LIPIDS Flashcards

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1
Q

What is a lipid

A

Macromolecules which contain carbon, hydrogen and oxygen atoms. However, unlike carbohydrates lipids contain a lower proportion of oxygen

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2
Q

Are lipids polar/hydrophobic

A

Non-polar and hydrophobic (insoluble in water)

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3
Q

Two types of lipid

A

There are two groups of lipid that you need to know:
Triglycerides (the main component of fats and oils)
Phospholipids

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4
Q

What are triglycerides

A

Triglycerides
Are non-polar, hydrophobic molecules
The monomers are glycerol and fatty acids

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5
Q

What is glycerol

A

Glycerol is an alcohol (an organic molecule that contains a hydroxyl group bonded to a carbon atom)

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6
Q

What so fatty acids contain at one end

A

Fatty acids contain a methyl group at one end of a hydrocarbon chain known as the R group (chains of hydrogens bonded to carbon atoms, typically 4 to 24 carbons long) and at the other is a carboxyl group

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7
Q

formula for fatty acid

A

The shorthand chemical formula for a fatty acid is RCOOH

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8
Q

What about fatty acids can vary

A

Fatty acids can vary in two ways:
Length of the hydrocarbon chain (R group)

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9
Q

Two types of chain

A

The fatty acid chain (R group) may be saturated (mainly in animal fat) or unsaturated (mainly vegetable oils, although there are exceptions e.g. coconut and palm oil)

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10
Q

what makes it mono or poly unsaturated

A

Unsaturated fatty acids can be mono or poly-unsaturated:

If H atoms are on the same side of the double bond they are cis-fatty acids and are metabolised by enzymes

If H atoms are on opposite sides of the double bond they are trans-fatty acids and cannot form enzyme-substrate complexes, therefore, are not metabolised.

They are linked with coronary heart disease

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11
Q

How are triglycerides formed

A

Triglycerides are formed by esterification
An ester bond forms when a hydroxyl (-OH) group on glycerol bonds with the carboxyl (-COOH) group of the fatty acid:
An H from glycerol combines with an OH from the fatty acid to make water
The formation of an ester bond is a condensation reaction

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12
Q

What is released during condensation

A

For each ester bond formed a water molecule is released

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13
Q

How many water released by glycerol to fatty acid

A

Three fatty acids join to one glycerol molecule to form a triglyceride
Therefore for one triglyceride to form, three water molecules are released

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