Lipids

Question 1

What are the main classes of lipids?

Answer 1

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

Question 2

Explain stage 1 of lipid metabolism

Answer 2

lipids–> FA’s and glycerol by pancreatic lipases

recombine to transported in chylomicrons to consumer tissue and adipose tissue

Question 3

What are FA’s bound to when they travel in the blood to consumer tissue form adipose tissue ?

Answer 3

albumin

Question 4

What enzyme release FA’s from adipose tissue, what hormones are involved?

Answer 4

hormone sensitive lipase
increase activity- glucagon and adrenaline
decrease activity-insulin

Question 5

When FA’s reach consumer tissue what activates them, what enzyme is involved?

Answer 5

cytoplasm linked to co enyzme A by fatty acyl coA synthase

Question 6

What shuttles fatty acyl co A across the mt membrane? What enzymes are involved?

Answer 6

carnitine shuttle transporter

CAT1/2- carnitine acyle transferases

Question 7

What inhibits the carnitine shuttle transporter?

Answer 7

malonyl coA

Question 8

What occurs if there are defects in the carnitine shuttle transporter?

Answer 8

lipid droplets in muscle

exercise intolerance

Question 9

Explain the process of beta oxidation.

Answer 9

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

Question 10

What is the first step in glycerol metabolism and what enzyme is involved?

Answer 10

glycerol to glycerol phosphate by gylcerol kinase

Question 11

What can glycerol phosphate be used for?

Answer 11

TAG synthesis

converted to DHAP which then enters glycolysis

Question 12

What is key about acetyl coA?

Answer 12

main convergence point for catabolic pathways krebs and is used in anabolic pathways –> FA’s, hmg, co2

Question 13

Name the three main ketones

Answer 13

aceto acetate
acetone
beta hydroxybutyrate

Question 14

What is the normal concentration of ketone bodies?

Answer 14

<1mM

Question 15

What is physiological ketosis?

Answer 15

2-10mM ketone conc due to starvation

Question 16

What is pathological ketosis?

Answer 16

> 10mM ketone conc due to untreated t1d

Question 17

What happens if ketone level above renal threshold?

Answer 17

ketouria

Question 18

What is it called when the ketone body level is raised?

Answer 18

ketoacidosis

Question 19

Where are ketone bodies metabolised?

Answer 19

liver mitochondria

Question 20

Explain how ketone bodies are produced from acetyl coA?

Answer 20

acetyl coA + synthase –> HMG-coA

lysase HMGcoA–> ketone bodies

Question 21

What enzyme produces cholestrol form HMG coA?

Answer 21

hmg coa reductase

Question 22

Why does the acetyl coa get diverted from the TCA cycle?

Answer 22

isocitrate and alpha ketoglutarate inhibited by low NAD / nadh product inhibition so it is diverted

Question 23

What pathway is produced in insulin conditions from HMG-CoA?

Answer 23

cholestrol

Question 24

What pathway is activated in glucagon conditions from HMG-CoA?

Answer 24

Ketone bodies

Question 25

Why are ketone bodies produced in starvation?

Answer 25

spare glucose for the brain as they provide muscle with energy