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Biochemistry-Exam 2 > Glycolysis Pathway > Flashcards

Glycolysis Pathway Flashcards

0
Q

Second step of glycolysis

A

Glucose-6-phosphate to Fructose-6-phosphate via phosphoglucose isomerase (isomerization reaction)

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1
Q

First step of glycolysis

A

D-Glucose to Glucose-6-phosphate via Hexokinase (or glucokinase in liver) and consumes ATP

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2
Q

What is the third step of glycolysis?

A

Fructose-6-phosphate to Fructose-1,6-bisphosphate via phophofructokinase-1 and ATP

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3
Q

What is the 4th step of glycolysis?

A

Fructossse-1,6-bisphosphate to either dihydroxyacetooone phosphate or glyceraldehyde 3-phosphate via aldolase

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4
Q

Dihydroxyacetone phosphate is isomerized…

A

By triose phosphate isomerase to glyceraldehyde 3-phosphate. This happens preferentially because glyceraldehyde 3-phosphate is being removed

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5
Q

What is the 5th step of glycolysis

A

Glyceraldehyde 3-phosphate is made into 1,3-Biphosphoglycerate via glyceraldehyde 3-phosphate dehydrogenase consuming a phosphate and making NADH and H from NAD

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6
Q

What is the 6th step of glycolysis

A

1,3-biphosphoglycerate to 3-phosphoglycerate via phosphoglycerate kinase making an ATP from ADP

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7
Q

7th step of glycolysis

A

3-phosphoglycerate to 2-phosphoglycerate by phosphoglycero-mutase

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8
Q

8th step of glycolysis

A

2-phosphoglycerate is made to phosphoenol-pyruvate via enolase and loss of water

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9
Q

What is the 9th step of glycolysis?

A

Phosphoenol-pyruvate is made to pyruvate via pyruvate kinaqse and production of ATP from ADP

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10
Q

What steps produce ATP via substrate level phosphoyrlation

A

1,3-biphosphoglycerate to 3-phosphoglycerate and phosphoenol-pyruvate to pyruvate

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11
Q

What two enzymes are part of the substrate level phosphoylation?

A

Phosphoglycerate kinase and pyruvate kinase

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12
Q

What step consumes ATP in glycolysis?

A

D-glucose to Glucose-6-phosphate

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13
Q

What enzyme requires ATP?

A

Hexokinase (or glucokinase in liver)

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14
Q

What are the three irreversible steps in glycolysis?

A

D-Glucose to glucose-6-phosphate; Fructose 6-phosphate to Fructose 1,6-biphosphate; Phophoenol-pyruvate to pyruvate

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15
Q

What step produces NADH + H?

A

Glyceraldehyde 3-phosphate to 1,3-biphosphoglycerate via glyceraldehyde 3-phosphate dehydrogenase

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16
Q

What enzyme is responsible for making NADH in glycolysis?

A

Glyceraldehyde 3-phosphate dehydrogenase

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17
Q

How many pyruvates are made per glucose molecule?

A

Two

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18
Q

What is the net production of ATP in glycolysis?

A

2 ATP per glucose (4 out-2 in)

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19
Q

What is the rate limiting step in glycolysis?

A

Fructose 6-phosphate to Fructose 1,6-biphosphate via PFK-1 and consuming ATP

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20
Q

What would be a morphological defect due to hexokinase mutation?

A

Anemia in RBC

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21
Q

What would be the result of Pyruvate kinase defect?

A

Probably lead to RBC anemia but also may contribute to increase in 2,3-BPG (everything above roadblock is accumulated and this is last step in glycolysis)

22
Q

1,3-Bisphosphoglycerate can be made into what besides 3-phosphoglycerate?

A

Via mutase it van be made to 2,3-biphosphoglycerate.

23
Q

2,3-bisphosphoglycerate is reintroduced to glycolysis how?

A

Via water and phosphotase into 3-phosphoglycerate

24
Q

T or F: Production of 2,3-BPG and reintroduction via phosphotase at 3-phosphoglycerate level costs 1 ATP from glycolysis

A

T; skips the phosphoglycerate kinase step

25
Q

T or F: The three irreversible steps of glycolysis are regulated by effector molecules and indirectly by hormones

A

T

26
Q

What regulates glucokinase?

