lipids

Question 1

what are some purposes of lipids?

Answer 1

stored form of energy 
structural component of cell membranes
needed as enzyme cofactors
used in hormones 
used for synthesis of vitamins A, D, E and K
used as signalling molecules

Question 2

what is the structure of a fatty acid?

Answer 2

hydrocarbon chains with a carboxylic acid at one end.

Question 3

what are the two forms which a fatty acid can be present in?

Answer 3

saturated or unsaturated

Question 4

what are essential fatty acids?

Answer 4

acids that must be obtained via our diets

Question 5

what are triacylglycerides(TAGs) formed from?

Answer 5

esters of fatty acids and glycerol

Question 6

what are some function of TAGs?

Answer 6

major component of adipose tissue

at as insulation and dietary fuel

Question 7

what is the structure of phospholipids?

Answer 7

glycerol bonded to two fatty acids and a phosphate group

Question 8

phospholipids are amphipathic; true or false?

Answer 8

true

Question 9

where does most digestion of triacylglycerols take place?

Answer 9

small intestine

Question 10

what mechanisms aid the digestion of TAGs in the small intestine?

Answer 10

pancreatic enzymes

emulsification by bile salts and peristalsis

Question 11

what is most TAG digested to?

Answer 11

monoacylglycerol and two fatty acids

Question 12

what are cholesterol esters broken down into?

Answer 12

cholesterol and a fatty acid

Question 13

what are phospholipids broken down into?

Answer 13

hydrolysed to a fatty acid and lysophospholipid

Question 14

what happens to the products of lipid digestion after they are digested?

Answer 14

they form mixed micelles with bile salts

Question 15

what do mixed micelles do when they approach the brush border?

Answer 15

release their contents

Question 16

what types of fatty acids would form mixed micelles?

Answer 16

long chain fatty acids

Question 17

how are lipids transported in the body?

Answer 17

TAG, fatty acids and cholesterol esters are repackaged into chylomicrons, which are released into the blood via the lymphatic system.

Question 18

what happens to chylomicrons when they reach tissues?

Answer 18

TAG is hydrolysed to fatty acids and glycerol by lipoprotein lipase.

Question 19

what is the purpose of the free fatty acids produced from TAG hydrolysation?

Answer 19

used for energy

re-esterified into TAG for storage

Question 20

how are free fatty acids transported?

Answer 20

lipoproteins, in a complex with serum albumin

Question 21

how are fats transported?

Answer 21

high and low density lipoproteins?

Question 22

what is the difference between high density and low density lipoproteins?

Answer 22

low density lipoproteins take cholesterol from the liver to other tissues
high density lipoproteins do the opposite, bring back cholesterol from the tissues to the liver for elimination

Question 23

how many carbons are degraded at a time in beta oxidation?

Answer 23

2

Question 24

what are the products of fatty acid metabolism via beta oxidation?

Answer 24

acetyl CoA
NADH
FADH2

Question 25

what are the 3 stages of beta oxidation?

Answer 25

activation transport degradation

Question 26

what happens in the activation stage?

Answer 26

fatty acids are activated to form fatty acyl CoA in the cytoplasm

Question 27

what happens in the transport stage?

Answer 27

carnitine shuttle transfers long chain fatty acyl CoA from the cytoplasm to the inside of the mitochondrion

Question 28

what inhibits carnitine fatty acyl transferase and why is this significant?

Answer 28

malonyl CoA, which is used in fatty acid synthesis, therefore, synthesis and degradation cannot occur simultaneously

Question 29

what happens in the degradation stage?

Answer 29

fatty acyl coA is dehydrogenated to form FADH2 and another intermediate.

Question 30

what happens to the intermediate that is not FADH2 that is produced in fatty acid degradation?

Answer 30

it is hydrated, then dehydrogenated again to form NADH

Question 31

what is the final step of fatty acid degradation?

Answer 31

thiolysis occurs, to form acetyl CoA that feeds into the CAC

Question 32

what are the products of beta oxidation?

Answer 32

1 acetyl CoA 1 NADH 1 FADH2 carbon species 2 carbons shorter than the original.

Question 33

what happens to acetyl CoA from fat metabolism when it is in excess?

Answer 33

forms ketone bodies

Question 34

what types of tissues can use ketone bodies as fuel sources?

Answer 34

cardiac and skeletal muscle | brain can utilise it in times of starvation

Question 35

where does ketogenesis occur?

Answer 35

liver

Question 36

what are the main ketone bodies?

Answer 36

acetoacetate and 3-hydroxybutarate