
Checkpoint Three
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National 4/5 Biology Course Unit 1
What are the checkpoints?• End of First Growth Phase. Checking the Cell
Size – is the cell big enough to continue? Yes – go to S phase!
• End of Second Growth Phase. Has the DNA been copied correctly? Is DNA replication complete? Has the cell enough energy/materials to continue. Yes – can enter mitosis!
• During mitosis, have the chromatids been pulled apart correctly? Then the cell can divide!
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National 4/5 Biology Course Unit 1
What would happen if the controls failed?
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National 4/5 Biology Course Unit 1
What goes wrong in Cancer?
1 1 1
11
11
2
2222 2222
22
2 3 33 33
333
3
333
3
33
33
33
33
3
3
3
4
44 4
44
44
44 44 4
4
4 44
444
54
44 5
5
55
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5 555
55
55
55
55
555555
5
Increased cell division = more cells
Decreased cell death = more cells
Loss of contact inhibition – the cells no longer stay in one place
Ability to invade surrounding tissues
Ability to move - metastasis
Loss of DNA Repair
Escape from immune surveillance = cells not destroyed
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National 4/5 Biology Course Unit 1
Cancer cells – Research Task1. Find out the meaning of the following terms…
• Benign• Malignant• Metastasis2. Research a type of cancer and find out the
following:• What part of the body does this cancer affect?• What are the clinical symptoms?• How common is this cancer (in the UK)?• What is the treatment given for this cancer?• What research is being done on this cancer? • Is there a charity fundraising to help support
people affected by this type of cancer?
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4. DNA and Protein Production
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4/5 Explain what is meant by DNA, genes and chromosomes
5 Describe structure of a nucleotide
5 State the letters which identify the 4 different bases and how they pair up
5 Explain how the genetic code works
4/5 Explain the structure of proteins
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National 4/5 Biology Course Unit 1
What is DNA?
Watch the following video that introduces DNA and its importance.
DNA video
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National 4/5 Biology Course Unit 1
DNA, genes and chromosomes
ChromosomesThe cell’s nucleus contains chromosomes made from long DNA molecules.
DNADNA molecules are large and complex. They carry the genetic code that determines the characteristics of a living thing.
GenesThink back to the last section!
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National 4/5 Biology Course Unit 1
DNA, genes and chromosomes
The diagram shows the relationship between the cell, its nucleus and the chromosomes in the nucleus that are made up of DNA, and genes.
DNA
Collect the handout sheet and stick it into your jotters.
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National 4/5 Biology Course Unit 1
From Genes to Proteins?
Watch the following video that gives a basic definition of a gene and what genes do.
What exactly is a gene?
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National 4/5 Biology Course Unit 1
DNA Structure
DNA consists of two molecules that are arranged into a ladder-like structure called a Double Helix.
A molecule of DNA is made up of millions of tiny subunits called Nucleotides.
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National 4/5 Biology Course Unit 1
Nucleotide Structure
Each nucleotide consists of:
PhosphateGroup
DeoxyriboseSugar
OrganicBase
Copy this diagram into your jotters.
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National 4/5 Biology Course Unit 1
DNA StructureThe phosphate and
sugar form the backbone of the DNA molecule, whereas the bases form the “rungs”. Collect the handout and stick it into your jotters.
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National 4/5 Biology Course Unit 1
The Genetic CodeThe genetic code determines the order in
which amino acids are joined together to produce a specific protein.
The code itself is determined by the order of the organic bases in the DNA molecule.
There are 4 different bases.
Guanine Cytosine Adenine and Thymine
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National 4/5 Biology Course Unit 1
Each base can only join with one other type of base:-
Guanine always pairs with CytosineAdenine always pairs with Thymine
G-Cand A-T
These are called complementary base pairs.
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National 4/5 Biology Course Unit 1
Complementary Base Pairs
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National 4/5 Biology Course Unit 1
Build your own DNA Molecule
Task 1: Collect the handout sheets
DNA origami instructions and template
Follow the instructions to complete your own model DNA!
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National 4/5 Biology Course Unit 1
Protein StructureProteins are made up of amino acids.
The order of the amino acids determines the proteins molecular structure, its shape and its function.
The order of the amino acids is determined by the order of the bases in the DNA molecule – the genetic code.
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National 4/5 Biology Course Unit 1
So how does the genetic code get translated into a protein?
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National 4/5 Biology Course Unit 1
Watch AgainWatch the ‘What is DNA?’ video again. This time try to answer the following questions:- Video
• How is the genetic code from the DNA molecule copied?
