Biological Molecules 3 - Lipids

Question 1

What do lipids include?

Answer 1

triglycerides and phospholipids

Question 2

What two molecules do lipids consist of?

Answer 2

glycerol and fatty acids

Question 3

Are lipids insoluble?

Answer 3

Yes but they can dissolve in organic liquids e.g. ethanol

Question 4

What is different about a lipid from a carbohydrate?

Answer 4

contains proportionally less oxygen than carbohydrates.

Question 5

What does a glycerol look like?

Answer 5

has 3 carbons, 5 hydrogens and 3 OH groups

https://www.differencebetween.com/difference-between-glycerol-and-vs-fatty-acids/

Question 6

What is the general formula of fatty acids? And give an example of what they could look like.

Answer 6

COOH.(CH2)nCH3
https://www.creative-proteomics.com/blog/index.php/biref-introduction-of-short-chain-fatty-acids/

Question 7

Give the definition of a glycerol

Answer 7

It is an alcohol that dissolves in water meaning it is a hydrophilic molecule

Question 8

Why are triglycerides not considered polymers?

Answer 8

made up of two diff. types of subunits ( glycerol and fatty acids) which have different structures.

Triglycerides aren’t made up of identical monomers.

Question 9

Are fatty acids hydrophobic or hydrophilic?

Answer 9

Hydrophobic meaning they are repelled by water.

Question 10

What does a triglyceride look like?

Answer 10

https://clinidiabet.com/en/infodiabetes/cardiodiabetes/15.htm

Question 11

How does one fatty acid differ from another?

Answer 11

By length of hydrocarbon chain (CH2n)

variation of lipid structure caused by diff. types of fatty acid

Question 12

What are the 2 types of fatty acid?

Answer 12

saturated and unsaturated

Question 13

What does the hydrocarbon chain in a saturated fatty acid consist of?

Answer 13

no carbon-to-carbon double bonds

is a straight solid hydrocarbon chain

has the maximum no. of hydrogen atoms bonded to the carbon atoms, hence the term saturated.

Question 14

What is does a unsaturated fatty acid hydrocarbon chain consist of?

Answer 14

one or many (mono/poly) carbon-to-carbon double bonds

chain is kinked where there is a double C bond so is more of a fluid/liquid

doesn’t contain max. no. of H atoms since C has used one of its bonds to double bond with another C, hence the term unsaturated

Question 15

How is a triglyceride formed and broken? (6 points)

Answer 15

one glycerol molecule combines with three fatty acid molecules

there is an ester bond between the fatty acid and glycerol

one triglyceride will therefore have 3 ester bonds

ester bonds are formed by condensation reactions

water formed from the H in the OH group on glycerol and full OH group from COOH unit from the fatty acid

if a lipid is broken down, it undergoes a hydrolysis reaction.

Question 16

Which type of fat can damage the heart and coronary arteries and contribute to heart disease?

Answer 16

saturated fat

Question 17

What is a low-density lipoprotein? (LDL)

Answer 17

contain and transport saturated fat causing harm

this fatty material can block major arteries (plaque), and can cause myocardial infarction (heart attack)

Question 18

What is a high density lipoprotein (HDL)?

Answer 18

contain and transport unsaturated fats carrying harmful fats away to the liver for disposal

high proportion of HDL in blood lowers risk of heart disease

Question 19

What health implications that high fat intake cause?

Answer 19

atherosclerosis, aneurysm, and myocardial infarction

Question 20

What does an aneurysm do?

Answer 20

damages the thin artery wall by inflation. the artery can’t handle the pressure and blood cant get away from the heart

Question 21

what are the properties of lipids?

Answer 21

insoluble in water but soluble in organic solvents
fats are solid at room temp.
oils are liquid at room temp.

Question 22

Give the 6 functions of lipids and describe each of them.

Answer 22

Energy storage - in seeds and animals, release more energy than carbohydrates when used as an alternative respiratory substrate
Protection of vital organs - used as shock absorption, preventing physical damage to internal organs
Thermal insulation - used as heat insulator e.g blubber in whales, seals and polar bears
Buoyancy - lipids are less dense than water so they float, they have a role in maintaining buoyancy in organisms such as fish
Metabolic water - produced when lipids are oxidised by respiration, vital in desert animals such as camels whose hump is made of fat.
Waterproofing - waxes are hydrophobic and cover the exoskeleton of insects and cuticles of plant leaves, reducing water loss

Question 23

What are phospholipids made of?

Answer 23

they have glycerol, two fatty acids and a phosphate group

Question 24

Which part of the phospholipid is hydrophilic? And which is hydrophobic?

Answer 24

The phospholipid head - including glycerol and phosphate group.
Fatty acid tails