Lipids

Question 1

3 sources of fats

Answer 1

Diet
De novo biosynthesis
Adipocyte stores

Question 2

Describe the process of lipid digestion

Answer 2

Lipase breaks down triacylglycerols 
Mono, diacylglycerols, fatty acids, bile salt, cholesterol, fat-soluble lipids and lysophosphatidic acid make micelles 
Enter enterocytes
Triacylglycerol reformed 
Modified into chylomicrons
Enter lymphatic system

Question 3

Describe beta oxidation

Answer 3

Fatty acid -> acyl coA using 2 ATPs in outer mitochondrial membrane
Enter mitochondria by carnitine shuttle
Fatty acyl coA:
oxidised to give of FADH2
Hydrolysed
Oxidised to give NADH
CoA comes and takes off 2C —> acetyl coA using B KETOTHIOLASE

Question 4

Overall equation for breakdown of palmitate

Answer 4

Palmitoyl coA + 7FAD + 7 NAD+ + 7H20 + 7CoA ——> 8 acetyl coA + 7 FADH2 + 7 NADH

Question 5

When can acetyl coA from beta oxidation enter TCA?

Answer 5

When beta oxidation and carbohydrate metabolism are balanced as oxaloacetate is needed

Question 6

Which 2 enzymes are involved in biosynthesis of lipids?

Answer 6

Acetyl coA carboxylase

Fatty acid synthase

Question 7

What happens if acetyl coA can’t enter TCA?

Answer 7

Produces:
Acetoacetate
D 3 hydroxybutyrate
Acetone

Question 8

Describe lipogenesis

Answer 8

Acetyl coA + HCO3 = malonyl coA using acetyl coA carboxylase
Transfer malonyl to ACP = malonyl ACP using malonyl-coA-ACP transferase
Transfer acetyl from acetyl coA to ACP = acetyl ACP using acetyl-coA-ACP transferase
Condensation of acetyl ACP and malonyl ACP = acetoacyl ACP
Reduction using ketoreductase
Dehydration using dehydratase
Reduction using Ebola reductase

Question 9

Differences between fat metabolism and synthesis

Answer 9

Synthesis = ACP and uses NADP as reducing agent, happens in ER and mitochondria 
Metabolism = coA and uses NAD+ and FAD as reducing agents , happens in mitochondria

Question 10

Lipogenesis equation

Answer 10

Acetyl coA + 7 malonyl coA + 14 NADP + 14H+ = palmitate + CO2 +6H2O + 8 coA + 14 NADP+

Question 11

Diseases to do with lipid metabolism

Answer 11

Medium chain acyl coA dehydrogenase deficiency (MCADD) 
- autosomal recessive 
- part of heel prick test
-  no fasting
- have a high carb diet 
Primary carnitine deficiency
- autosomal recessive
- carnitine supplements given