• What happens to the copy of the genetic code? Where does it go?
• In which organelle is the copy of the genetic code translated to form proteins?
• How are the proteins formed?
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
Translating the genetic code
Task 1: Using the information in the video, the questions and discussion with your teacher write a short paragraph to describe how the genetic code from the DNA is translated into a protein.
You could use a diagram to help illustrate you description.
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National 4/5 Biology Course Unit 1
Translating the genetic codeThe genetic code in the DNA is copied or transcribed by another molecule called Messenger RNA (mRNA).
The mRNA carries the code out of the nucleus to the ribosomes in the cytoplasm.
The ribosomes then translate the code from the mRNA into the specific protein using amino acids found free in the cytoplasm.
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National 4/5 Biology Course Unit 1
mRNA
The DNA for the gene being turned into a protein is copied into a mRNA molecule.
It is different from DNA, it is:• Shorter• Single stranded• Have URACIL instead of THYMINE.
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National 4/5 Biology Course Unit 1
How does mRNA become a protein
Every 3 letters in the mRNA tell the ribosome which amino acid to add to the protein.
A U G C G A U G G A C G mRNA
Alanine Serine Glycine Proline
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National 4/5 Biology Course Unit 1
Translating the genetic code
Task 3: In groups produce an A4 poster to illustrate protein synthesis.
Your poster should contain the following information:-
• DNA carries the genetic code for producing proteins• mRNA copies the code• mRNA carries the copy of the code to the ribosomes• The ribosomes translate the copy of the code to produce proteins
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National 4/5 Biology Course Unit 1
Glossary of terms
Task 4: Homework – collect the handout
Glossary of Terms – DNA and the production of proteins.
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National 4/5 Biology Course Unit 1
Research Task – Who Discovered DNA?
Your task is to write an essay or newspaper/magazine article that discusses the scientists who played significant roles in the discovery of DNA, its structure and its importance.
You should include:
• James Watson, Francis Crick, Rosalind Franklin, Maurice Wilkins and Erwin Chargaff and any other scientist you think is important.• The importance of the roles they played in the discoveries about DNA, including dates.• Any special recognition they received (or did not receive) for their discoveries
Your work should be at least one side of A4 and should contain some illustrations. Your work should be in your own words and not copied and pasted directly from the web.
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5. Genetic Engineering
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4/5 Describe the process of genetic engineering
4/5 List examples of how genetic engineering has been used
5 Describe what is meant by a GM organism and why it might be controversial
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National 4/5 Biology Course Unit 1
What is genetic engineering?
What is it used for?
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National 4/5 Biology Course Unit 1
Watch the following clip on Genetic Engineering and in pairs answer the following questions:1.What 3 things are produced by genetically modifying microbes?2.Name the first organisms to be genetically modified and when this was done.3.What does insulin normally do? What condition arises from not making insulin?
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National 4/5 Biology Course Unit 1
GMO Defined…• An organism that is generated through
genetic engineering is considered to be a genetically modified organism (GMO).
• The first GMOs were bacteria in 1973; GM mice were generated in 1974. Insulin-producing bacteria were commercialized in 1982 and genetically modified food has been sold since 1994.
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National 4/5 Biology Course Unit 1
The process of Genetic Engineering
• The control of all the normal activities of a bacterium depends upon its single chromosome and small rings of genes called plasmids.
• In genetic engineering pieces of chromosome from a different organism can be inserted into a plasmid. This allows the bacteria to make a new substance.
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National 4/5 Biology Course Unit 1
Task 1 – Use the cut out sheet and put the stages of genetic engineering in the
correct order. Use the following diagram to
help you.
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
Uses of Genetic Engineering 1
Genetic engineering is used for the production of substances which used to be both expensive and difficult to produce. Examples include:•insulin for the control of diabetes•antibiotics such as penicillin•various vaccines for the control of disease•enzymes for laundry detergent
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National 4/5 Biology Course Unit 1
Uses of Genetic Engineering 2
Genetic engineering is a way of producing organisms which have genotypes best suited for a particular function. In the past man has used selective breeding to achieve this. This was done by choosing only his most suitable animals and plants for breeding.
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National 4/5 Biology Course Unit 1
Genetic engineering has several advantages over selective breeding. Some are:
• particular single characteristics can be selected
• the selection may be quicker• a desirable characteristic can be transferred
from one species to another
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National 4/5 Biology Course Unit 1
Genetic Engineering – now and the future?