A

High Km of glucokinase is a self-regulator, no direct effector

27
Q

What regulates hexokinase?

A

Accumulation of Glucose 6-phosphate (negative feedback inhibition)

28
Q

Phosphofructokinase-1 is regulated by?

A

Positively: AMP, Fructose-2,6-P
Negatively: ATP, Citrate (lots of Krebs going on)

29
Q

Pyruvate kinase is regulated by?

A

Positively: F-1,6-P
Negatively: Phosphoylation via cAMP-dependent pathways
Alanine (this is because alanine and pyruvate are interchangeable since they are isomers)

30
Q

cAMP-dependent phosphorylation is important in regulating pyruvate kinase where?

A

In the liver, prevents consuming glucose when body needs it

31
Q

Describe the cAMP cascade

A

Hormone hits receptor that is coupled to G-protein coupled receptor. Activates G-protein to release G-alpha from G-beta and gamma (GDP to GTP). This activates adenylyl cyclase to make ATP into cAMP

32
Q

What enzyme is responsible for making cAMP from ATP?

A

Adenylyl cyclase

33
Q

Describe the structure of G-protein?

A

Alpha,beta, and gamma subunits.

34
Q

Compare and contrast active and inactive G-protein

A

Inactive: All three subunits together, alpha linked to GDP
Active: Alpha separates from gamma and beta when Alpha is conjoined with GTP

35
Q

Describe the function of cAMP

A

cAMP interacts with cAMP-dependent protein kinase A (makes catalytic subunits active by phosphorylating the regulatory subunits) which then phoysphorylates protein substrates leading to intracellular effects. Turned off by protein phosphatases.

36
Q

What happens in the liver when high glucose?

A

High glucose=high insulin=low cAMP=low PKA=low phoshporylation of PFK2=high activity of PFK2=high F2,6BP production which activates glycolysis

37
Q

What happens in the liver with low glucose?

A

Low Blood sugar=cAMP cascade=PFK2 is phosphorylated to be inactive=little F2,6BP produced=Gylcolysis is not activated

38
Q

T or F: Insulin opposes the cAMP cascade

A

T

39
Q

Describe the process of insulin triggered cell response

A

Insulin binds receptor and subunits phosphorylate themselves at tyrosine residues, the subunits also phosphorylate other protein kinases to produce cellular response of reversal of glucagon and stimulation of glucose transport via GLUT4

40
Q

Describe the structure of PFK-2

A

Bound to FBP-2. When phosphorylated, PFK-2 is inactive and FBP-2 is active (bifunctional enzyme).

41
Q

What happens from a regulatory stance of PFK-1 when insulin is high and glucagon is low?

A

Low glucagon means little cAMP production. High insulin means reduced levels of active PKA leading to dephosphorylation of PFK2 leading to activation of the Fructose 6-phosphate to Fructose 2,6-bisphosphate pathway.

42
Q

T or F: Insulin increases glycolysis

A

T

43
Q

T or F: Elevated levels of Fructose 2,6-biphosphate increase PFK-1 activity

A

T

44
Q

In humans, what three products can pyruvate be converted to following glycolysis?

A

Lactate, Acetyl CoA, and Oxaloacetate

45
Q

How is pyruvate converted to lactate?

A

By lactate dehydrogenase, regenerates NAD from NADH and H

46
Q

Describe an instance where lactate is produced

A

Decreased O2, less ATP, inc lactate, H accumulated

47
Q

How is pyruvate made to acetyl CoA?

A

Pyruvate dehydrogenase complex

48
Q

T or F: pyruvate to lactate is reversible

A

T

49
Q

What regulates Pyruvate dehydrogenase?

A

Inhibited: Acetyl CoA

Is source of acetyl CoA for krebs and fatty acid synthesis

50
Q

How is pyruvate made into oxaloacetate?

A

Pyruvate carboxylase consumes CO2 to replenish TCA cycle intermediates

51
Q

Pyruvate carboxylate does?

A

Activated by Acetyl CoA and replenishes TCA intermediates, provides substrates for gluconeogenesis

52
Q

What is the net yield of NADH when glucose 6-phosphate is converted to lactate by anaerobic glycolysis?

A

0

53
Q

The committed step of glycolysis is?

A

PFK-1 step

Biochemistry-Exam 2 (14 decks)

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