UNIT OF LIFE

CELLhttp://www.aimediaserver.com/studiodaily/harvard/harvard.swf

Angstrom, A metric unit of length equal to one ten billionth of a meter .

DISCOVERY OF THE CELL History of the cellular studies relies on the development

of technology especially development of microscope. In 1590 Dutch spectacle makers Zaccharias and Hans

Janssen and developed a complex magnifier by using several lenses. This was the first microscope.

1632 – 1723: Antonie van Leeuwenhoek teaches himself to grind lenses, builds a microscope and draws protozoa, from rain water, and bacteria from his own mouth.

1665: Robert Hooke discovers cells in cork and named them as cells. Then observed cells in living plant tissue using an early microscope

1831: Robert Brown observed nucleus and named it. Theodor Schwann (1839) and Matthias Jakob Schleiden

(1838) elucidate the principle that plants and animals are made of cells, concluding that cells are a common unit of structure and development, and thus founding the cell theory.

1839: Johannes Purkinge named the jelly like material in the cell as protoplasm(today cytoplasm)

1853: Rudolph Virchow stated that cells always emerge from preexisting cells.

The first electron microscope prototype was built in 1931 by the German engineers Ernst Ruska and Max Knoll. In electron microscopes electron reflections are used to determine the structures.

1953: Watson and Crick made their first announcement on the double-helix structure for DNA. X rays helped them.

1981: Lynn Margulis published Symbiosis in Cell Evolution detailing the endosymbiotic theory.

CELL THEORY All organisms are made up of cells Cells are the structural functional unit of all

organisms. All cells have cellular activities. New cells arise from old cells.

Cell needs to survive and reproduce

To survive, organisms need to get energy

They have to produce new molecules

They have to destroy harmful materials

They store unnecessary molecules

They package and transport molecules

They are protected by membrane

They should be supported

Nucleus

mitochondria

Ribosome, chloroplast, Endoplasmic reticulum

Lysosome

Vacuole

Golgi body

Cell membrane

Cell skeleton

Jelly like fluid filling the cell. It has water, protein, lipid, carbohydrates, minerals and enzymes. Most of the cellular reactions occur in the cytoplasm. Some enzymes produce ATP during breakdown of glucose in cytoplasm and they also use ATP for this reaction.(glycolysis)

CYTOPLASM

CELL MEMBRANESurrounds the cell . It has 2 layers of lipid and some protein molecules within the lipid molecules. Cell membrane is selective permeable (semipermeable).

The structure is named as fluid mosaic model. Lipid gives the fluidity and flexity. Proteins have recognition and transport role. In the membrane there are carbohydrates which recognize foreign particles.

CELL MEMBRANE

Ribosomes They don’t have membrane. They

are very small organelles. Play important role in protein synthesis. Some are free in the cytoplasm but some are on the nuclear envelope and endoplasmic reticulum.

They are made up of proteins and rRNA

Polysome-many ribosome

Rough Endoplasmic Reticulum

They have membrane. They are tubular networks with ribosomes on them. They play role in protein synthesis and protein transport.

Smooth Endoplasmic Reticulum They have membrane. They

are tubular networks but they don’t have ribosomes. They play role in lipid synthesis.

Golgi Body They have membrane. They

are flattened sacs and have important role in package of synthesized molecules. They work with endoplasmic reticulum. Transport or export synthesized molecules out of the cell. Modify molecules by adding groups(glucose, phosphate, sulphate)

Help formation of cell wall in plants.

Help formation of lysosomes

Lysosome They have membrane. They

contain hydrolytic enzymes. They are formed by Rough ER and golgi. They digest foreign or unnecessary molecules.

Only in animal cells (except red blood cells)

When they fuse with foreign molecule they form secondary lysosome.

Peroxisomes

Membrane enclosed organelles. Contain catalase enzyme which breaks up H2O2 and form H2O and O2

Vacuoles They are fluid filled organelles. They are surrounded by

membrane. They store some food and wastes. They are very big in old plant cells. In animal cells they are very small.

Food vacuole, : digests food in one celled or primitive organisms like amoeba

Contractile vacuole: throws out excess water like paramecium

Centrosome(have 2 centrioles)

2 centrioles form a centrosome. It is important in cell division.Made up of proteins. It is only found in animal cells.Can form cilia and flagella.

