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Biochem midterm exam 1 > Final exam > Flashcards

Final exam Flashcards

1
Q

What is the net yield of ATP after glycolysis?

A

2 ATP

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2
Q

What enzymes catalyzes the transfer of a phosphoryl group from ATP to glucose

A

hexinose

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3
Q

Phosphofructokinase (PFK) is allosterically activated by _____

A

AMP

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4
Q

Phosphofructokinase (PFK) is _ inhibited by __

A

ATP and citrate

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5
Q

What is glucose converted to in the skeletal muscle under anerobic conditions?

A

lactate

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6
Q

What is the purpose of co-factors chemical teeth?

A

broaden the range of enzymes’ catalytic properties

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7
Q

What are the two cofactor

A

metal ions and coenzymes

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8
Q

What are the different types of coenzymes

A

cosubtrates and Prosthetic groups

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9
Q

Define cosubstrates

A

loosely bound, cycle on & off

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10
Q

Define prosthetic

A

tightly/covalently bound

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11
Q

What are some examples of Metabolite coenzymes:

A

ATP, UDP-glucose, S-adenosylmethionine

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12
Q

What are some examples of Vitamin-derived coenzymes (water soluble)

A

Vitamins B and C

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13
Q

What are some examples of lipid soluble vitamin-derived coenzymes

A

vitamins` A, D, E, and K (

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14
Q

Acid-base catalysis

A

Partial proton donation (general acid catalysis) or abstraction (general base catalysis)

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15
Q

What amino acids participate in acid-base catalysis

A

Asp, Glu, Lys, Arg, and His

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16
Q

What makes a good catalyst

A

Good leaving group, reversibiliy of the bond, (how mobile electrons are).

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17
Q

How does covalent catalyst form

A

Via transient formation of covalent E-S intermediate

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18
Q

What is a covelent catalysis

A

a nucleophile attacks an electrophile and forms covalent bond with it

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19
Q

There are 2 classes of metal ion catalysis, what are those two classes?

A

Metalloenzymes and Metal-activated enzymes

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20
Q

What are the differences between Metal-activated enzymes and Metalloenzymes

A

Metalloenzymes are tightly bound and are transition metals. Metal-activated enzymes are loosely bound and are alkaine

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21
Q

What are the 3 ways that metal ion catalysis act

A

Bind to substrates (orient properly for reaction).
2. Transiently change redox state (mediate redox reaction).
3. Stabilize/shield negative charges.

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22
Q

What is the proximity and oreintation effects?

A

Binding to E forces substrate orient in a certain way  Rotational, translational motions cease
 active groups face each other  reaction

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23
Q

Is there a prefential binding for ES

A

yes, there’s an affinity for E in ES because there’s a higher chance to form product

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24
Q

What is Km ((Michealis constant)

A

enzyme binding affinity (higher Km=weaker affinity)

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25
Q

What is Vmax

A

maximum rate of the reaction

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26
Q

Vmax relates

A

Kcat and [Et] by Vmax = kcat[Et]

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27
Q

What is Kcat

A

(turnover number or catalytic constant) and the Speed of catalysis

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28
Q

Define kcat/KM

A

measure of catalytic efficiency of enzyme

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29
Q

What does Kcat measure

A

product formation, substrate turnover

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30
Q

What is the Michaelis-Menten equation

A

V = Vmax[S]/(KM+[S])`

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31
Q

When would the Michaelis-Menten equation be haf-maximal

A

[S] = KM

32
Q

what is the slope of Lineweaver-Burk plot
or double reciprocal plot

A

Km/Vmax

33
Q

What is the y-intercept of the Lineweaver -Burk plot

A

1/vmax

34
Q

What is the x-intercept of the Lineweaver

A

-1/Km

35
Q

What is the purpose of Lineweaver -Burk

A

Can determine KM and Vmax graphically

36
Q

What is competitive inhibition

A

the inhibtition is structurally similar to the substrate and competes with the substrate for active site binding

37
Q

What is competitve inhibtion impact on the reaction

A

reduces the steady state of ES, increases the Km, and no reaction happens if the inhibition binds to the active site

38
Q

How can the competitve inhibition be overcommed

A

increase the amount of substrate

39
Q

What is uncompetitve inhibitor

A

binds only to ES but not to any free enzyme

40
Q

What is the impact uncometitve inhibitor has on the reaction

A

Both KM and Vmax change,Does not change the slope (KM/Vmax), no reaction happens at ESI

41
Q

Defines Noncompetitive (mixed) inhibition

A

Binds both E and ES (somewhere, not in the active site)

42
Q

Non competitve inhibition impact on the reaction

A

slope becomes steeper
Y-intercept moves up, but X-intercept stays the same.
o Apparent Vmax ↓ but KM stays the same.