• It is not just bacteria that can be genetically modified, plants and animals can be modified too.
• It is therefore possible to genetically engineer people!
• It holds the promise of curing genetic diseases like cystic fibrosis, and increasing the immunity of people to viruses.
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National 4/5 Biology Course Unit 1
• It is speculated that genetic engineering could be used to change physical appearance, metabolism, and even improve mental faculties like memory and intelligence, although for now these uses seem to be of lower priority to researchers and are therefore limited to science fiction.
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National 4/5 Biology Course Unit 1
Issues?
• There are dangers involved with genetic engineering since it involves creating completely new strains of bacteria. There is a possibility of creating some which are harmful to animal or plant life.
• What is your opinion on GM Food (plant and animal), GM organisms for research and GM People?
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National 4/5 Biology Course Unit 1
Task 2 – Genetically Engineering the Future
• Thinking about the possibilities and issues surrounding genetic engineering, I want you to imagine 50 years from now. Technology has moved on and GMO is commonplace in agriculture, medicine and all organisms.
• Write a letter to your present self, describing this new world. Be honest in this letter, what are the good and bad points about GMO in the future?
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National 4/5 Biology Course Unit 1
Therapeutic Uses of Cells - HeLa Cell Line
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National 4/5 Biology Course Unit 1
Henrietta Lacks
Listen as your teacher reads out the poem “The Life and Life of Henrietta Lacks” by Carol Satyamurti.
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National 4/5 Biology Course Unit 1
Task 1 – Find out more…using the Fox Thinking Tool
1. In pairs divide the information sheets about Henrietta Lacks and the HeLa Cell Line and spend time reading through them.2. Individually on a piece of paper/card or sticky note write a brief summary of what you have read3. Individually on a second piece of paper/card or sticky note write your opinions of what you have read4. Talk to your partner to exchange findings and ideas about the section you have read. 5. Compare your pairs ideas with the rest of your group/table by carrying out a quick “sweep” of the information that you write down.6. Stick the summaries and opinions on the poster paper to form a “doughnut” or ring shape7. In the middle of “doughnut” give the points (3-5) the group thinks are the most important8. Around the outside give the reasons (3-5) why the group thinks these are most important •You will then be asked to use your work to discuss a Key Question
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National 4/5 Biology Course Unit 1
The story of Henrietta Lacks and the HeLa Cell Line bring up a lot of issues including:
1. Scientific progress and the possibilities of human cloning
2. Scientific ethics (the rights and wrongs in how things are done)
3. The moral and legal aspects of cloning – for example, if you are cloned, will you be you, or something like your own child, or a completely new person?
4. Aspects of social history, relating to – Poverty– Gender– Race
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National 4/5 Biology Course Unit 1
The Key Question to debate:
Should scientists be free to use our cells in scientific
research such as in the case of the HeLa Cell Line?
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National 4/5 Biology Course Unit 1
• Further Reading: The Immortal Life of Henrietta Lacks by Rebecca Skloot.
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6. Proteins and Enzymes
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4/5 Explain what enzymes do and what the main features of an enzyme are
4/5 Give 3 named examples of chemical reactions carried out by enzymes and be able to draw the word equations
4/5 Explain how temperature effects enzyme activity
4/5 Explain how pH effects enzyme activity
4 Describe some uses of enzymes in industry e.g. Biological detergents and rennet in cheese making
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National 4/5 Biology Course Unit 1
Protein structure
• Proteins are made up of sub-units called amino acids.
• There are 21 amino acids.• The order of amino acids in a protein
is dictated by the genetic code.• Every protein has different amino
acids in different orders.
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National 4/5 Biology Course Unit 1
• The order of the amino acids affects the shape of the protein.
• Proteins can be fibrous or globular:• GLOBULAR – enzymes• FIBROUS – keratin (hair)
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
Catalysts
A catalyst speeds up a chemical reaction, but is unchanged in the process and can be used over and over again.
In living things, catalysts are known as enzymes.
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National 4/5 Biology Course Unit 1
If cells did not have enzymes in their cytoplasm, then the chemical reactions which happen in our cells would happen so slowly that life would be impossible!
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National 4/5 Biology Course Unit 1
An example of an enzyme: CATALASE
Hydrogen peroxide (H2O2) is a liquid similar to water (H2O), but with one extra oxygen.
Over a long period of time hydrogen peroxide naturally breaks down into water and oxygen.
