Lipids

Question 1

How is the structure of cellulose linked to its function?

Answer 1

Hydrogen bonds between chains form microfibrils which are strong.

Question 2

Draw and label a simple diagram of a triglyceride.

Answer 2

Glycerol and three fatty acids

Question 3

What is a saturated fatty acid?

Answer 3

Saturated fatty acids do not have any carbon=carbon double bonds, the hydrocarbon tail is ‘saturated’ with hydrogen atoms

Question 4

What is an unsaturated fatty acid?

Answer 4

Unsaturated fatty acids do have at least one carbon=carbon double bond in the hydrocarbon tail, causing the chain to kink.

Question 5

Name the chemical bond formed between glycerol and a fatty acid.

Answer 5

Ester bond

Question 6

Define hydrophobic and hydrophilic.

Answer 6

hydrophobic = water repelling. hydrophilic = water loving

Question 7

Which part of a triglyceride is hydrophobic?

Answer 7

fatty acid

Question 8

Describe how the structure of a triglyceride is linked to its structure.

Answer 8

Triglycerides are energy storage molecules. The hydrocarbon tails of the fatty acids contain lots of chemical energy that is released when they are broken down. They are also insoluble in water and so do not affect water potential of the cell (no osmosis).

Question 9

Describe the general structure of a phospholipid.

Answer 9

glycerol, 2 fatty acids and phosphate head.

Question 10

Describe how the structure of a phospholipid is linked to its structure.

Answer 10

Phospholipids form lipid bilayer of cell membranes (and membrane bound organelles).
Function of a cell membrane is to control what enters and leaves the cell, it does this because the hydrophilic phosphate heads face out towards water (both inside and outside of the cell) and the hydrophobic tails face inwards, forming a double layer. This means that water soluble substances can not easily pass though the middle of the bilayer - controlling movement through the membrane.