Unit 2 - Module 1 - Lipids

Question 0

What are the functions of lipids?

Answer 0

Energy source
Energy storage
Biological membranes
Insulation
Protection
Some hormones

Question 1

What percentage of organic matter do lipids make up?

Answer 1

5%

Question 2

What forms lipids?

Answer 2

Glycerol and fatty acids.

Question 3

What is the structure of glycerol?

Answer 3

3-carbon chain with 3 OH groups.

Propan-1,2,3-triol.

Question 4

What is the structure of the fatty acid?

Answer 4

Differ, there are essential fatty acids.

All fatty acids have a carboxyl group -COOH, with a hydrocarbon chain.

Question 5

What effect do C=C bonds have in hydrocarbon chains?

Answer 5

They change the shape pushing molecules in lipid apart.

This makes them more fluid.

Question 6

What are fats?

Answer 6

Lipids that at room temperature are solid. Often mainly saturated fatty acids.
Often animal lipids.

Question 7

What are oils?

Answer 7

Lipids that at room temperature are liquid.
Often contain many unsaturated fatty acids.
Often plant lipids.

Question 8

What is the structure of triglycerides?

Answer 8

One glycerol molecule bonded to three fatty acid molecules.

Question 9

What is the name of the bond that forms between a glycerol molecule and fatty acids?

Answer 9

An ester bond

-O-

Question 10

Why are triglycerides insoluble in water?

Answer 10

The charges in the molecule are distributed evenly around the molecule. Therefore hydrogen bonds cannot form between molecule and water, and so don’t mix.

Question 11

What is the main role of triglycerides?

Answer 11

A compact energy store.

Question 12

What is the structure of a phospholipid?

Answer 12

A glycerol molecule bonded to two fatty acids and a phosphate group.

Question 13

How do organisms control fluidity of membranes?

Answer 13

How saturated or unsaturated phospholipids are.

Question 14

What is an example of controlling fluidity of a membrane!

Answer 14

In colder climates organisms have an increased number of unsaturated fatty acids. This ensures membranes remain fluid despite low temperatures.

Question 15

How are lipids used in respiration?

Answer 15

Hydrolysis of the ester bonds.
Glycerol and fatty acids can both be broken down completely to carbon dioxide and water. This releases energy used to make ATP.

Question 16

How much energy does respiration of one gram of lipid give?

Answer 16

Twice as much energy we the respiration of one gram of carbohydrate.

Question 17

What is the structure of cholesterol?

Answer 17

Four carbon-based ring structures joined together.

Question 18

What is the main role of cholesterol?

Answer 18

Forms a small, thin molecule that fits into lipid bilayer giving strength and stability.

Question 19

What other roles does cholesterol have?

Answer 19

It is used to form steroid hormones, such as testosterone, oestrogen and vitamin D.

Question 20

Why does excess cholesterol cause problems in humans?

Answer 20

In bile cholesterol can stick together to form lumps called gallstones.
In blood can be deposited in the inner linings of blood vessels, causing atherosclerosis, which can result in circulatory problems.