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National 4/5 Biology Course Unit 1
The word equation for this reaction is:
Hydrogen peroxide water + oxygen
This process can be sped up using an enzyme.
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National 4/5 Biology Course Unit 1
Into each test tube – measure out 5 ml of Hydrogen peroxide AND 5 drops of
detergent.
CAUTION!!
Hydrogen peroxide is a dangerous chemical.
Safety goggles must
be worn!!
1. Add nothing 2. Potato 3. Carrot 4. Liver
Leave for 10 minutes. Measure the height of the foam bubbles.
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National 4/5 Biology Course Unit 1
Test tube contents Height of foam (mm)
Nothing – “CONTROL”
Potato
Carrot
Liver
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National 4/5 Biology Course Unit 1
Conclusion
Only the plant and animal tissues speed up the breakdown of hydrogen peroxide.
This is because the cells contain catalase. Catalase is an enzyme found in living cells.
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National 4/5 Biology Course Unit 1
CatalaseHydrogen peroxide water +
oxygen
The tissue which contained the most catalase was ______________.
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National 4/5 Biology Course Unit 1
Breakdown and Synthesis
Catalase is an enzyme involved in chemical breakdown.
“Breakdown” means chopping up larger molecules into smaller molecules.
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National 4/5 Biology Course Unit 1
Other enzymes do the opposite – the build large molecules from smaller molecules. This is called synthesis.
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National 4/5 Biology Course Unit 1
An example of a synthesis enzyme: Phosphorylase
Glucose-1-phosphate is a chemical made by plants during photosynthesis. It is stored in plant cells be converting it into a large molecule called starch.
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National 4/5 Biology Course Unit 1
Phosphorylase
PhosphorylaseGlucose-1-phosphate Starch
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National 4/5 Biology Course Unit 1
Substrates and products
The substrate is the substance the enzyme works on.
The product is the substance the enzyme makes.
EnzymeSubstrate Product
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National 4/5 Biology Course Unit 1
Enzyme Substrate Product
Catalase
Phosphorylase
Amylase
Pepsin
Lipase
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National 4/5 Biology Course Unit 1
How enzymes work
Enzymes are made of protein. This protein has a special shape which is unique to each enzyme.
Enzyme Active site
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National 4/5 Biology Course Unit 1
Enzyme
The active site is the correct shape to fit the substrate.
Substrate
Enzyme
Substrate
Turned into the products
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National 4/5 Biology Course Unit 1
Enzyme
Substrate
Other substrates are the wrong shape to fit in the active site of the enzyme.
Therefore the enzyme will only work with one substrate. This is described as being SPECIFIC.
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National 4/5 Biology Course Unit 1
“Specific”
When talking about enzymes, SPECIFIC means that the ENZYME WILL ONLY WORK WITH ONE SUBSTRATE.
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National 4/5 Biology Course Unit 1
One enzyme = one substrate
5 ml Starch 5 ml Starch 5 ml Starch 5 ml Starch
3 ml Water 3 ml Amylase 3 ml Pepsin 3 ml LipasePut in waterbath for 10 minutes. Test all 4 test-tubes with
Benedict’s Solution
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National 4/5 Biology Course Unit 1
Results
Sugar present?
Starch + water
Starch + amylase
Starch + Pepsin
Starch + Lipase
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National 4/5 Biology Course Unit 1
Conclusion
The test-tube containing Starch and Amylase had the most sugar.
This shows that only Amylase can convert starch to sugar.
Amylase is said to be SPECIFIC to starch.
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National 4/5 Biology Course Unit 1
Effect of temperature on enzymes
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National 4/5 Biology Course Unit 1
5 ml Starch 5 ml Starch 5 ml Starch
3 ml Cold Amylase 3 ml Amylase 3 ml 80oC Amylase
Iced water 37oC 80oC
Put in waterbath for 10 minutes. Test all 3 test-tubes with Benedict’s Solution
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National 4/5 Biology Course Unit 1
Temperature Was sugar present?
0 oC
37 oC
80 oC
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National 4/5 Biology Course Unit 1
All enzymes have a temperature at which the work fastest.
This is called the optimum temperature.
In humans the optimum temperature for all enzymes is 37oC.
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National 4/5 Biology Course Unit 1
Enzymes work slowly at cold temperatures.
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National 4/5 Biology Course Unit 1
At very high temperatures enzymes become changed and do not work.
This is called being denatured.
Once an enzyme is denatured it will never work again.
