Ch. 29 Lipid Synthesis

Question 1

What is the precursor for synthesis of storage and membrane lipids?

Answer 1

Phosphatidate

Question 2

What organ synthesizes triaglycerols?

Answer 2

ER membrane of liver and fat cells

Question 3

How are phosphatidates activated?

Answer 3

CDP, allows interaction with alcohols

Question 4

What are the three stages of cholesterol synthesis from acetyl CoA?

Answer 4

1. Isoprene formed from mevalonate activated bt ATP to form isopentenyl pyrophosphate- occurs in cytoplasm
2. 6 Isopentyl pyrophosphate condense to from squalene- occurs in ER
3. Squalene cyclizes, converted into cholesterol- occurs in ER

Question 5

What is the commited step of Cholesterol synthesis?

Answer 5

Mevalonate is synthesized by HMG CoA reductase

Question 6

What are the 4 regulatory modes of cholesterol synthesis?

Answer 6

Transcriptional
Translational
Degradation
Phosphorylation

Question 7

What is the transcriptional control of cholesterol synthesis?

Answer 7

When SREBP is bound, transcription of HMG-CoA reductase mRNA is increased

Question 8

What is the translational control of cholesterol synthesis?

Answer 8

Metabolites of mevalonate and dietary cholesterol degrade mRNA

Question 9

What is the degradational control of cholesterol synthesis?

Answer 9

High cholesterol drives degradation of HMG-CoA reductase protein

Question 10

What is the phosphorylation control of cholesterol synthesis?

Answer 10

Phosphorylation by AMP-dependant kinase inactivates reductase

Question 11

How is cholesterol transported throughout the body?

Answer 11

Lipoprotein vesicle forms around cholesterol for aqueous transport

Question 12

What is the clinical significance of absence of LDL receptors?

Answer 12

Excess cholesterol ingested by macrophages
Macrophages form plaques in blood vessels

Question 13

What is a therapeutic treatment for high cholesterol?

Answer 13

Inhibitor of LDL recycling blocker