LO: To describe the appearance and function of the main organelles found
within cells
Starter
Complete worksheet ‘Well - what do you know?’
BATS
•Describe outline of course and expectations of teachers
•Name organelles in eukaryotic and prokaryotic cells
• Identify similarities and differences between eukaryotic and prokaryotic cells
•Describe the functions of the organelles in eukaryotic and prokaryotic cells
1. Holiday pack - collect in
2. Handbook - go through key points
3. Expectations
4. Independent study
5. Revision Guides
6. Science Blog - Mrs Skuse’s AS Keynotes 2012-13
Introduction to course
You will discover that things are a lot more complicated and
detailed than you thought at GCSE
THIS becomes THIS!
You Tube clips to watch
http://www.youtube.com/watch?v=wJyUtbn0O5Y - the inner life of a cell ( 3 mins)
http://www.youtube.com/watch?v=ky8Xs3JhRc0 - Exploring the living cell - (3 mins)
http://www.youtube.com/watch?v=Ao9cVhwPg84&feature=related - voyage inside the cell (15 mins)
http://www.youtube.com/watch?v=1Z9pqST72is - good lecture about the cell (14 mins)
There are 2 main types of cells - (NOT animal and plant as you learnt at GCSE)
Prokaryotic - these are the oldest types of cells and mainly consist of bacteria -
they do NOT have any membrane-bound
organellesEukaryotic - these evolved more recently and
consist of all plant and animal cells - they contain
membrane bound organelles
Prokaryotic and Eukaryotic
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The bacteriumBacterial
chromosome
Plasmids
Ribosomes
Cell wall
Cell membranes
Cytoplasm
Today we are going to focus on
Eukaryotic cells
Cells are very small and we need microscopes to study themTo see the structures
within a cell we need to use a special kind of microscope called
and ‘electron microscope’ - we will learn more about this
next weekThe detail within a cell is called its
‘ultrastructure’
Structure of an epithelial cell
An epithelial cell is a
eukaryotic cell
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands.
Put the following in order of size starting with the smallest
organ, cell, atom, system, organism, organelle, tissue
An organelle is a specialised subunit within a cell that has a specific function, and is usually separately enclosed within
its own lipid bilayer.
You have been given 2 diagrams of eukaryotic cells
They contain organelles that are visible with an electron microscope.
Using textbooks
label as many as you can
What do cells have organelles? A cell does a huge number of complex things. It is basically a factory. Why does your house need rooms?
The cell does different things in different organelles. It is very similar to your body doing different things with different organs (e.g. your lungs breathe). In a cell mitochondria produce energy, ribosomes make protein. ...
Organelles make cells more efficient
All the molecules, enzymes etc
needed for each purpose can be
found close together in each
organellee.g. all the reactants and
enzymes needed for photosynthesis can be found in a
chloroplast
You need to know the function of the main organelles
Worksheet Cell Ultrastructure
http://www.uni-mainz.de/FB/Medizin/Anatomie/workshop/EM/EMZelleE.html
Electron micrographs
http://www.youtube.com/watch?v=o1GQyciJaTA&feature=related - 6 min clip
Write down everything you know about the nucleus
The nucleus
- Contains the cells hereditary material
- Controls the cells activities 10-20 micrometers
Nucleus - main parts
1. Nuclear envelope - double membrane. It’s outer membrane
is continuous with the endoplasmic reticulum and often
has ribosomes on its surface.
It controls the entry and exit of materials and contains the
reactions happening within it.
2. Nuclear pores - allows the passage of large molecules e.g. mRNA. About 3000 pores in each nucleus - each 40-100nm in diameter.
Nucleus - main parts3. Nucleoplasm - the
granular, jelly-like material that makes up bulk of the
nucleus4. Chromatin - the DNA
found within the nucleoplasm - it makes up chromosomes. When the
cell is not dividing chromosomes are not
tightly coiled but are in a relaxed looser form known
as chromatin5. Nucleolus - manufactures ribosomal RNA and assembles the ribosomes
Nucleus - FUNCTIONS1. Control centre -
of the cell . It produces mRNA and
hence protein.2. Retains the
genetic material - in the form of DNA or
chromosomes
3. Manufactures ribosomal RNA and
ribosomes
The mitochondrion
1. Rod shaped 1-10 micrometers in
length 2. Double
membrane - the outer one controls entry and exit of
material.
