FA's Synthesis

Question 1

What are the 4 functions of lipids?

Answer 1

fuel storage
structural components
cell signaling
other (insulation, generation of heat)

Question 2

How much would a man weight if TAG was changed to Gylcogen?

Answer 2

70kg man weight 134kg (6.75 more energy for fats)

Question 3

FA synthesis occurs primarily in what organ?

Other organs also carry out process?

Answer 3

Liver

Also adipose tissue, kidney, brain, lactatiting mammary gland

Question 4

What is the first enzyme in FA synehtesis? What RXn catalyze?

Answer 4

Citrate synthase First step in CAC

Shuttle out Citrate into cytoplasm

Question 5

Positive and Negative Regulations of

ATP Citrate synthesis?

Answer 5

+: Glucose, insulin induce gene expression
Phosphorylation of enzyme
-: PUFA (Polyunsaturated Fatty Acid), leptin

Question 6

What is the rate limiting step of FA synthesis?

What is used as a cofactor for this enzyme?

Answer 6

Conversion of acetyl CoA to malonyl CoA by Acetyl CoA Carboxylase also uses CO2 and ATP
Cofactor: Biotin (B7)

Question 7

Positive and Negative Regulations for Acetyl CoA Carbozylase (ACC)?

Answer 7

allosteric binding + citrate ; - Palmate (long chain FA)
Phosphorylation (-)/Dephosphorylation (+)
• Insulin (+) via activation of protein phosphatase
• Epinephrine (-) via activation of protein kinase A
• Glucagon (-) via activation of protein kinase A
• AMP (-) via activation of AMP kinase (energy sensor) Induction/repression
• Gene expression up-regulated by high carb/low fat diet

Question 8

What does Malonyl CoA do for degradation of FA?

Answer 8

Works as an inhibitor for carnitine acetyltransferase used for FA degradation so do not occur similtaneously

Question 9

Fatty Acid Sythase is made up of?

Answer 9

2 dimers arranged head to tail with 7 enzyme activities and Acyl carrier protein

Question 10

How is the Fatty Acid Synthetase regulated?

Answer 10

• Allosteric effect (presence of phosphorylated
sugars) – increase activity
• Induction and repression at gene level
– Insulin and glucocorticoid hormones increase
synthesis
– High carb/low fat diets increase synthesis.
– High fat diets as well as starvation lowers synthesis.
– High PUFA suppresses synthesis

Question 11

What did Leptin Show us?

Answer 11

Leptin hormone secreted by adipose tissue (in proportion) and regulated body weight by inhibiting food intake, stimulating energy expenditure
binds in hupothalamus to receptor

Question 12

Where can palmate be enlogated?

What are the two carbon donators?

Answer 12

SER and Mitocondria

SER uses Malonyl CoA and Mitocondria Acetyl Co A

Question 13

What enzyme is used as a desaturase? Where can they desaturate on the molecule?

Answer 13

Aceyl Co A desaturases

4, 5, 6, 9 only all other require essential FA’s

Question 14

What are the homones that regulate the desaturase?

Answer 14

Insulin induce and Polyunsaturated FA will suppress

Cholesterol induces Delta 9, suppresses others

Question 15

What are the Essential FA’s? What can they make?

Answer 15

Lenoleic, Lenolenic Acids are Essential
Lenoleic used to make arachadonic acid
Lenolenic used to make eicosapentanoic acid (EPA) (20:5 ω3) and docosahexanoic acid (DHA) (22:6 ω3)