Lipids Flashcards
What are the main classes of lipids?
fatty acid derivatives- fa’s, glycogen, pl’s and eicosanoids
Hydroxy-methyl-glutaric acid derivatives- ketone bodies, chol, chol ester, bile acids and salts
vitamins- adek
Explain stage 1 of lipid metabolism
lipids–> FA’s and glycerol by pancreatic lipases
recombine to transported in chylomicrons to consumer tissue and adipose tissue
What are FA’s bound to when they travel in the blood to consumer tissue form adipose tissue ?
albumin
What enzyme release FA’s from adipose tissue, what hormones are involved?
hormone sensitive lipase
increase activity- glucagon and adrenaline
decrease activity-insulin
When FA’s reach consumer tissue what activates them, what enzyme is involved?
cytoplasm linked to co enyzme A by fatty acyl coA synthase
What shuttles fatty acyl co A across the mt membrane? What enzymes are involved?
carnitine shuttle transporter
CAT1/2- carnitine acyle transferases
What inhibits the carnitine shuttle transporter?
malonyl coA
What occurs if there are defects in the carnitine shuttle transporter?
lipid droplets in muscle
exercise intolerance
Explain the process of beta oxidation.
2C lost from FA each cycle repeats until FA used
1 FADH2 per cycle
1 NADH per cycle
NEEDS OXYGEN
need coA as acetyl coA produced for krebs cycle
no ATP synthesis
What is the first step in glycerol metabolism and what enzyme is involved?
glycerol to glycerol phosphate by gylcerol kinase
What can glycerol phosphate be used for?
TAG synthesis
converted to DHAP which then enters glycolysis
What is key about acetyl coA?
main convergence point for catabolic pathways krebs and is used in anabolic pathways –> FA’s, hmg, co2
Name the three main ketones
aceto acetate
acetone
beta hydroxybutyrate
What is the normal concentration of ketone bodies?
<1mM
What is physiological ketosis?
2-10mM ketone conc due to starvation
What is pathological ketosis?
> 10mM ketone conc due to untreated t1d
What happens if ketone level above renal threshold?
ketouria
What is it called when the ketone body level is raised?
ketoacidosis
Where are ketone bodies metabolised?
liver mitochondria
Explain how ketone bodies are produced from acetyl coA?
acetyl coA + synthase –> HMG-coA
lysase HMGcoA–> ketone bodies
What enzyme produces cholestrol form HMG coA?
hmg coa reductase
Why does the acetyl coa get diverted from the TCA cycle?
isocitrate and alpha ketoglutarate inhibited by low NAD / nadh product inhibition so it is diverted
What pathway is produced in insulin conditions from HMG-CoA?
cholestrol
What pathway is activated in glucagon conditions from HMG-CoA?
Ketone bodies
Why are ketone bodies produced in starvation?
spare glucose for the brain as they provide muscle with energy
