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MCAT > Enzymes and Metabolism > Flashcards

Enzymes and Metabolism Flashcards

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MCAT flashcards
1
Q

How can competitive inhibitors be overcome?

A

increase substrate concentration

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2
Q

How do non-competitive inhibitors work?

A

bind to allosteric site and destroy active site of enzyme

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3
Q

What is the effect of competitive inhibitors on the Km of an enzyme?

A

Competitive Inhibitors:

  • decrease affinity
  • thus increase Km of enzyme
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4
Q

What is the effect of competitive inhibitors on the Vmax of an enzyme?

A

Competitive Inhibitors:

-do not change Vmax because Vmax is the rate when you have an infinite amount of substrate

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5
Q

What are the x-axis and y-axis on an enzyme curve?

A

X-Axis: Substrate Concentration

Y-Axis: Rate

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6
Q

What is Vmax?

A

Vmax is the rate when substrate concentration is at infinity (i.e. don’t have to wait for substrate)

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7
Q

What is the effect of non-competitive inhibitors on the Km of an enzyme?

A

Non-competitive Inhibitors:

  • no effect on affinity
  • thus no effect on Km
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8
Q

What is the effect of non-competitive inhibitors on the Vmax of an enzyme?

A

Non-competitive inhibitors:

-decrease Vmax of an enzyme

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9
Q

What is the activation energy of an enzyme?

A

Energy required to align the active site and substrate.

(enough collisions for alignment)

(breaks bonds if needed)

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10
Q

What is glucokinase?

A

Glucokinase is the first enzyme in glycolysis pathway of the liver.

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11
Q

Is the Km of glucokinase low or high?

A

Glucokinase:

  • has low affinity
  • thus high Km
  • because if there is a low amount of glucose you don’t want liver to process it
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12
Q

Is the Vmax of glucokinase low or high?

A

Glucokinase:

  • high Vmax
  • so if there is a ton of glucose, liver will process it
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13
Q

What is Hexokinase?

A

Hexokinase is the first enzyme in glycolysis in muscles and other tissues.

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14
Q

Describe the Km and Vmax of Hexokinase.

A

Hexokinase:

  • high affinity, so low Km
  • does not have high Vmax
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15
Q

Is glucose oxidized or reduced in glycolysis?

A

oxidized

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16
Q

GLYCOLYSIS:

IN: ?

OUT: ?

A

GLYCOLYSIS:

IN: GLUCOSE, 2 ATP, 2 NAD+

OUT: 2 PYRUVATE, 4 ATP, 2 NADH

NET: 2 ATP

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17
Q

How do we know that pyruvate is a high energy molecule?

A

Pyruvate is a high energy moleecule because in order to make it, we didn’t produce CO2 and CO2 is the most oxidized form of carbon. So pyruvate still has high energy electrons.

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18
Q

What happens to pyruvate if there is no oxygen?

A

Pyruvate turns into lactic acid because of Le Chat’s Principle.

We regenerate NAD+ to keep glycolysis running.

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19
Q

Where does fermentation happen?

A

Cytoplasm

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20
Q

FERMENTATION

IN: ?

OUT: ?

A

FERMENTATION

IN: PYRUVATE, NADH

OUT: LACTIC ACID, NAD+

21
Q

What are the reducing agents and oxidizing agents of fermentation?

A

Oxidizing Agent: Pyruvate

Reducing Agent: NADH

22
Q

Can oxidation and reduction agents ever be products?

A

No, always reactants

23
Q

If there is oxygen, where does pyruvate go?

A

Mitochondrial Matrix

24
Q

What happens to pyruvate in the matrix?

A

In matrix, pyruvate becomes Acetyl CoA

25
Q

Purpose of PDC

A
  • remove CO2 from pyruvate
  • oxidize the carbons of pyruvate
26
Q

PDC

IN: ?

OUT: ?

A

PDC

IN: PYRUVATE, NAD+

OUT: CO2, ACETYL COA, 2 NADH

27
Q

What is the reducing agent in PDC?

A

NAD+ is the reducing agent (produces NADH).

28
Q

What becomes of Acetyl CoA?

A

goes to Kreb’s Cycle

29
Q

KREB’S CYCLE

IN: ?

OUT: ?

A

KREB’S CYCLE

IN OUT

ACETYL COA ⇒ 2 CO2

3 NAD+ ⇒ 3 NADH

1 FAD+ ⇒ 1 FADH2

1 GDP ⇒ 1 GTP

ALL PER SPIN SO x2- 6 NADH, 2 FADH2, 2 GTP (2 ATP)

30
Q

Products of Kreb’s Cycle

A

2 CO2

6 NADH

2 FADH2

2 GTP (2 ATP)

31
Q

What is the term for how ATP is made in ETC?

A

Oxidative Phosphorylation

32
Q

Products of Glucose Metabolism

A

10 NADH

2 FADH2

4 ATP NET

(6 SLPS: 4 GLYCOLYSIS AND 2 KREB’S)

33
Q

What gets sent to ETC?

A

Reducing Agents

NADH and FADH2

34
Q

Where does the ETC take place?

A

inner mitochondrial membrane

35
Q

What drives Complex 5?

A

Proton Gradient (not ATP)

pulls ADP and P together

36
Q

How is the proton gradient set up in ETC?

A

Complex 1, 2, and 4 are proton pumps.

37
Q

Where do NADH electrons go? What happens?

A

Complex 1 which gets reduced and becomes a proton pump.

Pumps protons from the matrix to inner mitochondrial space.

38
Q

What happens to the protons that were pumped?

A

Protons diffuse back through Complex 5 (ATP Synthase) and ATP is made (ferris wheel)

39
Q

How does the same electron go from Complex 1 to 3 to 4?

A

Cytochrome carrier

40
Q

Where does an electron go after Complex 4?

A

Complex 4 dumps the electron onto oxygen to form water.

41
Q

What is the final electron acceptor in ETC? Why?

A

Oxygen is the final electron acceptor in ETC because it has the highest reduction potential (i.e. wants electrons the most)

42
Q

How many pumps did NADH’s electrons stimulate?

A

3 (1,3,4)

43
Q

How many ATP’s does the pumping of one proton yield?

A

1 pump pumps enough protons to make 1 ATP.

Thus,

1 NADH yields 3 ATPs

1 FADH2 yields 2 ATPS

44
Q

What is the purpose of Complex 2?

A

Complex 2 accepts electrons from FADH2.

It is not a proton pump.

C2 to C3 to C4.

Hits 2 proton pumps.

45
Q

How many ATP result from the NADH made in glycolysis?

A

each NADH does not yield 3 ATP because it costs 1 ATP to transport to matrix

2 NADH = 2 ATP net

46
Q

What happens to the complexes if there is no oxygen?

A

If there is no oxygen, the complexes will remain in their reduced stated.

NADH will dump its electrons back onto pyruvate and ferment.

47
Q

What is Beta Oxidation?

A

Beta oxidation is the breaking down of fats.

48
Q

What is the product of Beta Oxidation?

A

Acetyl CoA (a lot of it because of all the carbons from the fatty acid)

49
Q
A

MCAT (7 decks)

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