Biochemistry

Question 1

what is glycogenesis

Answer 1

synthesis of glycogen from glucose

Question 2

what is glycogenolysis

Answer 2

breakdown of glycogen to form glucose

Question 3

what is gluconeogenesis

Answer 3

synthesis of glucose from metabolic precursors

Question 4

when would gluconeogenesis be raised?

Answer 4

overnight

Question 5

when would glycogenolysis be raised

Answer 5

in between meals

Question 6

what is glycogen

Answer 6

storage form of glucose

Question 7

function of liver glycogen

Answer 7

maintaining blood glucose

Question 8

function of skeletal muscle glycogen

Answer 8

bursts of energy, not blood glucose

Question 9

what links keep glucose residues together in glycogen

Answer 9

alpha 1-4 glycosidic links

Question 10

what links keep glycogen branches together

Answer 10

1-6 glycosidic links

Question 11

what breaks gucose down into glucose-6-phosphate

Answer 11

hexokinase

Question 12

what is the primer for glycogen

Answer 12

glycogenin, covalently attached to 4 glucose residues

Question 13

what enzyme converts glucose 6-phosphate to glucose-1-phosphate

Answer 13

phosphoglucomutase

Question 14

Addition of UTP to G-1-P is catalysed by _____

Answer 14

UDP-glucose pyrophosphorylase

Question 15

what enzyme adds glucose residues to glycogen

Answer 15

glycogen synthase

Question 16

can glycogen synthase create new glycogen molecules

Answer 16

no, it can only add glucose to existing ones

Question 17

what enzyme is needed to add glucose to a branch of glycogen

Answer 17

transglycolase

Question 18

what enzyme catalyses glycogenolysis

Answer 18

glycogen phosphorylase

Question 19

true/false - in the liver G-6-P can be dephosphorylated to go back to glucose

Answer 19

true

Question 20

true/false - in skeletal muscle G-6-P can be dephosphorylated to go back to glucose

Answer 20

false - it must be broken down via glycolysis and TCA

Question 21

where does gluconeogenesis occur in the body

Answer 21

liver

Question 22

is gluconeogenesis the reverse of glycolysis

Answer 22

no!

Question 23

what enzyme catalyses synthesis of oxaloacetate from metabolites in gluconeogenesis

Answer 23

pyruvate carboxylase

Question 24

what enzyme bypasses pyruvate kinase

Answer 24

PEP carboxylkinase

Question 25

what enzyme bypasses phosphofructokinase

Answer 25

fructose-1,6-bisphosphatase

Question 26

what enzyme bypasses hexokinase to synthesise glucose in gluconeogenesis

Answer 26

glucose-6-phosphatase

Question 27

how much energy does gluconeogenesis use

Answer 27

4ATP | 2GTP

Question 28

where do amino acids participate for use in gluconeogenesis

Answer 28

enter TCA to be converted to oxaloacetate

Question 29

what is the cori cycle

Answer 29

recovery of lactate to pyruvate, to glucose via gluconeogenesis

Question 30

true/false - insulin promotes glycogenesis and glycolysis

Answer 30

true

Question 31

glucagon increases gluconeogenesis by inhibiting ____ and promotoing ____

Answer 31

phosphofructokinase | fructose-1,6-biphosphatase

Question 32

what are TAGs made of and where are they stored

Answer 32

glycerol and 3 fatty acid chains | adipose

Question 33

true/false - fatty acids are usually in trans configuration

Answer 33

false - usually in cis

Question 34

what causes the kink in fatty acid chains

Answer 34

the double bond

Question 35

in order for fats to be absorbed into intestinal mucosa cells, they are broken down into ____, ____ or ____

Answer 35

glycerol fatty acids monoglycerides

Question 36

what is lipolysis and what is it catalysed by

Answer 36

breakdown of lipids, catalysed by hormone sensitive lipases

Question 37

before a fatty acid can be oxidised what must it be converted to?

Answer 37

CoA derivative

Question 38

is fatty acid oxidation a passive process?

Answer 38

no, it requires energy

Question 39

what is the carnitine shuttle

Answer 39

carnitine is acylated by acyl-CoA and travels across mitochondria to acylate another CoA to 'shuttle' across mitochondria

Question 40

products of beta oxidation

Answer 40

1FADH 1NADH+H 1 acyl CoA, 2 carbons shorter 1 Acetyl CoA

Question 41

describe the breakdown of glycerol

Answer 41

glycerol kinase converts it to glycerol-3-phosphate | dehydrogenated to dihydroxyacetone phosphate

Question 42

where are ketone bodies formed

Answer 42

liver mitochondria

Question 43

when may ketones be dangerous

Answer 43

in diabetics as they may develop diabetic ketoacidosis due to the inability to produce insulin

Question 44

where does fatty acid synthesis occur

Answer 44

liver, kidney, adipose, brain

Question 45

excess carbohydrate intake causes it to be....

Answer 45

converted to TAGs and fatty acids

Question 46

what is required for triglyceride synthesis

Answer 46

Glucose 3 phosphate, yielded from glycerol or glucose in the fed state

Question 47

what stimulates triglyceride synthesis

Answer 47

insulin in the fed state

Question 48

the first step of fatty acid synthesis requires acetyl CoA. what produces it

Answer 48

pyruvate dehydrogenase

Question 49

how does Acetyl-CoA enter the cytoplasm from the mitochondria

Answer 49

condenses with oxaloacetate to form citrate to transport to cytoplasm

Question 50

acetyl-CoA carboxylase converts...

Answer 50

acetyl-CoA to manonyl-CoA

Question 51

structure and function of fatty acid synthase

Answer 51

7 functions and an acyl carrier protein | catalyses synthesis f saturated long chain fatty acids from manonyl-CoA, Acetyl-CoA and NADPH

Question 52

how many carbons are added to the growing fatty acid chain by fatty acid synthase per cycle

Answer 52

2

Question 53

what stimulates fatty acid synthesis

Answer 53

insulin | citrate

Question 54

what opposes fatty acid storage

Answer 54

glucagon | adrenaline

Question 55

main site for amino acid degradation

Answer 55

liver

Question 56

what is protein turnover

Answer 56

removal of damaged proteins

Question 57

describe amino acid absorption

Answer 57

proteolytic enzymes yield amino acids, absorbed by enterocytes that are released into the blood

Question 58

what toxic chemicals are released by amino acids and how are they safely excreted

Answer 58

ammonia/ammonium | excretion by urea, uric acid and creatinine

Question 59

aminotransferases turn amino acids to ____

Answer 59

glutamic acid

Question 60

why does glutamic acid get de-aminated

Answer 60

to yield ammonium

Question 61

describe the ornithine cycle

Answer 61

carbamoyl phosphate combines with ornithine and aspartic acid added. coverted to urea and ornithine is reused

Question 62

what happens to the de-aminated carbon skeletons after the ornithine cycle

Answer 62

ketogenic bodies may become ketone bodies or fatty acids | glucogenic bodies may used to produce glucose