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BCHM Exam 3 > Glycolysis 2 > Flashcards

Glycolysis 2 Flashcards

1
Q

Glycolysis

A

Breakdown of glucose monomer

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2
Q

Gluconeogenesis

A

Synthesizing glucose from scratch; used when the supply of glycogen is exhausted

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3
Q

Pentoses

A

5-c sugars generated in the Pentose phosphate pathway

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4
Q

What happens to free energy when it is released or consumed?

A

It is transferred to carriers like ATP and NADH

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5
Q

What is the rate of pathway flux controlled by?

A

Changing activity of individual enzymes

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6
Q

Steps 1-5 of glycolysis are known as

A

(Glucose to G-3-P) Energy investment phase because it requires 2 ATPs

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7
Q

Steps 6-10 of glycolysis are known as

A

G-3-P to pyruvate; energy payoff phase because they yield 4 ATP (net yield 2 ATP)

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8
Q

What three pathways are irreversible (have negative delta G values)?

A

1, 3, 10; flux control points that slow down the rxn

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9
Q

What is the direction controlled by in the reversible steps?

A

by the concentration of substrates and products (mass action ratio)

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10
Q

Where does regulation of the pathway occur

A

Step 3; irreversible ; flux control point / rate determining step

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11
Q

Regulation of PFK in bacteria

A

Regulated by allosteric effectors

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12
Q

What is the allosteric activator of PFK in bacteria?

A

ADP; increase in ADP means need more ATP therefore turn on pathway

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13
Q

What is the allosteric inhibitor of PFK in bacteria?

A

PEP; as PEP increases, too much product so much shut down pathway; ALSO ATP

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14
Q

What is PEP

A

Phosphoenolpyruvate

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15
Q

Regulation of PFK in Mammals

A

Fructose-2,6P2 is an activator

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16
Q

How does Fructose-2,6-bisphosphate get involved

A

When blood glucose is high, insulin is produced to process the glucose; Insulin stimulates PFK-2 to make Fructose-2,6-bisphosphate which then activates PFK-1(makes FBP in step 3) to send more glucose to be processed by glycolysis

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17
Q

F26BP is an allosteric activator of

A

PFK1

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18
Q

F26BP is an allosteric inhibitor of what

A

FBPase-1

19
Q

Why is step 1 and 10 not a control point?

A

Because they can be bypassed

20
Q

What are the 4 other fates of pyruvate

A
  1. acetyl CoA (aerobic, kreb)
  2. Oxaloacetate
  3. Lactate (anaerobic)
  4. Ethanol + CO2 (yeast)
21
Q

Pyruvate to oxaloacetate

A

Add CO2

22
Q

Pyruvate to Acetyl-CoA

A

Remove CO2

23
Q

Pyruvate to lactate

A

NADH + H+ to NAD+; reduced through lactate dehydrogenase (ANAEROBIC METABOLISM)

24
Q

Pyruvate to Ethanol

A

NADH to NAD+

25
Q

Where does the NAD+ produced from lactate

A

To be recycled back into GAPDH rxn in step 6 to continue glycolysis

26
Q

What is the benefit of making lactate from pyruvate

A

Keeps metabolism moving without needing more ATP

27
Q

What type of pathway is gluconeogenesis?

A

Anabolic pathway; costs energy and does not operate in the cell

28
Q

Reversal of glycolysis

A

Conversion of 2 Pyruvates to 1 glucose

29
Q

Gluconeogenesis cost vs glycolysis yield

A

Gluconeogenesis costs: 4 ATP, 2 GTP and 2 NADH
Glycolysis yields: 2 ATP and 2 NADH

30
Q

First step of storing glucose

A

Glucose-6-phosphate is converted to glucose-1-phosphate by phosphoglucose-mutase

31
Q

Second step of storing glucose

A

G-1-P is activated by UTP to make UDP-glucose and PP; PP (G= -33.5) is used to drive the rxn forward; (UDP glucose formation is irreversible)

32
Q

Third step of glycogen storage

A

Glycogen synthase links glucose units via alpha(1-4) and UDP functions as a leaving group

33
Q

How are the branch points in glycogen created?

A

Glycogen-branching enzyme moves 7 resides from the main chain to form a new branch

34
Q

Debranching enzyme to remove glucose in glycogen

A

A cleaving enzyme moves 3 residues to the main chain and then cleaves the alpha 1-6 branch point to release glucose

35
Q

How is stored glucose released

A

After phosphorylation yield G-1-P, Mutase converts it to G-6-P and phosphatase removes phosphate to make just glucose

36
Q

Why is G6P converted to glucose

A

Phosphorylated sugars cannot cross the plasma membrane

37
Q

What is the significance of ribose-5-phosphate

A

Sugar base to make all the nucleotide’s needed to form DNA and RNA

38
Q

Path 1 of PPP

A

Oxidative path; irreversible

39
Q

What does path 1 produce?

A

NADPH and ribulose-5-phosphate which may be reversibly converted to ribose-5-phosphate

40
Q

Path 2 of the PPP

A

The carbon rearrangement path

41
Q

What happens in path 2

A

2 F6P and one GAPare rearranged through a series of reversible reactions to Ru5P

42
Q

Path 3 of the PPP

A

When the cell needs NADPH but not ribose; G6P is converted to Ru5P which is converted to GAP and f6P by reversing the carbon rearrangement path

43
Q

What can NADPH be used for in the PPP?

A

To reduce ribose-5-phosphate to deoxyribose-5-phosphate

BCHM Exam 3 (7 decks)

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