Brainscape's Knowledge GenomeTM

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


See full index

APO510 - MEDICAL BIOCHEMISTRY > WEEK 1: Glycolysis and pyruvate dehydrogenase complex > Flashcards

WEEK 1: Glycolysis and pyruvate dehydrogenase complex Flashcards

You may prefer our related Brainscape-certified flashcards:
USMLE® Step 1 flashcards
1
Q

what is cellular respiration?

A

the oxidation of glucose to form ATP

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

what is glycolysis?

A

first step of cellular respiration that is the breakdown of sugar.
Glucose —> Pyruvate
one 6-carbon molecule of glucose into two 3-carbon molecules of pyruvate

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

why is glycolysis significant? (5)

A
  • principal route for glucose and other hexose metabolism
  • it is the only pathway that takes place in all cells of the body
  • it is the only energy source for erythrocytes
  • it provides carbon skeletons for synthesis of non-essential amino acids
  • most of the reaction of the glycolytic pathway are reversible
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

how long can glycolysis support strenuous activity?

A

2 mins

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

how is cardiac muscle adaptive for anaerobic performance?

A
  • does not fatigue like skeletal muscle
  • has low glycolytic activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

is glycolysis anaerobic or aerobic?

A

anaerobic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

as strenuousness of activity increases, what happens to the ratio of aerobic exercise compared to anaerobic exercise?

A

anaerobic glycolysis provides energy for activity almost entirely, then decreases as aerobic activity increases simultaneously.

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

what happens during anaerobic activity? (5)

A
  • production of NADH exceeds the capacity of the electron transport chain
  • pyruvate is converted to lactate by lactate dehydrogenase
  • this converts NADH back into NAD+, lowering the level of NADH
  • reduces intracellular pH
  • lactate diffuses out into bloodstream and is processed by the liver to produce glucose
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

what would the lactate levels be of someone that is untrained compared to someone that is trained or an athlete after completing endurance training?

A

the lactate levels would be higher

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

where is the site of glycolysis?

A

it occurs in the cytosol

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

what are the first 5 steps of glycolysis known as?

A

energy investment step (think of the ripcord for a motor to start)

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

what are the next 5 steps (6-10) of glycolysis known as?

A

energy generation

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

what occurs in the first step of glycolysis?

A

hexokinase reaction - phosphorylation of the hexoses (mainly glucose)

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

why is glucose converted in the first step?

A

converting it keeps the level of glucose low, so more glucose will enter the cell.
it is prevented from leaving the cell due to the charge the phosphate adds to the molecule.

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

where does the phosphate group come from in most steps of glycolysis?

A

ATP donates it but must be associated with Mg.
APT converts into ADP

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

when ATP converts into ADP, what is being donated?

A

phosphate

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

why must ATP be associated with Mg?

A

when Mg is not associated, there is no Mg-ATP complexed. With out the substrate, un-complexed ATP is a potent inhibitor of hexokinase.

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

how does hexokinase catalyse the first step?

A

by proximity effect - brings 2 substrates in close proximity

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

what inhibits hexokinase at the end of the first step?

A

inhibited by high concentration of product (G6P) compared to substrate

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

give differences between hexokinase and glucokinase.

A

Hexokinase​
-Km low, high affinity for glucose ​
- Non-specific, can phosphorylate any of hexoses​
- Present in tissues, supplies glucose to tissues even in low blood glucose concentration​
- Not affected by insulin ​
- Allosterically inhibited by glucose

Glucokinase​
- Km high, low affinity for glucose​
- Specific, can phosphorylate only glucose​
- Present in liver only​
- Helps drive movement of glucose from blood to cells after meal.​
- Stimulated by glucose and insulin​
- Not inhibited by glucose-6-phosphate

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

what occurs in the second step of glycolysis?

A

isomerization of glucose-6-phosphate to fructose-6-phosphate

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

what is the enzyme needed in step 2 of glycolysis?

A

phosphoglucose isomerase

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

what cofactor does phosphoglucose/phosphohexose isomerase (PGI) require for activity?

A

Mg2+

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what other roles does PGI have?

A
  • neural growth factor
  • driver of cancer metastasis and maturation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

what occurs in the third step of glycolysis?

A

transfer of phosphate group from ATP to C-1 of F6P to produce Fructose 1,6 bisphosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

what step is the first irreversible step?

A

glucose to g6p

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

what enzyme catalyses step 3?

A

Phosphofructokinase-1 check on ninja nerd

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

what activates Phosphofructokinase-1 in step 3?

A

fructose 2,6 biphosphate, ADP and AMP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

what occurs in step 4 of glycolysis?

A

splitting of fructose 1,6 bisphosphate into glyceraldehyde 3 phosphate and dihydroxy acetone phosphate (isomers)
conversion of aldose to ketose

30
Q

what enzyme catalyses step 4?

A

aldolase

31
Q

does step 4 require energy?

A

yes

32
Q

what occurs in step 5 of glycolysis?

A

Conversion of Dihydroxyacetone phosphate to glyceraldehyde 3 Phosphate

33
Q

what enzyme catalyses step 5?