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National 4/5 Biology Course Unit 1
The effect of pH on enzymes
Into all 5 test tubes put 5ml Hydrogen Peroxide and 5 drops of soap
3ml pH1 buffer 3ml pH4 buffer 3ml pH7 buffer 3ml pH9 buffer 3ml pH 14 buffer
LAST: Add 1 cm cylinder of potato to each test tube. Measure height of foam after 10 minutes.
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National 4/5 Biology Course Unit 1
Results
pH Height of foam (mm)
1
4
7
9
14
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National 4/5 Biology Course Unit 1
Conclusion
The optimum pH for the catalase enzyme is pH _______.
All enzymes have a different optimum pH depending on where they are found in the body.
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Uses of enzymes
Yoghurt and cheese making Biological detergents
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National 4/5 Biology Course Unit 1
Yoghurt and cheese
Yoghurt and cheese making depend on the activities of enzymes in bacteria.
Bacteria used lactose sugar in milk as a source of energy.
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National 4/5 Biology Course Unit 1
They make the waste product called lactic acid which makes the milk increasingly acidic and sour tasting.
Lactose energy + lactic acid
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National 4/5 Biology Course Unit 1
• This is another example of fermentation.
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National 4/5 Biology Course Unit 1
1. Yoghurt making• Milk is heated to kill microbes• Special yoghurt bacteria are added• The lactose in the milk is fermented
by the bacteria.• The milk becomes acidic and so it:
– Thickens– Tastes sour
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National 4/5 Biology Course Unit 1
2. Cheese making
The process is similar to yoghurt making, but after the fermentation, rennet is added which curdles the milk.
The solid curds are separated from the liquid whey.
The curds are then pressed into hard cheese.
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National 4/5 Biology Course Unit 1
Task 3 – Note Taking
• The following slides will tell you about biological detergents; how they are made, why they are useful and their environmental impact.
• Your task is to take notes from the slides – this could be mind mapping key words and concepts under the headings above or a table of information or bullet point. Decide quickly which method you find most useful when revising and try it this way.
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National 4/5 Biology Course Unit 1
How Biological Detergents are produced:
• Biological detergents contain enzymes such as protease, amylase and lipase to digest proteins, starch and fats respectively.
• Enzymes can be produced using bacteria that have been genetically engineered to make these enzymes. They are grown in industrial fermenters in vast quantities. This equipment ensures that the bacteria receive food and oxygen so that they grow well. The bacteria will produce the enzymes and pass them out into the culture liquid. The bacteria and the filtered off and the enzymes extracted from the liquid. The enzymes are purified and added to washing powder.
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National 4/5 Biology Course Unit 1
Value and Use of Product:
• Advantages of using biological detergents include reducing fuel costs as clothes can be washed at lower temperatures reducing the electricity consumption; Less damage to delicate fabrics such as acrylic and wool whilst still cleaning effectively and the ability to remove difficult stains such as grass and blood. These will be completely removed by biological washing powder but not by non-biological even at high temperatures.
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National 4/5 Biology Course Unit 1
Environmental Impact 1:
• Reduced Fuel Consumption - using Biological Detergents has a positive impact on our environment as it reduces CO2 and SO2 production from burning fossil fuels in Power Stations to generate electricity.
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National 4/5 Biology Course Unit 1
Environmental Impact 2:
• Detergents are rich in chemicals called phosphates. This chemical passes from waste water from people’s homes to sewage works. Unfortunately it is hard to remove during processing and can end up in local rivers where they cause algal bloom. This single celled plant can overwhelm the balance of the ecosystem and when it dies can cause bacterial numbers to increase. The bacteria use up oxygen in the water which leads to the death of other organisms.
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National 4/5 Biology Course Unit 1
Task 3 – Note Taking
• Your task was to take notes from the slides – it would be useful to check your notes with a peer. Have you covered similar key areas?
• If you are not sure, the check with your teacher!
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National 4/5 Biology Course Unit 1
Task 4 – Write a Newspaper Article
OPTION 1 – Write a newspaper article advocating the Use of Biological Detergents. This should look favourably on their usage, highlighting their value rather than any negative aspect.
OPTION 2 – Write a newspaper article examining the Environmental Impact of Biological Detergents. In this option you should be highlighting why people should not use these and the damage that they can cause.
BE AWARE: Be sure that you justify your argument with facts and do not make up “facts” to suit your argument!
This task has to be completed for homework.