43
Q

What is an example of product inhibition

A

hexokinase by glucose-6-P

44
Q

Define feedback inhibition

A

cellular control mechanism in which an enzyme’s activity is inhibited by the enzyme’s end product.

45
Q

Where does glycolysis take place?

A

in the cytosal

46
Q

What are the products of glycolysis

A

2 ATP, 2 Pyr, 2 NADH, 4 H+, 2 H20

47
Q

Pyruvate kinase (step 10) is inhibitied by

A

ATP and acetyl-CoA

48
Q

Pyruvate kinase (step 10) is activated by

A

AMP and fructose-1,6-bisphosphate.

49
Q

What is the purpose of glycolysis?

A

provides precursor for aerobic catabolism
(TCA cycle

50
Q

What are the 2 stages of glycolysis

A

Investment and activation

51
Q

What is the product from the stage 1: investment

A

2 glyceraldehyde-3-phosphate (GAP)

52
Q

Stage 1 in glycolysis spends how many ATP

A

2 ATP for glucose activation

53
Q

What steps consume ATP in glycolysis?

A

are consumed in steps 1 and 3 by hexokinase (HK) and
phosphofructokinase (PFK)

54
Q

What steps are ATP synthesized in during glycolysis

A

steps 7&10 by phosphoglycerate kinase (PGK) and
pyruvate kinase (PK) via substrate-level phosphorylation

55
Q

What were the 3 irreversible control points in glycolysis

A

Hexokinase (step 1), Phosphofructokinase (step 3), Pyruvate kinase (step 10)

56
Q

Step 1 of Glycolysis results in

A

glucose-6-P

57
Q

In step 3 what catalyzes fructose-6-phosphate?

A

phosphofructokinase (PFK
)

58
Q

Where does the TCA cycle take place

A

in the mitochondrial matrix

59
Q

define reduction potential

A

tendency of a given reacting species to gain e - when paired with a
standard

60
Q

Positive reduction potential

A

tendency to attract/accept e- (reduced)

61
Q

Negative reduction potential

A

tendency to give up e- (oxidized

62
Q

What happens in a 2 half cell

A

e- always spontaneously flow from the half-rxn with more negative E o (donor) to
more positive E o (acceptor)

63
Q

Mechanims of ATP sysnthese

A

3 αβ protomers, 3 distinct sites, in 3 different conformations (states)

64
Q

O state of ATP sysnthase

A

open, inactive, cannot bind ADP

65
Q

L State of ATP synthase

A

loose binding, inactive, can bind ADP & Pi

66
Q

T state of ATP synthase

A

tight binding, active,can synthesize ATP

67
Q

What is the Michaelis-Menten equation

A

V = Vmax[S]/(KM+[S]

68
Q

Pyruvate kinase is inhibited by

A

ATP and acetyl-CoA

69
Q

Pyruvate kinase is activated

A

AMP and fructose-1,6-bisphosphate

70
Q

What steps in glycolysis go through

A

substrate-level phosphorylation

71
Q

What is substrate-level phosphorylation

A

the formation of ATP from ADP and a phosphorylated intermediate,

72
Q

What activates step 4 of the citric acid cycle?

A

AMP

73
Q

What inhibits step 4 of the TCA cycle

A

NADH and succinyl-CoA

74
Q

What is being oxidized in step 6 of the Kreb’s cycle

A

succinate

75
Q

What is being reduced in step 6 of the citric acid cycle ?

A

FAD to FADH2

76
Q

What process is succinate dehydrogenase is apart of besides the TCA cycle

A

electron transport chain

77
Q

Where does o

A

Biochem midterm exam 1 (10 decks)

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