[OLD] Biological Molecules - Lipids

Question 1

What do lipids consist of?

Answer 1

The molecules glycerol joined to three fatty acids

Question 2

What is glycerol?

Answer 2

An alcohol

Question 3

What are fatty acids?

Answer 3

long hydrocarbon chains with COOH on the end

Question 4

How do fatty acids join to glycerol molecules?

Answer 4

By condensation reaction between OH groups on the glycerol and OH groups on the fatty acids.

Question 5

What bonds join fatty acids and glycerol molecules?

Answer 5

Ester bonds

Question 6

What are saturated fatty acids?

Answer 6

Fatty acids that have no double bonds between their carbons, and therefore are a straight chain

Question 7

What are unsaturated fatty acids?

Answer 7

Fatty acids that contain double bonds between their carbons, and therefore have a bends in the their chain at each double bond

Question 8

Why can’t unsaturated fatty acids pack close together?

Answer 8

The C-C double bonds create a bend in the chain at each one.

Question 9

Where do unsaturated fatty acids tend to occur?

Answer 9

In plant oils e.g vegetable oil, olive oil, sunflower oil etc

Question 10

Why are unsaturated fatty acids liquid?

Answer 10

Because they cannot pack closely together

Question 11

What are saturated fatty acids bound together by?

Answer 11

Hydrogen bonds

Question 12

What do saturated fatty acids’ straight chains allow them to do?

Answer 12

Pack closely together

Question 13

Where are saturated fatty acids found?

Answer 13

Inn animal tissues e.g butter, lard etc

Question 14

What do saturated fatty acids make?

Answer 14

Solid, saturated fats

Question 15

Why do unsaturated fats have less C-H bonds?

Answer 15

They have C=C double bonds

Question 16

Why are unsaturated fats healthier?

Answer 16

They have less C-H bonds, and it is the breaking of C-H bonds that can lead to energy release.
Therefore they have less energy in them when we break them down which makes them healthier in a calorie controlled diet.

Question 17

5 uses of lipids

Answer 17

energy store
metabolic water
thermal insulation
buoyancy
shock protection

Question 18

How are lipids used as an energy store?

Answer 18

They are insoluble in water and contain many C-H bonds that can be broken to release energy.

Question 19

How are lipids used as metabolic water?

Answer 19

Aerobically respired fats release water e.g camel’s hump

Question 20

How are lipids used as thermal insulation?

Answer 20

Deposited under skin to provide insulation e.g blubber in whales

Question 21

How are lipids used as buoyancy?

Answer 21

Fat is less dense than water, therefore can provide buoyancy to whales etc

Question 22

How are lipids used as shock protection?

Answer 22

Fat is deposited around some major organs to absorb shock e,g kidneys, heart

Question 23

How do you get phospholipids from lipids?

Answer 23

Replace one fatty acid chain with a phosphate group

Question 24

Where are phospholipids used?

Answer 24

In the phospholipid bilateral of cell membranes

Question 25

3 uses of cholesterol

Answer 25

regulates fluidity of cell membranes
precursor for steroid hormones e.g oestrogen and testosterone
precursor for vitamin D

Question 26

What does excess cholesterol cause?

Answer 26

Gall stones, atherosclerosis