Mitochondria

They are double membraned organelles. They produce energy by breaking down the food and by using oxygen. This process is called cellular respiration.

C6H12O6+6O2 6CO2+6H2O+ATP

Plastids are only found in plant cells.(Chloroplast (contain chlorophyll–green as spinachChromoplasts-(contain xanthophyll, carotene- red, orange, yellow in carrot,tomatoes Leucoplasts- colorless in potato(turn to green in sunlight))

Chloroplasts ar large organelles found only in plant cells. They have double membrane.

Chloroplasts make photosynthesis. They use light energy to convert inorganic (CO2, H2O) molecules into organic(glucose) molecule.

66CCOO22+12+12HH22OO CC66HH1212OO66+6+6HH22OO+6+6OO22

They produce ATP but use it in dehydration

synthesis.

Comparison of mitochondria and chloroplast

Mitochondria Chloroplasts

Produce ATP(not uses it)

Produce and uses ATP inside.

Have DNA, RNA and ribosomes

Have DNA, RNA and ribosomes

Have ETS on cristae Have ETS on grana

Use Oxygen, produce carbondioxide

Use carbondioxide, produce oxygen

Catabolism Anabolism

Double membrane Double membrane

Endosymbiosis

Nucleus

It is the brain of the cell. It is surrounded by nuclear envelope(double membrane). It contains the genetic material (DNA) of the organism.

Nuclear membrane(envelope)

It covers the nucleus. It is double membraned It has some pores to allow RNA exchange.

Nucleolus

Some part of the genetic material, which is specific for rRNA production is condensed and form nucleolus. So it is important for ribosome formation.

PROKARYOTE AND EUKARYOTE CELLSProkaryote Eukaryote

Nucleus (nuclear membrane)

Absent; A single circular chromosome

Present; Multiple chromosomes

Membrane-enclosed organelles

Absent Present (mitochondria, chloroplasts, endoplasmic reticulum, Golgi, lysosome, etc.)

Cell wall Present;protein+carbohydrate

Absent in animal; if present (plants & fungi) cellulose

Cell division Binary fission Mitosis

Ribosome Smaller Larger

Plant and animal cellsStructure Animal cell Plant cell Feature and function

Cell wall Absent Present(cellulose) Support and protection

Cell membrane Present Present Regulation of cellular transport

Cytoplasm Present Present Jelly like fluid

Nucleus Present Present Controls cell activities

Nucleolus Present Present Ribosome production

Mitochondria Present Present Energy production

Endoplasmic reticulum

Present Present Protein and lipid synthesis

Golgi Present Present Package of molecules

Ribosome Present Present Protein synthesis

Lysosome Present Absent Storage of digestive enzymes

Vacuole Present (small) Present (big) Storage of unnecessary materials

Centriole Present Absent İmportant in cell division

Plastids Absent Present Food production and storage

ChromosomesThe threadlike material is called chromatin. It condenses during cell division and form chromosomes.

Each chromosome contains DNA and protein.

Chromosomes carry genes which code for the characters.

Humans have 46 chromosomes.

23 pairs of chromosomes.

23 of them come from father and 23 of them come from mother.

Each pair codes for same trait (characteristic).They are called homologous chromosomes.

Sister chromatids

DNA DNA with proteins chromatin structure DNA replication Chromosome

The threadlike material is called chromatin. It condenses during cell division and form chromosomes.

Sister chromatids are the 2 chromatins after then DNA replication. Same with each other.

Cell life cycle

Cells should produce new cells by dividing. But during reproduction or formation of new cells, The genetic material should be kept untouched.

Cells undergo 2 types of division. Mitosis and meiosis. Mitosis is the process of making new body cells. Meiosis is the type of cell division that creates egg

and sperm cells(gametes).

Cell life cycle and Mitosis

In the life cycle of a cell:1. Cell grows (G1)2. Decide to divide and

replicate DNA (S)3. Prepare for division(G2)4. DivideThis cycle occurs in every

cell but not in nerve and muscle cells. They stay at G1 phase, never divide.

The series of events from one cell division to the next is called cell cycle.

MitosisMitosis is important in: Repair and regeneration. Growth Mitosis is a fundamental process for life. During

mitosis, a cell duplicates all of its contents, including its chromosomes, and splits to form two identical daughter cells.

