Lipids

Question 1

What are 2 main groups of lipids?

Answer 1

Triglycerides
Phospholipids

Question 2

What are the 3 elements lipids are made up of?

Answer 2

Carbon
Hydrogen
Oxygen

Question 3

Do lipids contain a lower proportion of oxygen compared to carbohydrates?

Answer 3

Yes

Question 4

What are triglycerides made up of?

Answer 4

1 glycerol
3 fatty acids

Question 5

Why are triglycerides not considered to be polymers?

Answer 5

Made up of 2 different types of subunit (glycerol and fatty acids)
Have different structures
Are not made from identical monomers

Question 6

What is the general formula for glycerol?

Answer 6

C3H8O3

Question 7

Is glycerol constant in both triglycerides and phospholipids?

Answer 7

Yes

Question 8

What are the 3 main components of fatty acids?

Answer 8

Methyl group (CH3)
Long hydrocarbon chain (CH2)
Carboxyl group (COOH)

Question 9

What are constant and what is the variable in fatty acids?

Answer 9

Methyl group - constant
Hydrocarbon chain - variable
Carboxyl group - constant

Question 10

What are the properties of saturated fatty acids?

Answer 10

Are solid at room temperature
Contain no carbon to carbon double bonds
Has a straight chain hydrocarbon chain
Has the maximum number of hydrogen atoms bound to the carbon atoms in the hydrocarbon chain

Question 11

What are the properties of unsaturated fatty acids?

Answer 11

Oils at room temperature
1 or more carbon to carbon double bonds
Does not contain the maximum number of hydrogen atoms

Question 12

How is a triglyceride formed?

Answer 12

1 glycerol + 3 fatty acids = triglyceride
Each fatty acid is bonded to the glycerol by an ester bonds
Has 3 ester bonds in total

Question 13

What can a high intake of fat lead to?

Answer 13

Damages heart and coronary arteries
Contributes to heart disease

Question 14

What are low density lipoproteins (ldl’s)?

Answer 14

Contain and transport saturated fats and cause harm
Fatty material can block major arteries (plaque)
Cause a myocardial
Infarction (heart attack)
Stick to the lining of the vessel

Question 15

What are high density lipoproteins (hdl’s)?

Answer 15

Contain and transport unsaturated fats
Carry harmful fats away to the liver for disposal
Higher proportion of HDL in the blood lowers the risk of heart disease
Removes ldl’s from blood to the liver

Question 16

What health implication can occur because of a high fat intake?

Answer 16

Atherosclerosis
Aneurysm
Myocardial infarction

Question 17

Are lipids soluble or insoluble in water?

Answer 17

Insoluble in water
Soluble in organic solvents (acetone/ethanol)

Question 18

What are the main 6 functions of lipids?

Answer 18

Energy storage
Protection of vital organs
Thermal insulation
Buoyancy
Metabolic water
Waterproofing

Question 19

How does energy storage help with the function of lipids?

Answer 19

Used as an energy storage in seeds and animals
Release a lot more energy than carbohydrates
Used as alternative respiratory substrates

Question 20

How does the protection of vital organs help with the function of lipids?

Answer 20

Used as ‘shock absorption’
Prevent physical damage to internal organs

Question 21

How does thermal insulation help with the function of lipids?

Answer 21

Slow conductor of heat
Examples - blubber in whales, seals and polar bears
Lipids reduces heat loss

Question 22

How does buoyancy help with the function of lipids?

Answer 22

Lipids are less dense than water
Float and have a role in maintaining buoyancy in organisms
Examples - fish

Question 23

How does metabolic water help with the function of lipids?

Answer 23

Production of metabolic water occurs when lipids are oxidised by respiration
Important to desert animals
Example - camels whose hump is made of fat

Question 24

How does waterproofing help with the function of lipids?

Answer 24

Waxes are hydrophobic
Cover the exoskeleton of insects and cuticle of plant leaves
Provide a waterproofing property
Reduce water loss

Question 25

What are phospholipids?

Answer 25

Has 1 glycerol, 2 fatty acids and a phosphate group attached to the glycerol

Question 26

Which part of the phospholipids is hydrophobic and hydrophilic?

Answer 26

Fatty acid tail - hydrophobic
Polar head group - hydrophilic

Question 27

What is the main function of phospholipids?

Answer 27

Important component of cell membranes
Helps control the inflow and outflow of substances
Due to the presence of hydrophobic fatty acid tails, a hydrophobic core is created when a phospholipid bilayer forms
Acts as a barrier to water-soluble molecules

Question 28

Describe the structure of phospholipids

Answer 28

Are amphipathic (both hydrophobic & hydrophilic)
Phospholipids form monolayers/bilayers in water