Energy Production Lipids Flashcards
What is a lipid?
naturally occurring: fats, waxes, sterols, fat-sol vit = generally hydrophobic,
most only contain C, H, O,
more reduced than carb = releases more energy when oxidised but requires more O2
Describe the classes of lipids
1) Fatty acid derivatives: storage, components of membranes.
2) hydroxyl-methyl-glutaric acid derivative: water soluble, can make ketone bodies = soluble storage.
3) vits: A, D, E, K, have to get in diet
What are the tissues involved in triglyceride metabolism?
G.I. triglyceride –> fatty acids (forms chylomicrons in blood then laid down as adipose tissue – which can be broken down to fatty acids and used for muscle growth) + glycerol (blood transports to liver)
Triglyceride can be broken down to what?
Fatty acids and glycerol
How are dietary fatty acids processed to produce energy?
Stage 1: GI, lipase cleaves fatty acid and glycerol – transported as chylomicrons – stored as adipose or FA oxidation for energy by consumer tissues.
Stage 2: FA activated by linking to CoA, carnitine shuttle into mitochondria – beta-oxidised, C2 removed, reducing equivalents added to NAD+/FAD - forms acetyl-CoA, combine with krebs cycle
How are dietary glycerol’s processed to produce energy?
Glycerol transported to liver – metabolised: glycerol kinase catalyses to glycerol phosphate – which can be used in glycolysis
How many ATP are produced from fat metabolism?
~41
What is the function of acetyl CoA?
Most important intermediate in both catabolic and anabolic pathway: fat synthesis, Co2 release through TCA cycle, ketone body synthesis, cholesterol synthesis
Which ketone bodies are produced in the body?
Acetoacetate, acetone, beta-hydroxybutyrate
Explain how and when ketone bodies are formed and used
Ketone prod raises during starvation or untreated T1 diabetes, synthesised by liver mitochondria, either stored as cholesterol or prod beta-hydroxybutyrate.
Glucose low = release of fatty acids from adipose = prod of acetyl CoA = large prod of NADH which inhibits enzymes in TCA cycle in the LIVER,
acetyl-CoA no longer being used by inhibited LIVER TCA cycle = levels rise = diverted out for ketone prod
ketone bodies go to blood to muscle = reform acetyl-Co A and re-enter MUSCLE TCA cycle
Why ketone bodies are formed?
Ketone bodies can be used to make acetyl CoA – conserving the low glucose for use by the brain
How do statins work?
Inhibit HMG-CoA reductase which converts ketone bodies into cholesterol to be stored
Name the mechanism by which activated fatty acids enter mitochondria
Carnitine shuttle
In fatty acid catabolism, which enzyme activates fatty acids by linking CoA?
Fatty acyl CoA synthase
What inhibits the carnitine shuttle?
Malonyl-CoA
