Metabolic Biochemistry Flashcards
What is the role of cholesterol in the plasma membrane? (9)
- Component of membranes
- Regulates fluidity
slide 4
What is cholesterol? (9)
- Precursor of steroid hormone
(such as progesterone, testosterone, oestradiol, hydrocortisone (cortisol) and vitamin D
Slide 5
Where is cholesterol found? (9)
Carried in plasma in lipoproteins
Slide 5
Where does Cholesterol synthesis take place? (9)
In the liver and small intestine
Slide 8
Slide 9 - Cholesterol synthesis -
Acetly CoA + acetoacetyl CoA
——>
(9)
3-hydroxy-3-methylglutaryl CoA
Cholesterol synthesis :
3-hydroxy-3methylglutaryl CoA
——->
(9)
Mevalonate
(slide 9)
Cholesterol synthesis : Mevalonate ——>
(9)
Squalene
(slide 9)
Cholesterol synthesis: Squalene ——->
(9)
Cholesterol
slide 9
Outline the entire cholesterol synthesis steps (9)
acetyl CoA + acetoacetyl CoA
——->
3-hydroxy-3-methylglutaryl CoA
—–>
mevalonate
——–>
squalene
———>
cholesterol
Slide 9
Synthesis of 3-hydroxy-3-methylglutaryl CoA (9) (HMG CoA)
Acetyl CoA + Acetoacetyl CoA ——–> 3-hydroxy-3-methylglutaryl CoA
Slide 10
What is the rate controlling step between HMG CoA to mevalonate? (9)
3-Hydroxy-3-methylglutaryl CoA reductase
slide 11
Control of HMG CoA reductase: Describe how mRNA synthesis is inhibited. (9)
Cholesterol inhibits the translation of mRNA and stimulate enzyme degradation as a long term control
Phosphorylation to AMP - activated protein kinase inhibits acutely
**Inhibited by drugs (statins)
slide 12
How are Cholesterol transported?
(9)
Cholesterol and triacylglycerol is readily soluble in plasma
Transported in lipoproteins
Slide 13
Major lipoproteins: Dietary triacylglycerol? (9)
Chylomicrons
Slide 15
Major lipoproteins: Endogenous triacylglycerol? (9)
Very low density lipoprotein (VLDL)
slide 15
Major lipoproteins: Cholesteryl ester? (9)
Intermediate density lipoprotein
(IDL)
Slide 15
Major Lipoprotein: Cholesteryl ester? (9)
Low density lipoprotein (LDL)
Slide 15
Major Lipoprotein: Phospholipid/cholesteryl ester? (9)
High density lipoprotein (HDL)
Slide 15
HDL versus Chylomicrons - Protein is denser than lipid (9)
e.g. chylomicrons are 2% protein/98% lipid by weight
and have density of <0.95 g/ml
HDL is 55% protein/45% lipid
and has density 1.063-1.21 g/ml
Chylomirons have a mean
diameter of 400 nm
HDL is about 10 nm
Slide 16
What is Lipoprotein Lipase? (9)
Enzyme bound to lumenal surface of endothelial cells in capillaries mainly in skeletal muscle, adipose tissue and heart
Slide 21