The inner membrane is folded to form
cristae.
The mitochondrion3.Cristae -
extensions of inner membrane. They provide a large surface area for attachment of
enzymes involved in respiration3. Matrix - rest of mitochondria. semi-rigid
material containing protein, lipids and traces of DNA which allows the mitochondria to control production of their own proteins.
Enzymes involved in respiration are found in the matrix.
The mitochondrion - functionSome stages of RESPIRATION happen in the mitochondria.
They produce the energy-carrier molecule ATP
Q. - why do muscle cells and epithelial cells have more mitochondria than say a skin cell?
The Endoplasmic reticulum (ER)Elaborate, 3-
dimensional system of sheet-like membranes
that spread throughout the cytoplasm - it is
continuous with the outer nuclear membrane.The membranes
enclose flattened sacs called cisternae
2 types of ER
Rough Endoplasmic reticulum (RER)
Has ribosomes on the outer surfaces
of membranes.
Functions
1. To provide a large surface area for the synthesis of proteins and glycoproteins
2. To provide a pathway for the transport of materials, especially proteins throughout the cell.
Smooth Endoplasmic reticulum (SER)
Lacks ribosomes on its surface and is
often tubular.
Functions
1. To synthesise, store and transport lipids
2. To synthesise, store and transport carbohydrates
Golgi Apparatus
Similar to SER but more compact.
It consists of a stack of membranes that make up
flattened sacs or cisternae, with small
rounded hollow structures called vesicles.
The proteins and lipids produced by the ER are
passed through the Golgi apparatus in strict
sequence.
Golgi Apparatus
The Golgi modifies the proteins
It adds non-protein components e.g.
carbohydrate to them.
It also labels them which allows them to be
accurately sorted and sent to their correct
destinations
Golgi Apparatus
Once sorted the modified proteins and lipids are
transported in vesicles which are pinched off
from the ends of the Golgi cisternae.These vesicles move to
the cell surface where they fuse with the
membrane and release their
contents to the outside
Golgi Apparatus - FUNCTIONS1. Add carbohydrate to
proteins to form glycoproteins
2. Produce secretory enzymes
3. Secrete carbohydrates, such as those used in making
cell walls in plants
4. Transport, modify and store lipids
5. Form lysosomesQ. What kinds of cells will have very well-developed Golgi apparatus?
LysosomesThese are formed when the vesicles produced by the Golgi apparatus contain enzymes such
as proteases and lipases.
Q. Why are these enzymes isolated in lysosomes?
Up to 50 different enzymes in each
lysosomeUp to 1.0 micrometers
in diameter
Lysosomes - FUNCTIONS1. Break down material ingested by phagocytic cells,
such as white blood cells
2. Release enzymes to the outside of the cell
(exocytosis) in order to destroy material around the
cell
3. Digest worn out organelles so that the useful chemicals they are made of can be re-
used
Completely break down cells after they have died
(autolysis)
Q. Name 2 types of cells you might
find a lot of lysosomes in
RibosomesSmall granules found in all
cells either in the cytoplasm or associated
with the RER.
2 Types80S type - found in
eukaryotic cells - 25 nm in diameter
70S type - found in prokaryotic cells -
slightly smaller
Ribosomes - 2 subunits
Each subunit contains ribosomal RNA and
proteinThey occur in vast
numbers - make up to 25% of the dry mass of a
cell.
VERY important in protein
synthesis
Microvilli
Finger-like projections of the epithelial cell.
What do you think their main purpose
is?
To increase the surface area to
allow more efficient absorption
Now do the following
Answer Summary questions on Page 49 of
text book
References Glenn Toole, Susan Toole (2008). A2 Biology. Cheltenham: Nelson
You Tube clips to watch
http://www.youtube.com/watch?v=wJyUtbn0O5Y - the inner life of a cell ( 3 mins)
http://www.youtube.com/watch?v=ky8Xs3JhRc0 - Exploring the living cell - (3 mins)
http://www.youtube.com/watch?v=Ao9cVhwPg84&feature=related - voyage inside the cell (15 mins)
http://www.youtube.com/watch?v=1Z9pqST72is - good lecture about the cell (14 mins)
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