721211
Module 1: Cells
- Microscopes
- light microscope
- resolution of 200nm (low
resolution means means
structures closer together
than 200nm will appear as
one object)
- Maximum
magnification
of 1,500x
- resolution of 200nm (low
resolution means means
structures closer together
than 200nm will appear as
one object)
- Electron
micropscope
- Transmisson Electron Microscope: 2D
image produced, max. magnification is
500,000x. Electron beam passes through a
very thin prepared sample, electrons pass
through denser parts less easily, giving contrast.
- Scanning Electron Microscope:
Electron beam directed on the sample,
electrons don't pass through specimen,
hey are bounced off. Final image is 3D.
Max. magnification is 100,000x
- Advantages: Higher resolution, means they can be used to
produce more detailed images of structes of organelles. SEM
produces 3D image revealing contours and cellular arrangement
- not possible with a light microscope.
- Limitations: Electrons deflected by
molecules in air, so needs to be in vacuum.
V. expensive and need specialist training
and equipment.
- Transmisson Electron Microscope: 2D
image produced, max. magnification is
500,000x. Electron beam passes through a
very thin prepared sample, electrons pass
through denser parts less easily, giving contrast.
- Staining
- Biological material not
coloured. hard to
distinguish features.
- Coloured stains are used to stain specimens,
chemicals bind to other chemicals on the specimen
allowing it to be seen.
- Biological material not
coloured. hard to
distinguish features.
- Sectioning
- Specimens are embedded in
wax. Thin sections cut without
distorting the structure
- V. useful for
soft tissue
- Specimens are embedded in
wax. Thin sections cut without
distorting the structure
- Magnification: is the degree
to which the size of an image
is larger than the object itself.
- mag =
image size /
actual size
- mag =
image size /
actual size
- Resolution: is the degree to wihch it is
possible to distinguish two objects that
are very close together
- light microscope
- Organelles
- NUCLEUS
- Houses all the genetic information in
the form of DNA, contains instructions
for for making proteins.
- Largest organelle, when stained
contains darker parts of chromatin.
- Houses all the genetic information in
the form of DNA, contains instructions
for for making proteins.
- NUCLEOLUS
- Makes ribosomes and RNA which pass through
the nuclear pores into the cytoplasm and are used
in protein synthesis.
- Makes ribosomes and RNA which pass through
the nuclear pores into the cytoplasm and are used
in protein synthesis.
- NUCLEAR ENVELOPE
- Double membrane with nuclear pores to
allow mRNA to go out to the ribosomes
for use in protein synthesis.
- Double membrane with nuclear pores to
allow mRNA to go out to the ribosomes
for use in protein synthesis.
- ENDOPLASMIC RETICULUM
- Series of flattened membrane bound
sacs called cisternae. Rough ER studded
with ribosomes and smooth is not.
- Rough ER transports proteins
that were made by attached
ribosomes. Smooth ER is
involved with making lipids.
- Series of flattened membrane bound
sacs called cisternae. Rough ER studded
with ribosomes and smooth is not.
- GOLGI APPARATUS
- A stack of
membrane-bound
flattened sacs
- Receives proteins from the ER and
modifies and packages them into
vesicles that can be transported.
- A stack of
membrane-bound
flattened sacs
- MITOCHONDRIA
- Inner membrane is highly folded to form
the cristae, the central part of the
mitochondrion is called the matrix.
- Site of respiration, where ATP is produced.
Almost of activites in the cell are driven by the
energy released from ATP.
- Inner membrane is highly folded to form
the cristae, the central part of the
mitochondrion is called the matrix.
- CHLOROPLASTS
- Only found in plant cells. Have network of
flattened membrane sacs called thylakoids, a
stack of these are called a granum. Contain
chlorophyll in thylakoids membranes.
- Site of photosynthesis in plant cells. Light energy is used to drive the
reactions of photosynthesis are carbohydrates are made from water
and carbon dioxide.
- Only found in plant cells. Have network of
flattened membrane sacs called thylakoids, a
stack of these are called a granum. Contain
chlorophyll in thylakoids membranes.
- LYSOSOMES
- Contain lysins which are powerful
digestive enzymes which break down
organelles, pathogens and cells.
- Specialised lysosome is acrosome found
the hea dof a sperm cell helps penetrate
the egg by breaking down materials.
- Contain lysins which are powerful
digestive enzymes which break down
organelles, pathogens and cells.
- RIBOSOMES
- Ting
organelles
- Site of protein synthesis in
the cell, code mRNA from the
nucleus and assemble
proteins from amino acids.
- Ting
organelles
- CELL SURFACE MEMBRANE
- Controls the entry and exits of
substance into and out of the
cell
- Controls the entry and exits of
substance into and out of the
cell
- FLAGELLA (UNDULIPODIA)
- Found in eukaryotes.
Hair like extensions
that stick out the
surface of the cells,
Move by using ATP.
- Found in eukaryotes.
Hair like extensions
that stick out the
surface of the cells,
Move by using ATP.
- CYTOSKELETON
- Network of protein
fibres the keep the
cells shape
porviding an internal
framework.
- Also determine the
cells shape. Moves
organelles such as
mitochondira, RNA,
chromosomes. Move
vesicles along the
microtubule network,
hold organelles in
places
- MIRCOTUBULES
- Cyclinders 25nm in diameter,
made of tubulin. They
themsevles do no tmove, but
they provide an anchor for
protein to move along, move
organelles along the fibres.
eg. chhromosomes are
moved during mitosis, how
vesicles move from the ER to
the golgi. They use atp to
drive these movements.
- Cyclinders 25nm in diameter,
made of tubulin. They
themsevles do no tmove, but
they provide an anchor for
protein to move along, move
organelles along the fibres.
eg. chhromosomes are
moved during mitosis, how
vesicles move from the ER to
the golgi. They use atp to
drive these movements.
- Network of protein
fibres the keep the
cells shape
porviding an internal
framework.
- NUCLEUS
- Protein Synthesis
- 1. The gene containing the instructions for the
porduction of the hormone is copied onto a
piece of mRNA.
- 2. mRNA leaves the nucleus
through the nuclear pore.
- 3. mRNA attaches
to a ribosome.
- 4. Ribosome
reads the
instructions to
assemble the
protein.
- 5. Molecules are
pinched off in
vesicles and travel
towards the golgi
appartus.
- 6. Vesicle fuses with the
Golgi apparatus.
- 7. Golgi apparatus
processes and
packages the
molecules ready for
release.
- 8. The molecules are pinched
off in vesicles from the golgi
and move towards the cell
surface membrane.
- 9. Vesicles fuses with
the cell surface
membrane.
- 10. Cell surface membrane
opens to release molecules
outside this is exocytosis.
- 1. The gene containing the instructions for the
porduction of the hormone is copied onto a
piece of mRNA.
- Propkaryotes
and Eukaryotes
- Prokaryotes do not have a
nucleus, they are bacteria and are
much smaller than Eukaryotes.
- Prokaryotes have
no mitochondria,
instead they have
mesosomes.
- They have smaller
ribosomes; prokaryotes have
70s and eurkaryotes have
80s.
- Prokaryotes do
not have a
vacuole.
- Prokaryotes' cell walls are made of
peptidoglycan, whereas eurkaryotes cell
walls are present in plant calls and are
made of cellulose.
- Prokaryotes do not have a
nucleus, they are bacteria and are
much smaller than Eukaryotes.
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