Lipids.

Question 1

Gylcerol formula.

Answer 1

C3H8O3.
DIAGRAM.

Question 2

Fatty acid tail formula.

Answer 2

At beginning, O=C-OH.
CH2 for each new tail.
CH3 at the end.
DIAGRAM.

Question 3

Trigylceride properties.

Answer 3

One glycerol molecule.
Three molecules of fatty acids.
Fatty acid component can vary but glycerol always the same.

Question 4

Formation of a triglyceride.

Answer 4

Fatty acids join to glycerol through a condensation reaction.
3 molecules of water are removed.
Ester bonds are formed between glycerol and fatty acids.
By product= 3H2O.
O-C=O is an ester bond.
3 reactions/3 ester bonds/3 water molecules for each triglyceride.
Lose hydrogen from glycerol and OH from the fatty acid= 3H2O.
Hydroxal from glycerol reacts with carboxyl group from fatty acid.
DIAGRAM.

Question 5

Hydrolysis definition.

Answer 5

Water is chemically inserted in order to split up the H2O formed in the condensation reactions.

Question 6

Saturated fatty acids.

Answer 6

• If the hydrocarbon chain has only single C-C bonds.
• All Carbon atoms are linked to the maximum possible numbers of Hydrogen atoms= saturated with hydrogen atoms.
• Chain= A straight zig-zag.
• Molecules can align easily so solid at room temp, more packing, strong attraction between fatty acid tails, regular pattern of CH2, fit readily.
• Found in animal lipids.
• Useful for storage in animnals.
  DIAGRAM.

Question 7

Unsaturated fatty acids.

Answer 7

• Carbon-Carbon bond is not a single bond.
• Mono= 1 double bond between Carbons.
• Poly= more than 1 double bond between Carbons.
  DIAGRAMS.
• Kink in the chain.
• Molecules cannot align uniformly/less packing/less attraction/irregular CH2 pattern so don’t solidify readily and usually liquid at room temp.
• Plant fats.
• Higher number of carbons= higher melting point.

Question 8

What are steroid hormones made of?

Answer 8

Fats.

Question 9

Uses of phospholipids.

Answer 9

• In biological membranes.
• Electrical insulation, myelin sheath surrounding axon on nerve cells.

Question 10

Uses of triglycerides.

Answer 10

• Energy reserves in plants and animals (more C-H bonds than carbs so store more energy).
• Thermal insulation.
• Protection of delicate internal organs.
• Metabolic water (water released during chemical reactions in the body, lots produced by triglycerides when oxidised).

Question 11

Uses of waxes.

Answer 11

• Waterproofing (reduce water loss in insect exoskeletons or cuticle of plants).
• Buoyancy (less dense than H2O).

Question 12

Phospholipid structure.

Answer 12

2 fatty acid tails (hydrophobic), Glycerol, Phosphate group (PO4-).
Glycerol+Phosphate group=Phosphate/polar head.
DIAGRAM.

Question 13

Properties of phosphate head.

Answer 13

Polar= hydrophilic= interacts with water= soluble in water.
Lots of O atoms= polar.

Question 14

Fatty acid tails properties.

Answer 14

• Hydrophobic.
• Non-polar.
• Does not interact with water.
• No oxygen atoms= non-polar.

Question 15

Glycerol properties.

Answer 15

Polar.
Hydrophilic.
Interacts with water/soluble.

Question 16

Structure of phospholipids in cell membrane.

Answer 16

Phosphate head faces outwards.
Fatty acid tails face in.
Out towards the cytoplasm where the phosphate head interacts with the water as it is polar.
Bi layer going all around the cell.
DIAGRAM.

Question 17

Hydrophobic explanation.

Answer 17

Non-polar.
Does not interact with water.
E.g. Phospholipid tails.
Ethanol.
Cl2.
- Equal distribution of electrons.
- No difference in charge.
Non-polar molecules will interact with other no-polar molecules.

Question 18

Hydrophilic explanation.

Answer 18

Polar.
Does interact with water.
E.g. Phosphate head.
Water.
O= delta (partially) negative.
H= delta (partially) positive.
-Unequal distribution of electrons.
- Greater pull= slightly negative= delta-.
Polar molecules interact with other polar molecules.

Question 19

Test for lipids.

Answer 19

Emulsion test:
1) Mix sample with absolute ethanol, which dissolves any lipids present.
2) Shake with an equal volume of water.
3) Dissolved lipids come out of the solution because they are insoluble in water.
4) Forms an emulsion= cloudy, white sample.

Positive (contains lipids)= white emulsion/precipitate formed.
Negative (does not contain lipids)= no emulsion/precipitate formed.

Question 20

Cholesterol uses.

Answer 20

In cell membrane:
- Regulates/ controls the fluidity of the cell membrane (holds in place or makes it move).
- Gets transported in the blood via 2 ways (HDL or LDL).

Question 21

LDL.

Answer 21

Low density lipoproteins.
‘Bad cholesterol’.
Deposits cholesterol in the arteries= narrows arteries= high blood pressure.
Coronary heart disease (builds up in coronary heart disease)(stroke?).
Diet high in saturated fat= high levels of LDL build up.
Fatty material (atheroma) gets deposited in the coronary arteries.
Restricts blood flow and Oxygen delivery to the heart.
Completely blocked vessels= myocardial infarction/angina/heart attack.

Question 22

HDL.

Answer 22

High-density lipoproteins.
‘Happy cholesterol’.
Removes cholesterol from blood/removes built up LDL/cholesterol from arteries.
Diet high in unsaturated fats= high HDL levels in blood.
Carries harmful fats away from arteries to liver for disposal.
Higher ratio of HDL:LDL in blood= lower risk of cardio-vascular and coronary heart disease.

Question 23

Atherosclerosis.

Answer 23

Fatty deposits in coronary arteries.

Question 24

Hypertension.

Answer 24

High blood pressure.

Question 25

When are lipoproteins made.

Answer 25

After food is absorbed at the small intestine, lipids and proteins combine to make lipoproteins then travel around the body in the blood stream.

Question 26

Ampiphatic defintion.

Answer 26

A molecule with both hydrophobic and hydrophilic properties.

Question 27

Development of atherosclerosis.

Answer 27

1) Inner wall of artery has smooth endothelium lining.
2) Atheroma deposited on endothlium, reducing available volume for blood flow.
3) Lumen of the artery becomes almost entirely blocked with atheroma.