A

Triose phosphate isomerase

34
Q

give a summary of the first 5 step of glycolysis (one word answer for each step).

A

phosphorylation
isomerisation
phosphorylation
cleavage/splitting
isomerisation

35
Q

what occurs in step 6 of glycolysis?

A

Conversion of GAP to Bisphosphoglycerate

36
Q

what enzyme catalyses step 6?

A

Glyceraldehyde-3-phosphate dehydrogenase

37
Q

what groups are added in step 6?

A

2 phosphate groups

38
Q

how is step 6 an energy yielding step?

A

inorganic phosphate is incorporated in the reaction without any use of ATP

39
Q

what does NAD+ do in step 6?

A

it is the cofactor which acts as an oxidising agent.
NAD+ —> NADH + H

40
Q

what occurs at step 7 of glycolysis?

A

Transfer of phosphoryl group from 1,3 bisphosphoglycerate to ADP generating ATP

41
Q

what enzyme is required for step 7?

A

Phosphoglycerate kinase

42
Q

is step 7 reversible?

A

yes

43
Q

how does step 7 generate ATP?

A

SUBSTRATE-LEVEL PHOSPHORYLATION

44
Q

what occurs in the 8th step of glycolysis?

A

Conversion of 3-phosphoglycerate to 2-phosphoglycerate

45
Q

what enzyme is required for step 8?

A

Phosphoglycerate Mutase

46
Q

what occurs at step 9 of glycolysis?

A

Dehydration of 2-phosphoglycerate (2-PG) to phosphoenolpyruvate (PEP)

47
Q

enzyme is required for step 9?

A

Enolase

48
Q

what occurs in step 10 of glycolysis?

A

Transfer of phosphoryl group from PEP to ADP generating ATP and Pyruvate.​

49
Q

enzyme is required for step 10?

A

Pyruvate Kinase

50
Q

2 steps of glycolysis produce ATP?

A

7 and 10

51
Q

give a summary of steps 6-10 of glycolysis (one word answer for each step).

A

oxidation and phosphorylation
substrate level phosphorylation
substrate level phosphorylation
isomerisation
dehydration

52
Q

how much ATP is produced and why?

A

energy investment phase produces 2 molecules of glyceraldehyde-3-phosphate.
double 2 ATP productions we see (7 and 10), 4 ATP is produced

53
Q

what happens to the 2 NADH molecules produced?

A

they are oxidised in the mitochondria under aerobic conditions

54
Q

if 2 NADH are oxidised in the mitochondria under aerobic conditions, how many molecules of ATP can be synthesized from their free energy?

A

6

55
Q

how does insulin stimulate step 1 and step 2?

A

Insulin stimulate Hexokinase & Glucokinase by converting glucose to glu-6-PO4​

Insulin stimulate Phosphofructokinase converting fru-6-PO4 to Fru-1,6 bisphosphate

56
Q

how does glycolysis stimulate step 2?

A

Glucagon stimulate liver glu-6-PO4 by converting glu-6-PO4 to glucose & fru-1,6- bisphosphate.

57
Q

inhibitors? do i need to know

A
58
Q

what are the two types of control for metabolic reaction?

A

substrate limited
enzyme limited

59
Q

what does substrate limited mean?

A

When concentrations of reactant and products in the cell are near equilibrium, substrate availability drive reaction rat

60
Q

what does enzyme limited mean?

A

When concentration of substrate and products are far away from the equilibrium, then it is activity of enzyme that decides the rate of reaction

61
Q

what 3 enzymes work comparatively slower and may limit glycolysis?

A

I. The hexokinase (HK)​

II. The phosphofructokinase (PFK)​

III. The pyruvate kinase

62
Q

how many molecules of pyruvate are produced from one molecule of glucose?

A

2

63
Q

where does aerobic respiration take place

A

mitochondria

64
Q

what happens to pyruvate once it enters the mitochondria?

A

pyruvate undergoes oxidative decarboxylation

65
Q

what is the chemical eq for the oxidative decarboxylation of pyruvate?

A

Pyruvate + NAD+ + CoA –>​ acetyl CoA + NADH + CO2

66
Q

what enzyme complex catalyses the oxidative decarboxylation of pyruvate in the mitochondria?

A

pyruvate dehydrogenase complex

67
Q

is the oxidative decarboxylation of pyruvate in the mitochondria reversible or irreversible?

A

irreversible

68
Q

what 3 enzymes make up the pyruvate dehydrogenase complex?

A

E1 = pyruvate dehydrogenase​

E2 = dihydrolipoamide transacetylase​

E3 = dihydrolipoamide dehydrogenase

69
Q

what happens during starvation?

A

circulating blood glucose levels are lower.
glucose becomes scarce.
PDC is activated by PDK to ensure there is better utilisation of fats as an energy source.
Tries to spare bodily stores of glycogen and glucose as well.

70
Q

what does calorimetry measure?

A

heat

APO510 - MEDICAL BIOCHEMISTRY (12 decks)

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