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National 4/5 Biology Course Unit 1
Task• Create a Summary of
Enzymes. This can be done in any format you choose; bullet point notes, mind map, poster. Before you start think about how you learn and what you create should be suited to your learning style – do you need colour? Or pictures? Or real life examples?
• The summary should include information about the following:
• Enzymes are Biological Catalysts
• Enzymes are protein• Enzymes are specific (active
site)• Enzyme activity is affected
by pH and temperature• They have optimum
conditions and can be denatured
• Enzymes are used in a variety of industries including producing detergents and making cheese
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National 4/5 Biology Course Unit 1
Peer Review
• Check your table and summary with a peer to check that you have both covered all the key areas!
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7. Respiration
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4/5 Explain what cells need energy for
4/5 Write the word equation for aerobic respiration
5 Explain what ATP is and draw its structure
5 Explain how ATP is produced in the cell and how many ATP are produced for each molecule of glucose
5 Explain what happens during glycolysis
4/5 Describe what is meant by anaerobic respiration
5 Explain what the products of anaerobic respiration are in humans and yeast
4 Explain how anaerobic respiration can be used to benefit man (fermentation in yeast – breadmaking and brewing)
4 Explain how exercise and training can improve your recovery time
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National 4/5 Biology Course Unit 1
Why do cells need energy?
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National 4/5 Biology Course Unit 1
Respiration
Why do cells need energy?
Living cells need energy to carry out a variety of cell functions.
energy in
living cells
cell growth
muscular contraction
cell division
nerve impulses
building up large molecules
chemical reactions
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National 4/5 Biology Course Unit 1
energy from food
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National 4/5 Biology Course Unit 1
• The three main food groups are _____, ____________, and __________.
• _____ contains the most energy.
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National 4/5 Biology Course Unit 1
Aerobic Respiration
glucose+oxygen +water
carbon dioxide
energy released
Energy in a cell is produced by a chemical reaction called aerobic respiration.
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National 4/5 Biology Course Unit 1
ATP
The energy produced during aerobic respiration is stored in a molecule called ATP (Adenosine triphosphate).
Every molecule of glucose that is “burned” in the cell produces 38 ATP molecules.
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National 4/5 Biology Course Unit 1
ATP structure
ATP is made up of one Adenosine and three phosphates
3 PHOSPHATE GROUPS
ADENOSINE
High Energy Bond
P P P
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National 4/5 Biology Course Unit 1
ATP is made by joining ADP (Adenosine diphosphate) and phosphate.
ADP Pi ATP
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National 4/5 Biology Course Unit 1
• As a molecule to transfer energy in cells
Glucose+
Oxygen
Carbon Dioxide
+Water
Energy
Energy
ATP
ADP+Pi
e.g. Amino Acids
Protein molecul
e
Energy
Energy
RESPIRATION ENERGY TRANSFER
WORK
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National 4/5 Biology Course Unit 1
Respiration should be seen as a series of enzyme controlled reactions in which
• 6-carbon glucose is oxidised (broken down) to form carbon dioxide
• this is accompanied by the synthesis of ATP from adenosine diphosphate (ADP) and inorganic phosphate (Pi).
Glycolysis
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National 4/5 Biology Course Unit 1
2ADP + 2Pi
Pyruvic Acid
Glucose
2ATP
(6C)
(2x3C)
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National 4/5 Biology Course Unit 1
The first stage of respiration is called Glycolysis.
• This process takes place within the cytoplasm.
• does not require oxygen• involves the step by step breakdown of a
6-carbon sugar such as glucose to form two 3-carbon pyruvic acid units
Glycolysis results in a production of 2ATP.
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National 4/5 Biology Course Unit 1
What happens next?
If there is oxygen available ( the normal situation), then the pyruvic acid produced by glycolysis diffuses into an organelle called mitochondrion for further breakdown if oxygen becomes available.
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National 4/5 Biology Course Unit 1
Structure of a Mitochondrion
Outer Membrane
Cristae
Matrix Fluid
Inner Membrane
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National 4/5 Biology Course Unit 1
• Pyruvic acid from glycolysis diffuses into central matrix fluid
• Pyruvic acid is broken down further in the presence of oxygen by a cycle of reactions called the Kreb’s cycle releasing most of the 38 ATP produced during respiration
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National 4/5 Biology Course Unit 1
Anaerobic respiration
• If there is no Oxygen- Anaerobic Respiration occurs.
• Anaerobic respiration occurs in human after heavy exercise.
