Lipids

Question 1

what elements do lipids contain?

Answer 1

carbon, hydrogen and oxygen

Question 2

which have less oxygen lipids or carbohydrates?

Answer 2

lipids

Question 3

are lipids polar or non-polar?

Answer 3

non-polar

Question 4

are lipids soluble in water?

Answer 4

no

Question 5

what will lipids dissolve in?

Answer 5

organic solvents such as alcohol

Question 6

Due to lipids being non-polar and insoluble in water what are they described to be?

Answer 6

hydrophobic

Question 7

what 2 molecules are lipids made up of?

Answer 7

fatty acids and glycerol

Question 8

what are the names of the 2 types of lipids?

Answer 8

triglycerides and phospholipids

Question 9

what are fatty acids?

Answer 9

• long chains of carbon and hydrogen atoms
• carboxyl group at one end (COOH)

Question 10

what is a saturated fatty acid?

Answer 10

contains no c=c bond

Question 11

what is an unsaturated fatty acid?

Answer 11

contains at least 1 c=c bond
- 1 c=c bond is monosaturated
- 2+ c=c bond is polysaturated

Question 12

what is the structure of a saturated fatty acid?

Answer 12

straight shape so they can be tightly packed, therefore they’re solid

Question 13

what’s the structure of an unsaturated fatty acid?

Answer 13

the chain kinks where the c=c bond is so they can’t be packed as tightly therefore they’re in a liquid state

Question 14

what are triglycerides made up of?

Answer 14

3 fatty acids and 1 glycerol

Question 15

what bonds attach the fatty acids to the glycerol?

Answer 15

ester bonds via a condensation reaction (remove 3 water)

Question 16

what does the condensation reaction on a triglycerides occur between?

Answer 16

the carboxyl group (COOH) on the fatty acid and the hydroxyl group (OH) on the glycerol

Question 17

why are triglycerides a good energy storage?

Answer 17

lots of C-H bonds that store lots of energy

Question 18

how can triglycerides act as a metabolic water source?

Answer 18

they release water when they’re oxidised

Question 19

why is the fact that lipids are large and hydrophobic an advantage?

Answer 19

they won’t effect the water potential and osmosis in a cell

Question 20

why is it good lipids are low in mass?

Answer 20

a lot can be stored in an animal without increasing mass

Question 21

what are phospholipids made up of?

Answer 21

a glycerol, 2 fatty acids and a phosphate group

Question 22

how do the 2 fatty acids bond to the glycerol?

Answer 22

via 2 condensation reactions (release 2 water molecules) forming 2 ester bonds

Question 23

what’s the phosphate molecule described as?

Answer 23

• hydrophilic head (towards the water as it is charged)
• as it’s charged it repels other fats

Question 24

what’s the fatty acid chain described as?

Answer 24

the hydrophobic tail as it repels water but will mix with fats

Question 25

what’s is a phospholipid described as?

Answer 25

polar due to the 2 regions acting differently

Question 26

how are phospholipids positioned?

Answer 26

the heads are exposed to water
the tails are away from the water

Question 27

what does the movement in a phospholipid form?

Answer 27

a phospholipid bilayer which forms the plasma membrane around cells
- hydrophilic phosphate head enables the surface of the plasma membrane to stay in place

Question 28

why is the phospholipid bilayer arrangement an advantage?

Answer 28

enables carbohydrates to attach and form important receptors on the membrane (glycolipids)

Question 29

how would you test for the presence of a lipid?

Answer 29

1. Add 2cm3 of the sample to a test tube
2. Add 5cm3 of ethanol and shake to dissolve the sample
3. Add 5cm3 of water and shake
   Positive Result = cloudy-white solution