Cholesterol

Question 1

What is cholesterol? How can it be optained

Answer 1

A steroid Fatty acid like structure, with 4 ring and a tail-C27, and a hydrophilic head-can force lipid rafts
Can be taken in in diet or storage or made from acCOA

Question 2

What are key steps in chol biosynthesis? Where does it happen?

Answer 2

3 main parts-synthesis of isopentate pyrophosphate (5C) from Ac COA, then 6 IPP to make 30C squalene, (Ctyoplasm)and finally cyclisation and demthylation to make Cholesterol (in ER

Question 3

What is a key enzyme in chol synthesis?

Answer 3

HMG Reductase is rate limiting-target for drugs-statins. Down regulated chol production, and in turn FA absorption and secretion

Question 4

What is the role of chol in singalling?

Answer 4

Cholesterol can make pregnelone by demolase, which is a precusor to all 5 class of hormones (porgesterone, glucocoirticoids, Mineralcorticoids, Androgens and estrogens)

Question 5

Why do we need vitamin D and sun?

Answer 5

Vit D is made from cholesterol, by using ultraviolet light to catalyse a reaction

Question 6

What is 2 other fate for chol?

Answer 6

Can be used to make bile salts-glycocholate and taurocholate. CAn finally also be used to make hedgehog singals

Question 7

How are Fatty acids transported?

Answer 7

As lipoproteins, formed of a hydrophobic core,a nd hydrophilic center-sourounded by proteins that wrap and help recognise. They are usually composed of FA and CE

Question 8

What are CE and how are they made?

Answer 8

CE are cholesterol ester, made from Chol and choline by LCAT-they are very hydrophobic and pack more into the core-making dense lipoprots

Question 9

What are the different types of lipoproteins and where are they made?

Answer 9

Chylomycrons (by enterocytes), VLDL, IDL, LDL, HDL (LIVER)

Question 10

How are chylomycrons taken up?

Answer 10

After entering bloodstream, endothelial tissue wil have LPL on its surface. ACII on Chyl activates LPL, and then parts of the TAG are removed and taken up-remanents continue in the steam until complete uptake

Question 11

How is LDL uptaken?

Answer 11

LDL is made by the liver and sent to other tissues. LDLR-a EGFR like receptor binds LDL and endocytoses in a vesicle-in lysosome, pH difference make the LDL separate, leaving LDLR to be recycled and LDL to be degraded

Question 12

What is Fh, how many classes of mutation are there and which ones?

Answer 12

Familial hyperchoelstermia-recessive
Class i-synthesis
Class II- transport
Class III-binding
Class IV-vesicle formation
Class V-recylcing/release of LDL

Question 13

What are the treatment options of FH?

Answer 13

Statins and Resons/sequestrants