Lipids

Question 1

What are the two groups of lipids

Answer 1

Triglycerides and phospholipids

Question 2

How are Triglycerides formed

Answer 2

Condensation of 1 molecule of glycerol + 3 molecules of fatty acids

Question 3

What does a condensation reaction between glycerol and a fatty acid (RCOOH) form

Answer 3

An ester bond

Question 4

Is the R-group saturated or unsaturated

Answer 4

Both

Question 5

What happens in a phospholipid compared with triglycerides

Answer 5

1 fatty acid of a triglyceride is substituted by a phosphate-containing group

Question 6

What are the different properties of triglycerides and phospholipids related to

Answer 6

Their different structures

Question 7

Features x2 of triglycerides (two words)

Answer 7

Non-polar
Hydrophobic

Question 8

What are the monomers of Triglycerides

Answer 8

Glycerol
Fatty acid

Question 9

Shorthand formula of a fatty acid

Answer 9

RCOOH

Question 10

How can fatty acids vary

Answer 10

Length of hydrocarbon chain
Saturate or unsaturated( double bond c=c)

Question 11

Are the tails hydrophilic or hydrophobic in a triglycerides

Answer 11

Hydrophobic

Question 12

If something is hydrophobic does it dissolve in water?

Answer 12

No it’s insoluble

Question 13

What type of reaction is an ester bond forming

Answer 13

Condensation

Question 14

How many ester bonds are needed to form a triglycerides

Answer 14

3

Question 15

Structure of a phospholipid

Answer 15

Phosphate group
Glycerol
2 fatty acids

Question 16

Which parts are hydrophobic and hydrophilic on a phospholipid

Answer 16

Hydrophobic tails
Hydrophilic heads

Question 17

What are triglycerides used for

Answer 17

Energy storage

Question 18

Structure/ function of triglycerides

Answer 18

Good energy storage- long hydrocarbon tails of fatty acids contain lots of chemical energy - lots of energy released when they are broken down
Insoluble in water - don’t effect osmosis

Question 19

Test for lipids

Answer 19

Emulsion
Add ethanol then add water
Forms white emulsion

Question 20

Structure of a fatty acid

Answer 20

O=C——-R
/
OH

Question 21

Why does using colorimeter improve repeatability of results

Answer 21

Standardise method

Question 22

Compare and contrast structure and properties of phospholipid and triglycerides x5

Answer 22

1. Both contain ester bonds (between glycerol and fatty acid)
2. Both contain glycerol;
3. Fatty acids on both may be saturated or unsaturated;
4. Both are insoluble in water;
5. Both contain C, H and O but phospholipids also contain P
6. Triglyceride has three fatty acids and phospholipid has two fatty acids plus phosphate group;
7. Triglycerides are hydrophobic/non-polar and phospholipids have hydrophilic and hydrophobic region;
   Accept ‘non-polar’ for hydrophobic and ‘polar’ for hydrophilic.
8. Phospholipids form monolayer (on surface)/micelle/bilayer (in water) but triglycerides don’t;

Question 23

Is cholesterol a lipid

Answer 23

Yes