This document includes the microscopes, the components of a cell, cell fractionation, transport and cholera

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  • Created by: AmaniF
  • Created on: 27-05-13 17:50
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How to view cells
Length of Image = Magnification x Length of specimen
Resolution = How detailed the image is
Magnification = How much bigger the image is than the specimen.
There are two electron microscopes which are a lot more detailed than the optical telescope; the
scanning and the transmission. The TEM's specimen needs to be stained and thin. It has a lower
resolution than the SEM. Both telescopes require a vacuum to work in. The SEM can create 3d
images; the TEM can see the structure on the inside of the specimen.
Transmission Electron Microscope
Denser parts of the specimen absorb more electrons, making them darker on the image.
TEM's give higher magnification images than the SEM
May only be used on thin specimens
Scanning Electron Microscope
Electrons are knocked off the specimen
This allows the surface to be shown in 3D
They give lower resolution and magnification than TEM's
Components of a cell
Folds on the surface of a cell, usually found in epithelial cells.
Help increase surface area for exchange surfaces.
An organelle surrounded by a nuclear envelope which contains many pores. This contains
chromatin and the nucleolus
Chromatin is made from proteins and DNA which control cell protein production. The pores
allow mRNA to pass to the ribosomes
Mitochondria are surrounded by a double membrane. The inner membrane is folded into
Cristae which gives it a large surface area. The space inside the inner membrane is called the
matrix which is involved in ATP production
These cells respire aerobically to make ATP molecules.
Small, membrane-bound vesicles.

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These contain digestive enzymes which are used to digest invading cells, worn out cell
components, or for self-programmed death.
Endoplasmic reticulum
This is an extensive network of cisternae held by the cytoskeleton
The smooth E.R. is involved in synthesising and processing lipids
The rough E.R. is studded with ribosomes. It folds and processes proteins that are made in
the ribosomes.
Golgi apparatus
A series of flattened membrane vesicles filled with fluid.
It transports proteins from the R.E.R. to the cell membrane to export.…read more

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To separate the organelles, you need to use a centrifuge. The test tube with the solution in is spun at
a low speed, making the heaviest organelles go to the bottom forming a pellet, while the rest stay
above (the supernatant). The supernatant is drained off then spun again. The organelles separate out
according to their weight.…read more

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Cholera produces a toxin choleragen which binds to the cell membrane, increasing the rate of active
transport. It causes protein channels in the plasma membrane to open. This moves way more ions into
the lumen, creating a higher concentration of ions, which means that it has a lower water potential.
This makes more water go into the lumen by osmosis which results in diarrhoea. Diarrhoea washes
sodium ions out of the digestive system.…read more


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