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Revision Cells, Exchange and Transport

Module 1: Cells

1.1.1. Cell Structure

a) Using a light microscope, magnification of 1500X is possible, with a resolution of around 200nm.
With a transmission electron microscope, magnifications of 2,000,000X are possible, with a resolution of
around o.o5nm. With a scanning electron microscope, magnifications of…

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Nucleus ­ Contains nucleoplasm, which contains chromosomes. Chromosomes are made from DNA,
attached to proteins. These form chromatin. The nucleus controls cellular activity by regulating chemical
reactions. It is also involved in the synthesis of proteins and enzymes. When replicating, the nucleolus
makes rRNA and assembles ribosomes.

Nucleolus ­ Essentially…

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The Golgi apparatus also plays a role in the intercellular transport of lipids. Lysosomes are formed here too.
These organelles are surrounded by a membrane containing digestive enzymes which are used to break
down old organelles in the cell.

Ribosomes are small structures (200nm in diameter) that are made from…

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Glycoproteins are found in the outer layer, with carbohydrate portions contributing to the glycocalyx.
Glycolipids which have carbohydrates attached to them (glycocalyx) extend into the intercellular space.
Cholesterol is sometimes found in the bilayer with polar groups near phospholipid polar groups.

Microtubules are straight, unbranched, hollow structures of diameter 20-25nm.…

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RER ­ Synthesis of ribosomes; transport of proteins.
SER ­ Transport of proteins and lipids, lipid synthesis: makes vesicles.
Golgi apparatus ­ Makes vesicles, adds carbohydrates to proteins (modification).
Ribosomes ­ Makes proteins by joining amino acids.
Mitochondria ­ Release energy for the cell (ATP) as respiration is carried out.…

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The cell wall is rigid and composed of murein (polysaccharide chains linked by peptides forming a strong, complex 3D
network). Slime capsule or layer outside the cell wall in some cases.




Pilli or fimbriae are flamentous structures attached to the cell wall or slime capsule.
Flagella can be found as…

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1.1.2 Cell Membranes

The cell surface membrane is not simply a `sack' created to hold all of the cytoplasm and organelles. It is a very
important structure which functions to allow certain substances to enter or leave the cell. It can `pump' other
substances into the cell against the concentration…

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The plasma membranes of the cells in a growing shoot contain receptors that allow them to detect the molecules
that regulate growth.
Muscle cell membranes contain a large number of the channels that allow the rapid uptake of glucose to provide
energy for muscle contraction.
The internal membranes of chloroplasts…

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Some (extrinsic) proteins partially embedded in the bilayer on the inside or the outside face; other (intrinsic)
proteins completely spanning the bilayer.




Glycoproteins and glycolipids


Some of the phospholipid molecules making up the bilayer, and some of the proteins found in the membrane, and
also have a small carbohydrate part…

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Membrane receptor proteins serve as connection between the cell's internal and external environments.
Transport proteins play an important role in the maintenance of concentrations of ions. These transport proteins
come in two forms: carrier proteins and channel proteins.


Membranes and Temperature


Increasing temperature gives molecules more kinetic energy, so they…

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