Bio Molcules Lipids

Question 1

Name the two types of lipids

Answer 1

Triglycerides

Phospholipids

Question 2

What 4 molecules react to form a triglyceride?

What reaction?

Answer 2

One glycerol

Three molecules of fatty acids

Question 3

The fatty acid is known as what

Answer 3

RCOOH

Question 4

A condensation reaction between glycerol and fatty acid forms what bond

Answer 4

Ester bond

Question 5

What is an R group

Answer 5

A long hydrocarbon chain

Question 6

What is the general formula for a carboxylic acid group

Answer 6

COOH

Question 7

What three elements do lipids contain

Answer 7

Carbon
Hydrogen
Oxygen

Question 8

Lipids contain a higher proportion of what element compared to carbohydrates?
Lipids also contain higher proportions of what element compression to carbohydrates

Answer 8

Lower proportion of oxygen

Higher proportion of hydrogen

Question 9

What two ways are lipids used

Answer 9

Respiration

Structural and storage units

Question 10

Why are lipids ideal storage compounds?
Think energy
And ideal storage compound

Answer 10

Yield twice as much energy as carbohydrates when fully oxidised

Insoluble and so osmotically inactive

Question 11

Are lipids soluble in water?

What are they soluble in?

Answer 11

Insoluble in water

Soluble in organic solvents eg alcohol

Question 12

Why do fatty acids have the general formula R COOH

Answer 12

R for the r group

COOH is the carboxylic acid group

Question 13

The R group of a fatty acid can be —————— or —————

Answer 13

Unsaturated

Saturated

Question 14

If the R group of a fatty acid is saturated what does this means about the bonds between the carbon atoms

Answer 14

No double bonds between the carbon atoms and no more hydrogen atoms can be accepted

Question 15

What does is mean if the R group is unsaturated

Answer 15

Contains one or more double bonds between the carbon atoms

Question 16

2 ways the lipids can be hydrolysed

Answer 16

Heating with acid or alkali

Using enzyme LIPASE at an optimum temperature and pH

Question 17

What is the emulsion test for lipids?

4

Answer 17

Add 2cm of ethanol to sample
Shake so the fat dissolves
Add this to water in another tube and mix
A white emulsion of fat droplets indicates lipids is present

Question 18

What is the difference between a triglycerides and a phospholipid

Answer 18

In a phospholipid one of the fatty acid is replaced by a phosphate containing group

Question 19

What is a phospholipid consist of?

What reaction?

Answer 19

One phosphate containing group
3 fatty acid
Glycerol
Joined in a condensation reaction

Question 20

The phospholipid head containing the phosphate group is what to water

Answer 20

Hydrophilic head attracts water

Question 21

The fatty acids the tail of the are what to water

Answer 21

Hydrophobic and so repel water

Question 22

What does the phospholipid head contain?
Is this polar or non polar?
Does it attract if repel water?

Answer 22

Phosphate contains group
Polar molecule
Hydrophilic and so attracts water

Question 23

What does the phospholipid tail contain?
Is this polar or non polar?
Does it attract if repel water?

Answer 23

Fatty acids
Non polar
Hydrophobic and repel water

Question 24

A thin layer of phospholipids in contact with ——— for a single ——-.
Why?

Answer 24

Water
Layer
As the polar hydrophilic heads are attracted to the water whereas the hydrophobic
tails are water repellent and project outwards

Question 25

How are phospholipids presented in the cell membrane

Answer 25

In two layers of phospholipids

The hydrophobic tails are attracted to each other and from away from water