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Cells and movement in and out of them


We use microscopes to magnify the image of an object that is not visible to the naked eye. An
object is a material you put under a microscope and the image is the appearance of this object
when viewed through the…

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This is the process by which the fragments in the filtered homogenate are separated in an
ultracentrifuge. This machine spinds tubes of homogenate at a high speed in order to create a
centrifugal force. For animal cells, the process is as follows:

The tube of filtrate is placed in…

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A complex `staining' process is required and even then the image is in black and white.
The specimen must be extremely thin
The image may contain artefacts (things that result from the way the specimen is
prepared, not what you're observing) however improvements in technique can eliminate
most of these.…

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production of their own proteins. The enzymes involved in respiration are found in the

Mitochondria are responsible for the production of the energy-carrier molecule ATP, from
carbohydrates. Because of this, the number of mitochondria increases in cells that have a high
level of metabolic activity and therefore need a…

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The functions of lysosomes are to:

Break down material ingested by phagocytic cells, such as white blood cells
Release enzymes to the outside of the cell (exocytosis) to destroy material around the cell
Digest worn out organelles so that the useful chemicals they are made of can be re-used

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Rough Extensive Collects, stores,
endoplasmic membrane system packages and
reticulum with ribosomes transports the
attached. proteins made on the
Connected to ribosomes.
nuclear membrane.

Smooth Membrane system Systhesis of lipids and
endoplasmic with no ribosomes some steroids.
reticulum attached. Occurs in
small patches in
the cytoplasm.

Golgi Stack of flattened…

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As the glycerol molecule in all triglycerides is the same, the differences in the properties of the
different fats comes from variations in the fatty acids.

Phospholipids are similar to lipids except that one of the fatty acid molecules has been replaced by
a phosphate molecule. Phosphate molecules (head)…

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There are a number of factors that affect the rate at which diffusion takes place:

Concentration gradient ­ the greater the difference in concentration of the molecules or
ions, the faster the rate of diffusion
Area over which diffusion takes place ­ the larger the area of an exchange…

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The highest value for water potential, that of pure water, is zero, and so all other values are

Animal cells contain a variety of solutes dissolved in their cytoplasm. To prevent water moving in
or out via osmosis, animal cells are normally bathed in a liquid which has…

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Active transport

Metabolic energy in the form of ATP is needed
Carrier protein molecules which act as `pumps' are involved
Selective process

Direct active transport of a single molecule or ion:

Carrier proteins span the cell surface membrane and accept the molecules/ions to be
transported on one side of it.…


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