Lipids

Question 1

Define lipids.

Answer 1

a group of substances that are soluble in alcohol rather than water.

Question 2

What is a macromolecule?

Answer 2

A very large organic molecule.

Question 3

What is the structure of a triglyceride?

Answer 3

one molecule of glycerol with three fatty acids attached by ester bonds.

Question 4

What is a saturated fatty acid?

Answer 4

there are no carbon-carbon double bonds in the molecule.

Question 5

What is an unsaturated fatty acid?

Answer 5

there is a double bond between two of the carbon atoms which means that fewer hydrogen atoms can be bonded to the molecule.

Question 6

How does an ester bond form?

Answer 6

a condensation reaction ( take out a water molecule)

Question 7

What are the properties and function of triglycerides?

Answer 7

mainly used for energy storage in molecules. They are good for storage because the long hydrocarbon tails of the fatty acids contain lots of chemical energy so a lot of energy is released when they’re broken down.

they are also insoluble. This is because the fatty acid tails are hydrophobic and face inwards, shielding themselves from water with their glycerol heads

storage molecules also need to be insoluble because otherwise they’d just dissolve and release whatever they were holding whenever they came into contact with water.

Question 8

What is the structure of a phospholipid?

Answer 8

one molecule of glycerol with 2 fatty acids attached to it and a phosphate group.

Question 9

What are the functions and properties of phospholipids?

Answer 9

found in the cell membrane
phospholipid heads are hydrophillic whereas their tails are hydrophobic so they form a double layer with their heads facing outwards to the water on each side.

the centre of the bilayer is hydrophobic so water soluble substances can’t pass through

Question 10

What is the structure of cholesterol?

Answer 10

it has a hydrocarbon ring structure attached to a hydrocarbon tail. The ring structure has a polar hydroxyl group attached to it.

Question 11

What are the functions and properties of cholesterol?

Answer 11

helps strengthen the membrane by interacting with the bilayer

is small and flat so can fit between phospholipid molecules in the membrane. They bind to the hydrophobic tail of the phospholipids, causing them to pack more closely together.

this helps to make the membrane less fluid and more rigid.