As a result of the mitosis: 2 new cells are formed New cells have same genetic material and

chromosome number with mother cell. The genetic material and chromosome number of the

new cells are same.

Mitosishttp://www.whfreeman.com/thelifewire6e/content/ch09/ani0901mov1.html

http://www.sumanasinc.com/webcontent/anisamples/biology/biology.html

Interphase: Resting period of the cell. Cell carries out normal activities. In S phase DNA of the cell replicates itself. 2 sister chromatids are formed.

Prophase: nuclear membrane disappears. Centrioles go to the opposite poles.

Metaphase: Chromosomes with sister chromatids stay in the middle of the cell (equator). Spindle fibers are formed.

Anaphase: Sister chromatids separate from each other and go to the opposite poles with the help of the spindle fibers.

Telophase: Chromatids reach to the poles and nuclear membrane is formed . Spindle fibers disappear.

1. A cell with 4 chromosomes undergoes 1 mitotic division.a. How many cells will form? b.How many chromosomes does each cell contain?

2. A cell with 4 chromosomes undergoes 3 mitotic division.a. How many cells will form at the end? b.How many chromosomes does each cell contain?

3. At the end of the successive mitotic divisions 256 cells are formed. How many mitotic divisions occured?

2 cells with 4 chromosomes

23 = 2 x 2 x 2 = 8 cells with 4 chromosomes

2x2x2x2x2x2x2x2= 256 28 = 256 8 divisions

Meiosishttp://www.sumanasinc.com/webcontent/anisamples/majorsbiology/meiosis.html

Meiosis is important in: formation of gametes (sperm, egg) reducing chromosome number genetic variation

As a result of the meiosis: 4 new cells are formed New cells can have different genetic makeup from the

mother cell New cells have half of the chromosome number of the

mother cell.(n) The genetic makeup of the new cells can be different

from each other.

Meiosishttp://www.whfreeman.com/thelifewire6e/con_index.htm?09

Interphase: DNA replicates itself

Prophase I: 2 Homologous chromosomes

(tetrad) exchange genes (crossing over)

Metaphase I: Homologous chromosomes (tetrad) line up in the middle of the cell(equator). Spindle fibers attach to the chromosomes.Anaphase I: Homologous chromosomes separate from eachother and go to the opposite poles. Telophase I: Chromosomes reach to the opposite poles. Two cells are formed . The chromosome number is reduced by meiosis I.

Prophase II: The chromosomes become shorter and thicker. Metaphase II: Spindle fibers attach to the chromatids of the chromosomes. Anaphase II: Sister chromatids of the chromosomes are separated and go to the opposite poles of the cells. Telophase II: Totally 4 cells are formed. Each cell can have a different genetic make up and half of chromosome number

What should we know about meiosis I?

Crossing over(gene exchange)between homologous chromosomes occurs in Meiosis I (Prophase). Genetic variation occurs .

Homologous chromosomes are separated from each other in meiosis I, chromosome number is reduced by half in Meiosis I.

Homologous chromosomes line randomly in Metaphase I. Causes variation.

What should we know about meiosis II?

Sister chromatids are separated from each other in Meiosis II. (similar to mitosis)

Mitosis and meiosisMITOSIS MEIOSIS

1. takes place in body cells. 1. takes place in germ cells and forms sex cells.

2. No crossing over (gene Exchange) 2. crossing over can happen between homologous chromosomes.(Tetrad forms)

3. It has 1 cycle of the phases (1 division) 3. It has 2 cycle of phases (2 division)

4. Produces 2 cells 4. Produces 4 cells

5. newly formed cells have the same chromosome number of the parent cell(2n)

5. Newly formed cells have the half of the chromosome number of the parent cell (n)

6. The genetic make up of the newly formed cells are same with each other and with the parent cell

6. The genetic make up of the newly formed cells can be different from each other and from the parent cell

7. Only sister chromatids separarte. 7. Homologous chromosomes separate at the 1st division, sister chromatids separarte in the 2nd division.

