Unit 1: Lipids

Question 1

why are lipids important?

Answer 1

provide long term source of energy
function as hormones
structural component of plasma membrane
provide insulation for animals
buoyancy for aquatic animals

Question 2

what is the solubility of lipids?

Answer 2

insoluble in water, soluble in organic solvents

Question 3

what are the three main groups of lipids?

Answer 3

triglycerides, phospholipids and steroids

Question 4

what are triglycerides composed of?

Answer 4

three fatty acids and a glycerol molecules by esterification

Question 5

what is glycerol composed of?

Answer 5

3 carbons and 3 OH groups

Question 6

what are fatty acids composed of?

Answer 6

a carboxylic group group at one end and a hydrocarbon tail at other

Question 7

what is the main function of a triglyceride?

Answer 7

an energy store

Question 8

what do plants and animals store energy as?

Answer 8

triglycerides as oil - plants

triglycerides as fats - animals

Question 9

what happens to triglycerides during aerobic respiration?

Answer 9

triglycerides break down to form a 2c carbon compound that is fed into the citric acid cycle as acetyl coenzyme A

Question 10

what is a saturated fatty acid?

Answer 10

has no C-C double bond, and have a very straight structure, packed closely

Question 11

what is a unsaturated fatty acid?

Answer 11

have one or more C-C double bond, kinked in structure and cannot pack closely

Question 12

what is released in the breakdown of triglycerides?

Answer 12

water

Question 13

what is a phospholipid made up of?

Answer 13

two fatty acids, phosphate group and glycerol

Question 14

what bonds joins the phosphate and the fatty acids to the glycerol?

Answer 14

an ester bond

Question 15

explain what the head and tail of the phospholipid are?

Answer 15

the head is a phosphate group - polar - hydrophilic, the tail is a long hydrocarbon group - non polar - hydrophobic

Question 16

what does cholesterol do to the membrane?

Answer 16

stiffen it

Question 17

why are unsaturated fatty acids present for membranes?

Answer 17

they add fluidity since the kinks don’t allow them to be tightly packed
allows transport of substances across the bilayer

Question 18

explain the connection between temperature and unsaturated and saturated fatty acids.

Answer 18

The colder the temperature the membrane is exposed to the more unsaturated fatty acids are present.
The warmer the temperature the more saturated fatty acids there are

Question 19

what structure do steroids have in common?

Answer 19

a 4 ring structure of 17 carbons

Question 20

why are steroids classed as lipids?

Answer 20

they are soluble in organic compounds but not water

Question 21

what makes a steroid different from another?

Answer 21

side chain

Question 22

what is the role of steroids?

Answer 22

as they can pass through the membrane, the play a part in cell signalling and hormonal function

Question 23

what additional components does cholesterol have?

Answer 23

an OH at the bottom left and an C8H17 on the top right

Question 24

what are the roles of cholesterol?

Answer 24

fit into the hydrophobic part of the phospholipid and reduces movement in the membrane
prevent solidification of the membrane at low temp

Question 25

what is the structure of testosterone?

Answer 25

has double bond O at the bottom left and an OH group at the top right

Question 26

what is testosterone important for?

Answer 26

muscle development and male puberty

Question 27

what are anabolic steroids?

Answer 27

they help build muscle or allow people to train harder