Biochemistry

Question 1

glycogenesis

Answer 1

synthesis of glycogen from glucose

Question 2

glycogenolysis

Answer 2

breakdown of glycogen to form glucose

Question 3

gluconeogenesis

Answer 3

de novo synthesis of glucose from metabolic precursors such as lactate, amino acids and glycerol

Question 4

role of glycogen synthase

Answer 4

adds one glucose molecule to a glycogen at a time (cannot introduce branches)

Question 5

role of transglycosylase

Answer 5

produces branches in glycogen

Question 6

which hormone enhances glycogen synthase

Answer 6

insulin

Question 7

which hormone inhibits glycogen synthase

Answer 7

glucagon

Question 8

which enzyme catalyses glycogenolysis

Answer 8

glycogen phosphorylase

Question 9

what enhances the action of glycogen phosphorylase

Answer 9

glucagon, adrenaline and cortisol

Question 10

what inhibits glycogen phosphorylase

Answer 10

insulin

Question 11

what is used to convert lactate to glucose that is released into the blood?

Answer 11

cori cycle

Question 12

two places of glycogen storage

Answer 12

liver

muscle

Question 13

how are amino acids produced in gluconeogensis

Answer 13

proteolysis

Question 14

how is glycerol produced in gluconeogenesis

Answer 14

lipolysis

Question 15

what happens in glycogen storage disease

Answer 15

increased glycogen deposition in liver or muscle or both.

Question 16

what is lipid catabolism

Answer 16

breakdown of lipids

Question 17

what is the main energy storage form in adipose tissue?

Answer 17

TAGs

Question 18

what do TAGs consist of?

Answer 18

glycerol and three fatty acids

Question 19

what are chylomicrons cleaved by?

Answer 19

lipoprotein lipases at muscle and adipose tissue

Question 20

what happens to free fatty acids once they have been cleaved?

Answer 20

• resynthesises to TAGs OR

- oxidised for energy

Question 21

what do free fatty acids have to be converted to so they can be oxidised for energy

Answer 21

CoA-derivatives called acyl-CoA

Question 22

what transports acyl-CoA into the mitochondria from the cytoplasm in lipid breakdown

Answer 22

acyl-carnitine transporter

Question 23

what happens to acyl-CoA once they reach the mitochondria in lipid breakdown

Answer 23

they undergo beta-oxidation

Question 24

which enzyme activates glycerol to glycerol-3-phosphate

Answer 24

glycerol kinase

Question 25

where are ketone bodies formed?

Answer 25

mitochondria from acyl-CoA

Question 26

what is dangerous about ketone bodies

Answer 26

they can diffuse from the liver mitochondria into the blood and accumulate causing acidosis

Question 27

how is ketonic acidosis detected?

Answer 27

acetone on breath

Question 28

what is lipid anabolism

Answer 28

synthesis of fatty acids from acetyl-CoA

Question 29

where does synthesis of fatty acids occur?

Answer 29

cytoplasm of the liver

Question 30

how does acetyl-CoA groups reach the cytoplasm for fatty acid synthesis

Answer 30

citrate

Question 31

what converts acetyl-CoA to malonyl-CoA

Answer 31

acetyl-CoA carboxylase

Question 32

role of fatty acid synthase

Answer 32

catalyses synthesis of long chain fatty acids from malonyl-CoA, acetyl-CoA and NADPH

Question 33

what increases the action of acetyl-CoA carboxylase

Answer 33

citrate | insulin

Question 34

what inhibits the action of acetyl-CoA carboxylase

Answer 34

palmitoyl-CoA AMP glucagon epinephrine

Question 35

synthesis of TAGs

Answer 35

glycerol-3-phosphate and esterification

Question 36

is there a storage form of amino acids?

Answer 36

no

Question 37

what does amino acid breakdown produce

Answer 37

NH3 | NH4+

Question 38

what is amino acid breakdown products secreted as

Answer 38

urea uric acid creatinine NH4+

Question 39

three stages in the synthesis of urea

Answer 39

1. transamination 2. de-amination 3. urea cycle

Question 40

transamination

Answer 40

aminotransferases move amino group from amino acid to ketone acids. alanine and glutamine transfer nitrogen in the blood to the liver

Question 41

de-amination

Answer 41

occurs in the liver, amino group is converted to NH4+

Question 42

define carbon skeletons

Answer 42

amino acids with the alpha amino group removed

Question 43

ketogenic amino acids

Answer 43

degraded to acetyl-CoA which can give rise to ketone bodies and fatty acids

Question 44

glucogenic amino acids

Answer 44

degraded to pyruvate or TCA then glucose

Question 45

inherited disorders of amino acid degradation

Answer 45

- alkaptonuria - maple syrup urine disease - phenyloketonuria