If there is no crossing over at the end of 1 st part of meiosis

n=1

Homologous chromosomes separated and went to opposite 2 cells (chr number is halved)

At the end of the 2nd part of the meiosis

n=1

Sister chromatids are separated and went to the opposite to cells

A

B

A

b

If this cell undergoes meiosis, draw the genetic makeup uf the new cells? 2n= 2

If there is crossing over, between A-B and A-b

crossing over doesn’t change the gene combination

n=1

A

B

A

b

A

B

A

B

A

b

A

b

A

b

A

B

A

b

A

b

A

B

A

B

Sister chromatids are separated and went to the opposite to cells

If this cell undergoes meiosis, draw the genetic makeup uf the new cells? 2n= 2

A

B

a

b

If there is crossing over at the end of 1 st part of meiosis

n=1

New genetic makeup is formed as a result of crossing over

At the end of the 2nd part of the meiosis

n=1

Sister chromatids are separated and went to the opposite to cells

If there is no crossing over at the end of 1 st part of meiosis

n=1

Homologous chromosomes separated and went to opposite 2 cells (chr number is halved)

At the end of the 2nd part of the meiosis

n=1

Sister chromatids are separated and went to the opposite to cells

A

B

a

b

a

b

a

bA

B

A

B

A

b

a

B

A

b

a

B

a

BA

b

A B

C

D

Changes in chromosome number, DNA amount and volume of cell

A cell undergoes some cell divisions and fertilization. Can you find them by looking at the graphic?

A B

C

D

Mitosis

Meiosis

fertilization

A gamete cell of an organism has 14 chromosomes? What is the chromosome number in stomach cells?

N= 14 2n= 28

What are the reasons of genetic variation in meiosis? Crossing over(gene exchange)between homologous

chromosomes occurs in Meiosis I (Prophase). Genetic variation occurs

Homologous chromosomes line randomly in Metaphase I. Causes variation.

Mutations during meiosis also cause variation.

If an animal has 7+Y chromosome in one sperm cell, What will be the number of autosomes and gonosomes in kidney cells?

14 + XY

Nondisjunction

Normal meiosisFailure of separation of

homologous chromosomes or separartion of sister chromatids

Transport across membrane

Cell membrane is semipermeable. Some small molecules can pass the cell membrane easily but some molecules can not pass. Cell should take needed materials from the outside of the cell and send some secretions out of the cell.

According to the properties of the materials, cells use different ways to take in or give out molecules.

Transport mechanismsMechanisms that don’t need energy

Mechanisms that need energy

1. Passive Diffusion

2. Facilitated Diffusion

3. Osmosis

1. Active transport

2. Endocytosis

3. Exocytosis

1. PASSIVE DIFFUSION Diffusion is the movement of molecules from a

region of high concentration to low concentration. When you put a drop of ink into the water , ink

molecules diffuse within the water. When you open a parfume bottle, the smell diffuses. Small molecules

move in that way.

Oxygen,

Carbondioxide, urea

Important!Concentration gradient, temperature, size of

the molecules effect the diffusion rate.

2. Facilitated diffusion It is the movement of molecules from high

concentration to low concentration through the membrane with the help of a protein.

Ex. Glucose, fructose, galactose

3. OSMOSIS

Experiment of cellular transport1• Peel the potatoes• Cut it half and make a

hollow in the centre. (Don’t damage the potato)

• Put 2 halves in to the water.

• Dry the hollows and put one tablespoon of sugar inside one of the potatoes.

2• Peel the potatoes• Cut same size of

rectangular sticks from potato.

• Note the sizes of the sticks(measure the length.

• Label the petridishes as the concentration, then put 1 potato piece to each petri. Put the sugar solutions to each petri.

• Wait for 10 min. Then note the size of the sticks(measure the length..

3• Tie one side of the

tubing• Pour starch solution

into the tubing• Tie the other side• Put the sausage with

starch into the lugol solution

Sausage tubing with starch

Lugol(iodine) solution

Sugar gets wet because of osmosis. Water enters the inner part of the potato

Potato stick in distilled water will take in water.

But other sticks will lose water

Lugol enters the sausage tubing and starch becomes black. But starch can’t pass the membrane.

a HYPOTONIC (= hypoosmotic) solution is one which has relatively more water molecules (and fewer solutes) than a HYPERTONIC (= hyperosmotic) solution.

ISOTONIC (isoosmotic) solutions have equal concentrations of solutes.

Important!

Osmotic pressure is important for the movement of water.

Osmotic pressure is the ability to take water.

If it is high in one area , that area can take in water.This means that the solute concentration of that area is high.

