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P1 Spring 2024 > biochem exam 1 turning points > Flashcards

biochem exam 1 turning points Flashcards

1
Q

___ is formed by an essentially irreversible process and is the “glucose donor” in the synthesis of glycogen.

A. Glucose-1-phosphate
B. Glucose-6-phosphate
C. ADP-glucose
D. UDP-glucose

A

D. UDP-glucose

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2
Q

The primer and enzyme that begins the synthesis of glycogen is…

A. Glycogen phosphatase
B. Glycogen phosphorylase
C. Glycogen synthase
D. Glycogenin
E. Glycogenkinase

A

D. Glycogenin

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3
Q

For the transformation of 1 molecule of glucose to 2 molecules of pyruvate, how many ATPs are required & produced, respectively?

A. 0, 2
B. 0, 4
C. 2, 2
D. 2, 4
E. 4, 2

A

D. 2, 4

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4
Q

At which steps of glycolysis is ATP required/consumed?

A. 1, 3
B. 1, 6
C. 3, 6
D. 6, 7, 10
E. 7, 10

A

A. 1, 3

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5
Q

At which steps of glycolysis is ATP generated/formed?

A. None
B. 6, 7
C. 6, 10
D. 7, 10
E. 6, 7, 10

A

D. 7, 10

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6
Q

at which step of glycolysis is NADPH required/consumed

none
6
7
10

A

none

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7
Q

at which step of glycolysis is NADH generated/formed

none
6
7
10

A

6

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8
Q

if aldolase is absent or not functioning in a cell, whcih intermediate iin glycolysis is most likley to accumulate when glucose is catabolized

fru 1,6 bisphos
G3P
DHAP
PEP
Pyruvate

A

fru 1,6 bisphos

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9
Q

Under anaerobic conditions in human muscle cells, pyruvate is metabolized to…

A. Acetyl-CoA
B. Ethanol
C. Lactate
D. PEP
E. TPP

A

C. Lactate

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10
Q

In gluconeogenesis, instead of reversing the PEP→pyruvate reaction, pyruvate is converted to ___, which is then converted to PEP.

A. Ethanol
B. Malate
C. Lactate
D. Oxaloacetate

A

D. Oxaloacetate

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11
Q

the metabolism of 1 pyruvate to 1 oxaloacateta etc 1 PEP required

1 ATP
1 GTP
1 ATP + 1 GTP
2 ATP + 2 GTP
2 ATP equivalents

A

1 ATP + 1 GTP

2 ATP equivalents

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12
Q

For the synthesis of 1 molecule of glucose from pyruvate, how many ATP equivalents are required and produced, respectively?

A. 2, 4
B. 4, 0
C. 4, 2
D. 6, 0
E. 6, 2

A

D. 6, 0

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13
Q

For a given reaction, ∆H = -10.6 kJ/mol and ∆S = + 7.8 kJ/mol-K. This reaction is clearly…

A. Endothermic
B. Endergonic
C. Exergonic
D. None of the above

A

C

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14
Q

given the Keq for various rxns, and the mass action ratios in given cells, which of the following rxns will be very exergonic in these cells

A
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15
Q

given these conditions, which of the following wll happen inittailly

fru 6-phos (1.5M) to glu 6-phos (0.5M)
delta G = -4.4 kJ/mol

the rxn will proceed from left to right

the rxn will proceed from right to left

the system is at equilibium so there will be not net movement

A

the rxn will proceed from left to right

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16
Q

given these conditions, which of the following wll happen inittailly

fru 6-phos (0.2M) to glu 6-phos (1.8M)
delta G = +3.7 kJ/mol

the rxn will proceed from left to right

the rxn will proceed from right to left

the system is at equilibium so there will be not net movement

A

the rxn will proceed from right to left

17
Q

In the reaction: NAD+ <-> NADH, identify the oxidation direction, and identify the reduction direction.

A. Oxidation: L→R Reduction: R→L
B. Oxidation: R→L Reduction: L→R

A

B. Oxidation: R→L Reduction: L→R

18
Q

which of the following pairs of rxns is a futile (substrate) cycle

1,3 bisphosphoglycerate + ADP + Pi -> 3-phosphoglycerate + ATP 3-phosphoglycerate + ATP -> 1,3 bisphosphoglycerate + ADP +Pi

3-phosphoglycerate -> 2-phosphoglycerate
2-phosphoglycerate -> 3-phosphoglycerate

glyceraldehyde 3-phosphate + NAD+ + P -> 1,3 bisphosphoglycerate + NADH
1,3 bisphosphoglycerate + NADH -> glyceraldehyde 3-phosphate + NAD+ + PI

3-phosphoglycerate -> 2-phosphoglycerate
2-phosphoglycerate -> PEP + H2O

fructose 6-phos. + ATP -> fructose 1,6-bisphos. + ADP
fructose 1,6-bisphos. + H2O -> fructose 6-phos

A

fructose 6-phos. + ATP -> fructose 1,6-bisphos. + ADP
fructose 1,6-bisphos. + H2O -> fructose 6-phos

it was just one of the examples he gave honestly….