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National 4/5 Biology Course Unit 1
Pyruvic acid is converted to either(i) Lactic Acid (in animal and bacterial cells)(ii) Ethanol and carbon dioxide (in plant and
fungal cells)
• No further ATP is made – so only the net 2 ATPs are produced.
• In animal cells the Lactic Acid is converted back to Pyruvic Acid when oxygen becomes available.
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National 4/5 Biology Course Unit 1
Complete this summary table
Aerobic respiration
Anaerobic respiration Humans Yeast/Plant
Site in the cell
Number of ATP
Final products
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National 4/5 Biology Course Unit 1
Complete this summary table
Aerobic respiration
Anaerobic respiration Humans Yeast/Plant
Site in the cell
Cytoplasm &
Mitochondria
Cytoplasm Cytoplasm
Number of ATP
38 2 2
Final products
Carbon dioxide &
water
Lactic acid Ethanol & Carbon dioxide
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8. Photosynthesis
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National 4/5 Biology Course Unit 1
Level What you need to be able to do…
4 Explain the importance of plants and give examples of the uses of named plants e.g. food, raw materials and medicines
4/5 Explain the importance of photosynthesis
4/5 Write the word equation for photosynthesis
4/5 Describe how to test a leaf for starch
5 Explain what happens in the first stage (light reaction) of photosynthesis
5 Explain what happens in the second stage (carbon fixation) of photosynthesis
4/5 Label the parts of a leaf
5 Explain the role of the xylem and phloem
4/5 Explain what a limiting factor is
4/5 List the limiting factors for photosynthesis
4 Describe how farmers and gardeners control the limiting factors to ensure healthy plant growth
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National 4/5 Biology Course Unit 1
Photosynthesis Why are plants important?
What is photosynthesis?
What do plants need for photosynthesis?
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National 4/5 Biology Course Unit 1
The importance of plants
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National 4/5 Biology Course Unit 1
Raw materials
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National 4/5 Biology Course Unit 1
Food
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National 4/5 Biology Course Unit 1
Medicines
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National 4/5 Biology Course Unit 1
Photosynthesis
Importance of plants
FOOD RAW MATERIALS MEDICINES
Wheat – for bread Wood – for building
Poppy – pain killers
Grapes – for wine Cotton – for clothes
Foxglove – heart medicine
Sugar cane – for sugar
Flowers – for perfumes
Mint – menthol for cough sweets
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National 4/5 Biology Course Unit 1
Green plants make their own food using light energy
Green plants convert light energy to chemical energy (food) using a green pigment in the leaves called chlorophyll.
Photosynthesis
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National 4/5 Biology Course Unit 1
Carbon Dioxidetaken up from air
Water - from soil
Light energy- from sun
Oxygen givenoff as waste
Glucoseused for energyor stored as starch
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National 4/5 Biology Course Unit 1
This can be summarised by the following equation
Carbon dioxide
Water Light energyChlorophyll
Glucose Oxygen
Raw MaterialsEnergy source
and pigment whichtraps it
ProductsGlucose is used forenergy, stored as
starch or built up intocellulose
Oxygen is waste gas
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National 4/5 Biology Course Unit 1
• Glucose which are used for energy (respiration)
• Storage carbohydrates such as starch - these can be broken down to simple sugars if needed
• Structural carbohydrates such as cellulose - these are used to build the cell wall
What happens to the glucose?
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National 4/5 Biology Course Unit 1
Chloroplast structure
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National 4/5 Biology Course Unit 1
Stages of Photosynthesis biochemistry
• There are two stages of photosynthesis. The equation you have just learned is actually more complex and occurs at two
separate stages.
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National 4/5 Biology Course Unit 1
Stage 1• The first stage is called PHOTOLYSIS.
• This stage involves using energy from the sunlight to split water molecules into
hydrogen and oxygen.
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National 4/5 Biology Course Unit 1
WATER
ENERGY
(ATP)
Oxygen Hydrogen
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National 4/5 Biology Course Unit 1
Light energy
Chlorophyll
Chemicalenergy
ADP + Pi
ATP
Water
Hydrogen + Oxygen
Passed on to second stage
Passed on to second stage
Released to the air as oxygen gas
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National 4/5 Biology Course Unit 1
Stage 2•The second stage is known as the
Carbon Fixation stage•Here the energy and hydrogen from
stage one are used along with the carbon dioxide.
•It is at this stage where glucose molecules are produced.
