OCR Biology AS: Unit 2 Module 1 Ch 10 and 11 LIPIDS

Revision sheet for Lipids.

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Preview of OCR Biology AS: Unit 2 Module 1 Ch 10 and 11 LIPIDS

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Lipids unlike proteins, carbohydrates and nucleic acids, do not form polymers. They are large molecules with few oxygen atoms and many carbon and hydrogen
atoms.
This means they have low melting points; in living organisms are often in liquid form, they are hydrophobic, therefore insoluble in water and they are less dense than
water.
Triglycerides Phospholipids Cholesterol and Steroid hormones
Phospholipids have a similar structure to triglycerides,
but with a PHOSPHATE in place of one fatty acid
chain. There may also be other groups attached to the
phosphate. Phospholipids have a polar hydrophilic "
head" (the negatively-charged phosphate group) and
two non-polar hydrophobic "tails" (the fatty acid chains)
This mixture of properties is fundamental to biology, for
phospholipids are the main components of cell
membranes.
- Cholesterol is a lipid
- Not formed from fatty acids and glycerol
- Small molecule made from FOUR carbon-based ring
- It is found in all biological membranes.
Functions:
Its small, narrow structure and hydrophobic
2 components: 1 Glycerol (POLAR - OH Groups)
nature allow it to sit between the phospholipid
3 Fatty Acids (POLAR ­ OH Groups)
hydrocarbon tails and help to regulate the fluidity and
Saturated (no
strength of the membrane.
Double bond)
-solid at room
Make bile salts in the gall bladder
Temp. Make steroid hormones eg testosterone ­ can
-animal fats pass directly from the phospholipid bilayer in order
to reach their target receptor ­ usually inside the
nucleus ­ nuclear envelope
Unsaturated
(double bond) Make vitamin D
-liquid at room)
Temp Excess cholesterol may be a problem in humans beca
-olive oil
(mono) ` In bile, cholesterol can stick together to form lumps
-sunflower called gall stones
(poly) ` In blood, cholesterol can be deposited in the inner
linings of blood vessels causing atherosclerosis,

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Animals cannot make some of the fatty acids they need from
The raw materials taken into their bodies these are called
ESSENTIAL FATTY ACIDS, they must be taken in as a part
Of the diet.
i) Organisms that live in cold environments have more FAMILIAL HYPERCHOLESTEROLAEMIA (FHC)
Unsaturated fatty acids in their membranes.…read more

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