Lipid Biosynthesis

Question 0

Coenzyme of fatty acid synthesis

Answer 0

NADP+/NADPH

Question 1

Location of fatty acid synthesis

Answer 1

Cytosol

Question 2

Steps of fatty acid synthesis

Answer 2

1: constructed from 2 carbon units- acetyl-CoA
2: acetyl-CoA activated by CO2 to form malonyl-CoA, requires ATP (rate determining step)
3: decarboxylation of each 2 carbon addition

Question 3

NADPH precursor location

Answer 3

8 come from malate oxidation

6 come from pentose phosphate pathway

Question 4

Citrate/malate/pyruvate shuttle purpose

Answer 4

Transport citrate out of the mitochondria to produce oxaloacetate and acetyl-CoA
OOA is reduced to malate which is shuttled back into the mitochondria
Malate is then oxidatively decarboxylated to pyruvate

Question 5

Enzyme of malonyl-CoA production

Answer 5

Acetyl-CoA carboxylase

Question 6

Subunits of acetyl-CoA carboxylase

Answer 6

Biotin carboxyl carrier protein, biotin carboxylase, transcarboxylase

Question 7

Coupling of fatty acid oxidation and synthesis

Answer 7

Malonyl-CoA inhibits uptake of fatty acylcarnitine by mitochondria
High fatty acyl-CoA levels then fatty acid synthesis is limited and fatty acid oxidation is increased

Question 8

Cholesterol biosynthesis

Answer 8

Happens in the liver

Begins in the cytosol with synthesis of mevalonate from acetyl-CoA

Question 9

Steps forming mevalonate

Answer 9

(First committed step of cholesterol synthesis)

1: claisen condensation of 2 acetyl-CoA molecules catalyzed by 3-ketothiolase
2: acetyl-CoA and acetoactyl-CoA join to form 3-hydroxy 3-methyl glutaryl CoA (HMG-CoA), done by HMG-CoA synthase
3: HMG-CoA reductase makes 3R-mevalonate in 2 NADPH dependent reductions

Question 10

Beta-oxidation inhibited

Answer 10

Malonyl-CoA blocks carnitine acyltransferase

Question 11

Acetyl-CoA carboxylase activated

Answer 11

Citrate