Lipids

Question 1

give six functions of a lipid

Answer 1

• A source of energy
• Energy storage
• all biological membranes
• insulation
• protection
• some hormones
• metabolic water source

Question 2

Which element do lipids contain?

Answer 2

Carbon hydrogen and oxygen. The proportion of oxygen in lipids is very low, much lower than that found in carbohydrate.

Question 3

What is meant by the term essential fatty acid?

Answer 3

And essential fatty acid is one of bodies cannot make today must be taken in as part of the complete diet

Question 4

What is the structure of fatty acid?

Answer 4

All fatty acids have an acid group, 1 and the rest of the molecule consists of a hydrocarbon chain which can be anything from 2 to 20 carbons long

Question 5

What is meant by the term saturated fatty acid?

Answer 5

Saturated fatty fatty acid is one without any carbon carbon double bond this means that the hydrocarbon chain is straight

Question 6

What is meant by the term monounsaturated fat acid?

Answer 6

Monounsaturated fat yes it is one with only one carbon carbon double bond

Question 7

What is meant by the term polyunsaturated fatty acid?

Answer 7

Polyunsaturated fatty acid is one with multiple carbon carbon double bond so the chain has many kinks

Question 8

Describe the type of triglyceride found in animal

Answer 8

Animal lipids contain a great deal of saturated fatty acid they are solid at room temperature and are called fats.
This excludes fish which make unsaturated fatty acids

Question 9

Describe the type of triglyceride found in plants

Answer 9

Plant lipids contain more unsaturated fatty acids and they’re a liquid at room temperature, and a called oils

Question 10

What is the name of a bond formed in a triglyceride??

Answer 10

And Esther bond between the OH group of the glycerol molecule and the carboxyl end of the fatty acid molecule

Question 11

Describe the structure of a phospholipid

Answer 11

It has one glycerol molecule with two fatty acids going to this by Ester bonds. It then has a hydrophilic phospholipid head.

Question 12

What are the properties of each end of the phospholipid?

Answer 12

The phosphate head is hydrophilic, the fatty acid tails are hydrophobic.

Question 13

How do you phospholipids affect membrane fluidity?

Answer 13

Animals that live in cold climates have an increased number of unsaturated fatty acid is in the phospholipid molecules this insures that membrane to remain fluid despite the low temperatures

Question 14

What features make triglycerides excellent energy storing molecules?

Answer 14

They are in soluble in water, They can be stored in a compact way, they do not affect the water potential of the cell

Question 15

What steroid hormones are made from cholesterol?

Answer 15

Testosterone oestrogen and vitamin D

Question 16

Describe a cholesterol molecule

Answer 16

It is a class of lipid, that is made from four carbon based rings, it has a small narrow structure and a hydrophobic nature

Question 17

What are the three categories of lipids?

Answer 17

Triglycerides phospholipids and sterols

Question 18

Why do saturated triglycerides tend to be solid at room temperature?

Answer 18

Because they have straight fatty acid tails which allows them to pack closer together.

Question 19

How many water molecules would be produced when a triglyceride is broken down?

Answer 19

Three, one for each fatty acid

Question 20

How does the presence of cholesterol affect a cell membrane?

Answer 20

It regulates its fluidity, either by binding the phospholipids closer together or by creating space between them.