Transcript unit 1 – biology and disease

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
Introduction to course
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
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 and Eukaryotic
Prokaryotic - these are the
oldest types of cells and mainly
consist of bacteria - they do
NOT have any membranebound organelles
Eukaryotic - these evolved
more recently and consist of all
plant and animal cells - they
contain membrane bound
organelles
The bacterium
Bacterial
chromosome
Plasmids
Cytoplasm
Ribosomes
Cell wall
Copyright © Dean Madden, 2010
Cell
membranes
Today we are going to focus on
Eukaryotic cells
Cells are very small and we need
microscopes to study them
To 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 week
The 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
organelle
e.g. all the reactants
and enzymes
needed for
photosynthesis can
be found in a
chloroplast
http://www.youtube.com/watch?v=o1GQyciJaTA&feature=related - 6 min clip
You need to know the function of
the main organelles
Worksheet Cell
Ultrastructure
Electron micrographs
http://www.unimainz.de/FB/Medizin/Anatomie/workshop/EM/EM
ZelleE.html
The nucleus
Write down
everything you
know about 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 parts
3. Nucleoplasm - the granular,
jelly-like material that makes
up bulk of the nucleus
4. 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
chromatin
5. Nucleolus - manufactures ribosomal RNA and
assembles the ribosomes
Nucleus - FUNCTIONS
1. 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 mitochondrion
3.Cristae - extensions of
inner membrane. They
provide a large surface
area for attachment of
enzymes involved in
respiration
3. 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 - function
Some 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, 3dimensional 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 - FUNCTIONS
1. 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 lysosomes
Q. What kinds of cells will have very welldeveloped Golgi apparatus?
Lysosomes
These are formed when the
vesicles produced by the
Golgi apparatus contain
enzymes such as
proteases and lipases.
Up to 50 different
enzymes in each
lysosome
Up to 1.0 micrometers in
diameter
Q. Why are these enzymes isolated in
lysosomes?
Lysosomes - FUNCTIONS
1. 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
Ribosomes
Small granules found in all
cells either in the cytoplasm
or associated with the RER.
2 Types
80S 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 protein
They 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
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)
References
Glenn Toole, Susan Toole (2008). A2 Biology. Cheltenham: Nelson