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National 4/5 Biology Course Unit 1
Hydrogen
Carbon dioxide
ATP ADP + Pi
Glucose
From the first stage
From the first stage
From the air
Enzyme controlled reactions
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National 4/5 Biology Course Unit 1
•This stage is energy consuming so that is where the ATP comes in.
•This stage is also controlled by enzymes.
•Carbon dioxide and hydrogen join to give us glucose
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National 4/5 Biology Course Unit 1
Leaf cut through
Cut end magnified
Section highlymagnified
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
Cuticle
Upper Epidermis
Palisade Mesophyll
Spongy Mesophyll
Lower Epidermis
StomataGuard Cells Stoma Pore
Xylem / Phloem
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National 4/5 Biology Course Unit 1CO2
H2O
Glucose O2
Light
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National 4/5 Biology Course Unit 1
Stomata are made up of special cells which control the size of a smallpore
A) Guard cells – these change shape and control the size of :
B) Pore
Stomata also control theexchange of gases by the leaf
Stomata are found on the bottom surface
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National 4/5 Biology Course Unit 1
The guard cells take in water by osmosis.
They swell more outwards than inwards due to the size of cell wall.
This pushes back epidermal cells and opens the pore.
They close by losing water.
Guard Cells
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National 4/5 Biology Course Unit 1
Part of Leaf Function
Waxy Cuticle Waterproof layer prevents water evaporation
Epidermis These cells on top and bottom of leaf are for protection
Palisade Mesophyll These cells under the upper epidermis is where photosynthesis occurs
Spongy Mesophyll Photosynthesis occur in the cells and O2 and CO2 can diffuse through the air spaces
Stomata These cells are in the lower epidermis and let gases
and water in and out.
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National 4/5 Biology Course Unit 1
Three possible factors can limit the rate of photosynthesis in a plant when they are in short supply :-
• Light intensity – this limits the energy available.• Carbon dioxide concentration – this is an essential raw material
• Temperature – this limits the rate at which the enzymes controlling photosynthesis work.
Limiting factors
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National 4/5 Biology Course Unit 1
Effect of light on the rate of photosynthesis
We can use the rate of production of oxygen bubbles by pond weed to measure the rate of photosynthesis
Diagram “bubbler”
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
• A large water trough or sheet of glass stops the heat from the lamp from affecting the experiment.
• Lamp moved away -> less oxygen bubbles produced
• The amount of light therefore limits the rate of photosynthesis. It is called a limiting factor.
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National 4/5 Biology Course Unit 1
Incr
easi
ng r
ate
of
phot
osyn
thes
is
Increasing light intensity
Part AAs light intensity increases the rate of photosynthesis increases.
Part BFurther increases in light causes no further increase in the rate of photosynthesis since the rate is limited by a shortage of some other factor e.g. carbon dioxide or temperature
Point X Optimum
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National 4/5 Biology Course Unit 1
Incr
easi
ng r
ate
of
phot
osyn
thes
is
Carbon Dioxide Concentration
Part AAs CO2 conc. increases the rate of photosynthesis increases.
Part BFurther increases in CO2 conc. causes no further increase in the rate of photosynthesis since the rate is limited by a shortage of some other factor e.g. light or temperature
Point X Optimum
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National 4/5 Biology Course Unit 1
Incr
easi
ng r
ate
of
phot
osyn
thes
is
Increasing light intensity
0.2% CO2
0.3% CO2
0.4% CO2
light intensity is limiting factor
CO2 is limiting factor
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National 4/5 Biology Course Unit 1
Incr
easi
ng r
ate
of
phot
osyn
thes
is
Increasing temperature
Part AAs temperature increases the rate of photosynthesis increases.
Part BFurther increases in temperature results in a drop in the rate due to the denaturing of the enzymes that carry out photosynthesis
Point X Optimum
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National 4/5 Biology Course Unit 1
Photosynthesis and horticulture
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
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National 4/5 Biology Course Unit 1
Photosynthesis and horticulture
Horticulture is the cultivation of plants in gardens and greenhouses.
The use of a greenhouse helps remove limiting factors:
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National 4/5 Biology Course Unit 1
(a) Lighting and heat
By increasing the light, the rate of photosynthesis increases and leads to an increase in the growth rate of the crop:
• crop is ready to be picked earlier.• increased crop yield.
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National 4/5 Biology Course Unit 1
(b) Carbon dioxide enrichment
Increased carbon dioxide in the atmosphere increases the yield (size) of crops. This happens because the rate of photosynthesis is increased.