lipids Flashcards
What is the basic principle behind B oxidation?
A long fatty acid chain ( X C) makes x/2 acCOA, x/2-1 NADH, FADH and H2O
What are lipids? Do they have double bond?
Hydrocarbon chains with a hydrophilic head. Smaller head than phospholipids-usually only 2 O. Eg: palmitic acid 16C and 2O
They can be either saturated or unsaturated, but usually saturated for oxidation
How are lipids stored? In what form? Where?
In the form of triaglycerol, with a glycerol head and 3 fatty acid tails. If saturated, then tightly packed-solid. If unsaturated-bent-liquid
They are usually found in the cytosol of cells-in mammals most adipocytes in adipose tissue
Where do fats come from? How are they absorbed? And transported?
Fats can come from adipose tissue, de novo biosynthesis or diet In the diet, they are absorbed by the small intestine enterocytes Bile salts (one hydrophobic, one hydrophillic side) (stored in gallbladder) help emulsify fats for absorption They are absorbed as free FA (after intestine digestion), remade into TAG, CE and then exported as chylomycrons to liver
What is orlistat?
Potent inhibitor of intestine lipases-reduces fast absorption by 30%
What is the necessary step to prepare for B oxidation? Where does it happen?
Fatty acid is converted to acyl coa specie using HS COA and Atp, making an AMP
This occurs in the OMS
How are acyl COA transported into the IMM?
Carnitine shuttle
Acyl COA cannot pass the IM, so becomes with carnitine, acyl carnitine, releasing a COA
Acyl carnitin is translocated across the membrane, and acyl transferase removes the carnitine and adds the coa back in-remaking acyl coa
What is cycle of B oxidation?
acyl COA is oxidated (release FADH2), then hydrated, oxidised again (release NADH) and thiolysis-realeasing AcCOA, and taking up another HSCOA to repear the cycle (lose 2 C each time)
What are ketone bodies and how are they produced?
Ketone bodies are alternatives og glucose made from fatty acids-when carbohydrate and B oxidation are unbalanced. Make acetoacetate, and then hydroxybutyrate and acetone (acetone evaporates)
What are the enzymes of lipidogenesis?
Fatty acid synthesis if based on 2 enzymes- AcetylCOA decarboxylase and Fatty acid Synthase ( a giant complex using ACP to carry fatty acid around)
What are the main steps of lipidogenesis?
acetylCOA-> malonyl coa (by carboxylation), then link to ACP removing COA. Same is done with another acetyl COA, and the 2 are added together-making acetoacylACP, then reduced and dehydrated and reduced again, making butyryl coa, and reapeating. EAch reduction uses an NADPH
What 2 diseases are caused by lipid porblems
MCADD and Craetine defficiency
