Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

MTC > carbohydrate metabolism > Flashcards

carbohydrate metabolism Flashcards

wk 8

1
Q

how is excess glucose stored?

A

as Glycogen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

where are glycogen granules?

A

in the liver and skeletal muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How much of liver content is glycogen in a well-fed state?

A

8%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is glycogen synthesis catalysed by?

A

Glycogen synthase and a branching enzyme

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the three parts of Glycogen synthesis?

A
  1. Glucose 6 phosphate
  2. UDP-Glucose synthesised from G1P
  3. Glycogen synthesis catalysed by Glycogen synthase and a branching enzyme
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are the two parts of Glycogen Degradation?

A
  1. Catalysed by glycogen phosphorylase and debrancher enzyme.
  2. Glucose 6 Phosphate in liver generates free glucose from glucose 6-phosphate.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How much ATP is used to create glycogen?

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the three steps of glycogen sythesis?

A

Phosphoglucomutase transforms G6P –> G1P

G1P reacts with Uridine-5’-triphosphate

Addition of UDP onto glycogen chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what is the Delta G of Glycogen Synthesis?

A

-33.4 KJ/mol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the three steps of glycogen degradation (glyconeolysis)

A

Glycogen phosphorylase cleaves off a glucose molecule one at time

Conserves energy of the glycosidic bond by adding Phosphate to form Glucose 1-P

G1P converted to G6P using phosphoglucomutase and G6P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What enzyme is used to convert G1P into G6P?

A

Phoosphoglucomutase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What enzyme is used to convert G6P into G1P?

A

Phosphoglucomutase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is glucose levels mechanistically regulated?

A

via the phosphorylation of glycogen synthase and glycogen phosphorylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the role of liver with glycogen?

A

Makes glycogen after carbohydrate meal and degrades it during fasting.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What do skeletal muscles do with Glycogen?

A

Skeletal muscles: synthesis glycogen at rest and degrade it during exercise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

How does Skeletal muscle metabolise glucose-6-phosphate if it has no glucose-6-phosphatase?

A

via glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does PP reduce for each G6P oxidatively decarbonised?

A

two molecules of NADPH from NADP+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What does PPP produce?

A

ribose-5-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is NADPH?

A

primary reductant in the cell

critical for mainatining reduced glutathione levels in cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is NAD+

A

primary oxidant

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is generated in the oxidative phase of PPP and why?

A

NADPH for biosynthetic pathways and detoxification of reactive O species

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What occurs in the non-oxidative phases of PPP and why?

A

Interconverts C3-7 monosaccharides to produce ribose-5P for nucleotide synthesis.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the net reaction of PPP and its equation?

A

to generate maximum amount of NADPH

G6P + 2NADP+ –> Ribose-5-P + 2 NADPH2 + Co2

24
Q

What are the three reactions of PPP?

A

G6P oxidised to produce 6-phospho-glucono-delta-lactone and reduces NADP+ –> NADPH2

Hydration reaction: addition of water: 6-phosphogluconolactonase forms 6-Phosphogluconate

6-phosphategluconate dehydrogenase: 6-phosphgluconate is decarboxylated (loses CO2) and reduces NADP+ –> NADPH2 to form ribose-5-P

25
Q

in-terms of regulating PPP, what does Insulin promote?

A

G6P dehydrogenase and 6-phosphogluconate dehydrogenase activity

26
Q

What is G6P dehydrogenas inhibited by?

A

high [NADPH]:[NADP+] ratio

27
Q

What diseases are ROS associated wth?

A

atherosclerosis, diabetes, cancer, neurodegeneration and aging

28
Q

How does NADPh protect cells from oxidative damage?

A

by maintaining reduced glutathione

29
Q

what is glutathione?

A

Tripeptide with glutamate, Cycteine and glycine.

30
Q

What is the functional group of glutathione?

A

cystenine

31
Q

What are the two main reasons our livers undergo gluconeogenesis?

A

To maintain blood glucose and provide glucose from non-carbohydrate precursors

To use other biosynthetic precursors so that cells can make ribose.

32
Q

what are other carbon sources?

A

amino acids, glycerol (from fats) and lactate

33
Q

simply, how does gluconeogenesis differ from glycolysis?

A

Are opposing pathways

NOT the reverse of glycolysis

3 kinase catalysed reactions” Hexokinase, PFK1 and Pyruvate Kinase

Replaced by 4 gluconeogenic enzymes

34
Q

Where does gluconeogenesis occur?

A

liver and the proximal convoluted tubules of the kidney

35
Q

Why does gluconeogenesis occur?

A

If blood glucose levels are low (hypoglycaemia)
and for brain function

36
Q

Why does gluconeogenesis require different enzymes than glycolysis?

A

because some steps of glycolysis are irreversible so it needs to use different processes.

37
Q

What does pyruvate do first to begin glconeogenesis?

A

Enters the mitochondria, joins the TCA cycle and is converted into OAA

38
Q

What enzyme concerts Acetylate into OAA?

A

pyruvate carboxylase

39
Q

Why is OAA converted into malate in gluconeogenesis?

A

because OAA cant get out of the mitochondrial membrane but Malate can.

40
Q

What enzyme converts OAA into PEP? And what does this enzyme do?

A

PEPCK

removes CO2 and adds a P

41
Q

What enzyme allows f1,6BP to be converted into G6P? What does it do?

A

Fructose 1,6 Bisphosphoatase

Removes P from 1C

42
Q

Where does G6P go to become glucose?

A

SER

43
Q

Is more glycogen storage more in liver or muscles?

A

muscles= 1% but is 400g

44
Q

which one is a 1 enzyme pathway?

A

glycogenolysis (breakdown)

45
Q

what enzyme does glycogenolysis have?

A

glycogen phosphorylase

46
Q

what occurs in glycogenolysis?

A

cosnevres enegy of glycosidic bonds: adds phosphate to G-1-P then convers it to G6P

47
Q

what does Insulin turn on?

A

Glycogen synthase using protein phosphatase in which it removes P to make glycogen

48
Q

What does insulin turn off?

A

Glycogen phosphorylase - via inhibition of protein phosphatase.

49
Q

what is NADPH critical for?

A

getting rid of Reactive oxygen species by maintaining reduced glutathione

50
Q

What is the NADPH from PPP used for?

A

Fatty acid synthesis, glutathione reduction and other reactions (detoxification)

51
Q

Are the three reactions of PPP irreversible or reversible?

A

irreversible

52
Q

what are some examples of ROS?

A

Oxyegn, superoxide anion, peroxide, hydrogen peroxide, hydroxyl radical and hydroxyl ion

53
Q

how are ROC’s created?

A

electrons escape from the ECT and bind to O.

54
Q

What is the purpose of the Cori cycle?

A

mechnaism that converts lactate (produced via anaerobic glycolysis) to glucose using gluconeogenic pathway

55
Q

What is the cost of the Cori Cycle?

A

4 ATP equivalents

56
Q

Where is the NADH2 used in the ETC from?

A

produced in the mitochondrial matrix by the bridging reaction and TCA cycle.

MTC (14 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions