lipids 3

Question 1

what are fatty acid syntheses from and where does it take place?

Answer 1

fatty acids are formed from acetyl CoA and the reaction takes place in the cytosol of the liver, lactating mammary gland and adipose tissue)

Question 2

what transports the acetyl CoA from the mitochondria to the cytosol

Answer 2

citrate shuttle

Question 3

cholesterol:

functions

Answer 3

used as chemical messengers.
used for structure in cell membranes -lipoproteins
precursor for bile acids, steroids, vitamin D.

Question 4

eicosanoids:
functions
where are they derived from

Answer 4

-precursor to prostaglandins-pain
-thromboxanes-blood clotting
-leukotrienes-vasoconstriction
control over inflammation
control over immunity
control over sleep cycle.
derived from:
omega-3 and omega-6 which give rise to arachidonic acid

Question 5

statins

Answer 5

in formation of cholesterol from FAs, the rate determining step is defined by HMG-CoA. if this is limited then cholesterol cannot be synthesised.
-Statin inhibit HMG-CoA reductase.

Question 6

from Acetyl CoA to palmitic acid

Answer 6

1- acetyl CoA is found in the mitochondrial matrix. it is transported out of here as citrate as all the enzymes required are found in the cytoplasm.
2-In the cytoplasm citrate is broken back down into Acetyl CoA.
3- acetyl CoA is converted into malonyl-CoA through hydrolysis of ATP.
4- malonyl CoA is converted into palmityl-ACP through 2 NADPH and loss of H20 and CO2.– reduction, hydration, reduction
5- the Palmityl is then cleaved from the Palmityl-ACP using a theoesterase.

Question 7

what is the rate determining step of this reaction?

how is it controlled?

Answer 7

Acetyl Coa to Malonyl CoA.
controlled allosterically and hormonally.
Allosterically : citrate
Hormonally: insulin and glugacon.