Cholesterol Flashcards
Acetyl-CoA can lead to HMG-CoA which can lead to:
Ketone bodies
Cholesterol (then steroids)
What are some key features of cholesterol?
Rigid, hydrophobic, 4 rings
Enriched in plasma membranes of eukaryotes
Required for eukaryotic growth
Absent in prokaryotes
How is cholesterol important for membranes?
Modulates physical properties
Controls fluidity and curvature
Maintains integrity - prevents leaks
Cholesterol is a precursor to:
Bile salts (detergents- dietary fat absorption, more polar) Steroid hormones (androgens, estrogens, adrenal) Vitamin D3
How is cholesterol homeostasis maintained?
We lose the same amount of cholesterol (via bile salts and free cholesterol) each day as is made or ingested. (We make more than we eat)
How is cholesterol related to atherosclerosis?
Correlation
Narrowing and hardening of the arteries due to plaque - aggregate of cholesterol, fat, calcium, fibrin
Inflammatory
Many complicated biomolecules are made from ____________. List properties of these.
Isoprenoids (isoprene lipids) 5 C Steroids, cholesterol Essentail oils Natural antibiotics, antifungals Pheromones Carotenoids Drugs (taxol)
What is the basic process of isoprenoid biosynthesis to cholesterol?
C5 building block from acetyl-CoA (mevalonate pathway)
Joined to make a chain (Squalene)
Cyclization
Ring structures are decorated
What sources provide Acetyl-CoA for cholesterol biosynthesis?
Glycolysis, PDH
Fatty acid oxidation
Amino acid oxidation
Ethanol
________ is the branch point at the mevalonate pathway that determines that cholesterol will be made instead of ketones. This key regulatory step for cholesterol synthesis (dedicated pathway after this point).
HMG-CoA Reductase
Geranyl and faresyl are ________ precursors that are used to tether proteins to membrane.
Squalene
Storage and transport form of cholesterol
Cholesteryl ester
Water soluble transport lipids with phospholipid exterior, cholesterol and fatty acid interior, and proteins for regulation
Lipoproteins
Least dense (biggest, most fatty) lipoprotein. Moves dietary fat from GI to liver/body
Chylomicron
Moves fats (not just cholesterol) from liver to body
Very low density lipoprotein (VLDL)