Osmotic pressure is high=solute concentration is high= water concentration is low= ability to take water is high

Plasmolysis:Plasmolysis is the loss of water from the cell by osmosis. If the concentration of the cell is lower than the outside(solute is low, water is high), water moves out of the cell. Cell shrinks.

Deplasmolysis: is the gain of water from the outside by osmosis. If the cell has higher concentration than the outside, water moves in and plasmolyzed cell swells.

Turgor: is the force(pressure) exerted to the cell wall of the cell.

1. Which of the organelles can increase the osmotic pressure of the cell?

a. Lysosome b. centrosome c. ribosome

d. nucleus e. mitochondria

2. Compare the osmotic pressures of the following cells?

A B

1. ACTIVE TRANSPORT

In diffusion and osmosis, no energy is used. But in some cases to transport molecules across membranes, we use energy . This process is called active transport.

Active transport is the movement of molecules from low concentration to hıgh concentration.

1. ACTIVE TRANSPORT During active transport molecules are carried

from low concentration to high concentration. ATTENTION!!! (in diffusion molecules flow from high concentration to low concentration BUT in active transport they are carried from low concentration to high concentration)

This transport is very hard so cell spends ATP(energy) .

Active transport carries small molecules that are hard to pass.

Example. Na + / K+ pump

Na ions are very low in concentration in part A (outside of the cell).

And Na ions are high in concentration in part B (inside the cell)

If cell wants to take more Na, then it has to take more Na only by ACTIVE TRANSPORT.

A

low

Bhigh

The movement of Na and K molecules across membrane from low concentration to high concentration.

2. Endocytosis

Exocytosis is a way for cell to throw out big particles, cell membrane gets larger.

It is the opposite of endocytosis. Cell spends ATP.

Endocytosis is a way for cell to take in large particles by engulfing . Cell spends ATP. Cell membrane gets smaller by engulfing.

Phagocytosis is the intake of solid particles.(not in plants) Pinocytosis is the intake of liquid molecules.

3. Exocytosis

Question

Pressure OP A F

TP t1 time

OP= Osmotic pressure

AF= absorption force

TP= Turgor pressure

I. It will take in water as long as osmotic pressure is larger than turgor pressure.

II. At t1 cell is in the turgor stage.

III. As the osmotic pressure decreases, force of absorption increases

Which one is true?

Metabolism

needs energy(ATP)

METABOLISM

All chemical activities within the cell are called metabolic activities or metabolism of the organism. There are two kinds of metabolic activities.

Anabolism or the anabolic reactions are synthesis reactions. They produce polymers. For example formation of proteins, polypeptides.Water is formed. Needs energy.

Catabolism or catabolic reactions are the breakdown reactions. They produce monomers. For example formation of amino acids from proteins, monosaccharides from carbohydrates. Water is used.

Multicellularity an early step in the evolution of multicellular organisms was the

association of unicellular organisms to form colonies. The simplest way of achieving this is for daughter cells to remain together after each cell division. In Volvox the individual cells forming a colony are connected by fine cytoplasmic bridges so that the beating of their flagella is coordinated to propel the entire colony along like a rolling ball. Within the Volvox colony there is some division of labor among cells, with a small number of cells being specialized for reproduction and serving as precursors of new colonies. The other cells are so dependent on one another that they cannot live in isolation, and the organism dies if the colony is disrupted

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Prophase

nuclear membrane disappears. If it is an animal cell, Centrioles go to the opposite poles. Don’t forget there is no centriole in plant cells.

Metaphase

Chromosomes with sister chromatids stay in the middle of the cell (equator). Spindle fibers are formed.

Anaphase Sister chromatids separate from each other

and go to the opposite poles with the help of the spindle fibers.

Telophase Chromatids reach to the poles and nuclear

membrane is formed . Spindle fibers disappear. Karyokinesis(division of nucleus) ends. Cytokinesis (division of cytoplasm) ends. If it is an animal cell cytokinesis is by burrowing.

If it is a plant cell cytokinesis is by formation of cell plate. Cell plate derives from golgi body.

Interphase Resting period of the cell. Cell carries out normal

activities. In S phase DNA of the cell replicates itself. 2 sister chromatids are formed.

Each organism has 2 pairs of chromosomes. One set comes from mother and other comes from father.Each pair codes for same trait (characteristic- eye color).They are called homologous chromosomes.But they can be different.