Lipids

Question 1

What are lipids made up of

Answer 1

carbon, hydrogen and oxygen

Question 2

What are the proportions of oxygen to carbon to hydrogen in lipids compared to carbohydrates?

Answer 2

Carbohydrates:
1:2:1
Lipids:
10:2:19
C:H:O

Question 3

What does hydrophobic mean, and what does this mean when oils are mixed with water?

Answer 3

Nonpolar.
Insoluble and repels water molecules.
It will not form a solution with water, and will rather bunch up

Question 4

What lipid is found in cell membranes

Answer 4

Phospholipid

Question 5

What lipid is an important component of cell membrane?

Answer 5

Steroid (eg cholesterol)
Look up diagram

Question 6

What is the ‘E’ shaped lipid

Answer 6

Triglyceride

Question 7

What is the backbone of the triglyceride

Answer 7

Glycerol

Question 8

What is the name of the three molecules that are attached to the backbone of triglycerides?

Answer 8

Fatty acids

Question 9

How do you simply draw a triglyceride in shorthand

Answer 9

R
|
HO-C=O

Question 9

How many different fatty acids are there

Answer 9

Over 70

Question 10

How do different fatty acids differ

Answer 10

By the hydrocarbon tail

Question 11

What are saturated fatty acids saturated with?

Answer 11

Hydrogen

Question 12

How can you tell the difference between a saturated and unsaturated fatty acid?

Answer 12

Saturated has no C=C, unsaturated does have a C=C in their fatty acid tail

Question 13

What effect does the structure of an unsaturated fatty acid have on the state of the fat at room temperature

Answer 13

It has a kink, and is therefore liquid at room temperature as the kink means there is more space between molecules

Question 14

Sources of saturated fat

Answer 14

Butter, cheese, meat, whole milk, yoghurt, pies (linked with heart disease)

Question 15

Sources of monounsaturated fat

Answer 15

Olives, rapeseed, nuts, peanuts, avocados and their oil

Question 16

Sources of polyunsaturated fat

Answer 16

Fish, walnuts, soybean, flaxseed and oil

Question 17

Monounsaturated vs polyunsaturated fats

Answer 17

Monounsaturated has one C=C, polyunsaturated has multiple

Question 18

What type of reaction creates triglycerides

Answer 18

Condensation (the process is called esterification)

Question 19

How many reactions are needed to form a triglyceride?

Answer 19

3

Question 20

What type of bond holds together triglycerides

Answer 20

Ester

Question 21

Can you draw esterification?

Answer 21

fasddas fdmaybe

Question 22

Properties of saturated triglycerides

Answer 22

• No double bonds (only single bonds)
• Solid at room temperature
• Higher melting points than unsaturated fats
• Usually derived from animal fats

Question 23

Properties of unsaturated triglycerides

Answer 23

• One or more fatty acids have 1+ double bonds
• Usually liquid at room temperature (so are oils)
• Lower melting points than saturated fats
• Usually derived from plants

Question 24

Why are lipids an excellent source of energy

Answer 24

HIgher number of energy storing carbon-hydrogen bonds

Question 25

What makes lipids a good storage molecule

Answer 25

A low mass to energy ratio means much energy can be stored in a small volume

Question 26

Why are lipids useful to camels

Answer 26

Due to the high ratio of hydrogen to oxygen atoms, they can be oxidised to produce metabolic water, useful for metabolic reactions

Question 27

Why do lipids not dissolve in water, and why is this an advantage?

Answer 27

They are large and non polar, meaning that they can be stored without affecting osmosis

Question 28

What are lipids role in waterproofing?

Answer 28

They form the waxy cuticle, preventing water from entering/exiting a plant

Question 29

What are lipids role in thermal insulation?

Answer 29

They form blubber, which stops heat from escaping eg a polar bear

Question 30

What are lipids role in protection?

Answer 30

Fat can form a protections layer eg around the kidney

Question 31

How to draw a phospholipid

Answer 31

Draw it >:(

Question 32

HOw is a phospholipid formed

Answer 32

When an inorganic phosphate ions (cells contain high levels of) replace a fatty acid in a triglyceride

Question 33

Phospholipids are comprised of and found in

Answer 33

A hydrophilic phosphate heat (soluble) and two hydrophobic fatty acid tails (repel water) A key component of cell membranes

Question 34

How are phospholipids similar to triglycerides

Answer 34

Both have fatty acid groups

Question 35

How are phospholipids different to triglycerides

Answer 35

They have a phosphate group

Question 36

Test for lipids

Answer 36

Emulsion test Mix 2cm3 of the sample with 5cm3 of alcohol (ethanol) in a dry, grease free test tube Decant mixture into 5cm3 of water White emulsion = positive Clear = negative (lipids are insoluble in water but soluble in alcohol)