2.2.6 lipids 1: triglycerides

Question 1

lipids

Answer 1

group of substance soluble in alcohol (not water)
- incl. triglycerides, phospholipids, glycolipids & cholesterol

Question 2

macromolecule

Answer 2

very large, organic molecule

Question 3

phospholipid

Answer 3

molecule consisting of glycerol, 2 fatty acids & one phosphate group

Question 4

atoms in lipids

Answer 4

• lots of C & H
• smaller amounts of O

Question 5

characteristics of lipids

Answer 5

• insoluble in water
• dissolve in alcohol

Question 6

why are lipids insoluble in water

Answer 6

they are not polar so do not attract water molecules

Question 7

3 most important lipids (living things)

Answer 7

• triglycerides
• phospholipids
• steroids

Question 8

what are the 3 important lipids examples of

Answer 8

macromolecules

Question 9

triglyceride structure

Answer 9

• made of glycerol & fatty acids
• many diff. types of fatty acids

Question 10

describe what essential fatty acids are

Answer 10

the fatty acids (made within our body) that must be ingested ‘complete’

Question 11

structure of glycerol

Answer 11

• 3 carbon atoms
• alcohol = free -OH groups

Question 12

draw molecular structure of glycogen

Answer 12

check pg 61 of OCR textbook

Question 13

structure of fatty acids

Answer 13

• carboxyl group (-COOH) on 1 end
• carboxyl group attached to hydrocarbon tail = only C & H atoms

Question 14

how long can the fatty acid hydrocarbon tail be

Answer 14

2 to 20 carbons long

Question 15

why is the fatty acid structure an acid

Answer 15

the carboxyl group ionises into H+ & -COOH- group

Question 16

draw molecular structure of a (saturated) fatty acid

Answer 16

check pg 61 of OCR textbook

Question 17

what does it mean if a fatty acid is saturated

Answer 17

no C=C bonds

Question 18

what does it mean if a fatty acid is unsaturated

Answer 18

there’s a double bond between 2 of the C atoms
–> fewer H atoms bonded to molecule

Question 19

what makes a fatty acid monosaturated & example

Answer 19

single C=C bond
- eg. oleic acid

Question 20

what makes a fatty acid polysaturated & example

Answer 20

more than 1 C=C bond
- eg. linoleic acid

Question 21

what impact does having 1+ C=C bond have on the structure of a fatty acid chain

Answer 21

• changes shape of hydrocarbon chain
• gives a kink where double bond is
• kinks push molecules apart slightly = more fluid

Question 22

which lipids contain lots of saturated fatty acids

Answer 22

= animal lipids
- often solid at 20 degrees

Question 23

what does a triglyceride consist of

Answer 23

1 glycerol bonded to 3 fatty acid chains

Question 24

what happens to cause the glycerol & the fatty acids to bond

Answer 24

• condensation reaction occurs between -COOH of fatty acids & -OH group of glycerol
• water molecule produced

Question 25

what’s the name of the covalent bond that forms between the fatty acids & the glycerol

Answer 25

ester bond

Question 26

name the 5 functions of triglycerides

Answer 26

1. energy source
2. energy store
3. insulation
4. buoyancy
5. protection

Question 27

describe triglycerides function as an: energy source

Answer 27

• broken down in respiration to release energy & generate ATP
• 1st step = hydrolyse ester bonds
• then, glycerol & fatty acids able to be broken down completely to CO2 & H2O
• respiration of a lipid produces more water than respiration of sugar

Question 28

describe triglycerides function as an: energy store

Answer 28

• stored without affecting water potential of cell (as insoluble in water)
• mammals store fat in adipose cells
• 1g of fat releases 2x energy as 1g of glucose
  –> lipids have higher proportion of H atoms than carbohydrates & almost no O atoms

Question 29

describe triglycerides function as an: insulation

Answer 29

• adipose tissue is a storage location for lipid in whales (‘blubber’) = heat insulator
• lipid in nerve cells = electrical insulator
• animals prepping for hibernation store extra fat

Question 30

describe triglycerides function as an: buoyancy

Answer 30

• fat is less dense than water
• used by aquatic animals to stay afloat

Question 31

describe triglycerides function as an: protection

Answer 31

• humans have fat around delicate organs (eg. kidneys) = shock absorber
• peptidoglycan cell wall of some bacteria is covered in lipid-rich outer coat