19
Q

Which of the following is true about the regulation of muscle hexokinase?

A. Elevated [glucose] increases activity
B. Elevated [glucose] decreases activity
C. Elevated [glc 6-phos] increases activity
D. Elevated [glc 6-phos] decreases activity

A

D. Elevated [glc 6-phos] decreases activity

yup, G6P will do a feedback inhibition onto hexokinase when there is too much of it so that glycolysis will stop

so hexokinase
- muscle: inhibited by G6P
- liver: activated by glucose

20
Q

Which of the following is true about the regulation of liver hexokinase?

A. Elevated [glucose] increases activity
B. Elevated [glucose] decreases activity
C. Elevated [glc 6-phos] increases activity
D. Elevated [glc 6-phos] decreases activity

A

A. Elevated [glucose] increases activity

21
Q

What effect does an elevated [AMP] have on PFK-1 activity? FBPase?

A. Increase, decrease
B. Decrease, increase
C. Increase, increase
D. Decrease, decrease

A

A. Increase, decrease

22
Q

You’re fasting, what are your enzymes PFK-1 and FBPase-1 doing?

A. FBPase-1 more active PFK-1 less active Gluconeogenesis

B. FBPase-1 more active PFK-1 less active Glycolysis

C. FBPase-1 less active PFK-1 more active Gluconeogenesis

D. FBPase-1 less active PFK-1 more active Glycolysis

A

A. FBPase-1 more active PFK-1 less active Gluconeogenesis

23
Q

an elevated [glucagon] leads to

an elevated [fru 2,6-BP]

a decrease in fru 2,6-BP

A

a decrease in fru 2,6-BP

BECAUSE fru 2,6-BP and AMP stimulate glycolysis and so more glucagon will decrease it

24
Q

at a relatively high [fru 2,6-BP]

the activity of PFK-1 is relatively high

the activity of PFK-1 is relatively low

A

the activity of PFK-1 is relatively high

25
Q

at a relatively low [fru 2,6-BP]

the activity of FBPase-1 is relatively high

the activity of FBPase-1 is relatively low

A

the activity of FBPase-1 is relatively high

26
Q

in the liver, increased blood [glucagon] leads to

allosteric activation of pyruvate kinase

allosteric inactivation of pyruvate kinase

covalent activation of pyruvate kinase

covalent inactivation of pyruvate kinase

A

covalent inactivation of pyruvate kinase

so glucagon regulates pyruvate kinase in the liver because glucagon activates PKA which will add a pi onto the pyruvate kinase and this will inactivate it
so the more glucagon, the more PKAs it will activate and thus will add a pi onto the pyruvate kinase to stop it from working and thus will block glycolysis

glucagon = no glycolysis

27
Q

Which of the following is correct about the regulation of glycogen phosphorylase? AMP promotes___; ATP promotes___

A. Activation, activation
B. Activation, inactivation
C. Inactivation, activation
D. Inactivation, inactivation

A

B. Activation, inactivation

28
Q

which of the following statements is true about PP1? it catalyzes

the activation of glycogen phosphorylase and activation of glycogen synthase

the activation of glycogen phosphorylase and inactivation of glycogen synthase

the inactivation of glycogen phosphorylase and activation of glycogen synthase

the inactivation of glycogen phosphorylase and inactivation of glycogen synthase

A

the inactivation of glycogen phosphorylase and activation of glycogen synthase

29
Q

Glucose ___ glycogen breakdown, and glucagon ___ glycogen synthesis

A. Promotes, promotes
B. Promotes, inhibits
C. Inhibits, promotes
D. Inhibits, inhibits

A

D. Inhibits, inhibits

30
Q

Consumption of sugar most clearly increase the risk for …

  1. Cancer
  2. Constipation
  3. Dental caries
  4. Heartdisease
  5. Hyperactivity
A
  1. Dental caries
31
Q

What is the recommended daily intake of carbohydrates for a healthy person who consumes 2000 kcal/day?

  1. ≤ 200 kcal
  2. 200-400kcal
  3. 450-650kcal
  4. 700-900kcal
  5. 900-1300 kcal
A
  1. 900-1300 kcal
32
Q

900-1300 kcal of carbohydrates is equivalent to how many grams?

  1. 90-130g
  2. 180-260g
  3. 225-325g
  4. 450-650g
  5. 900-1300 g
A

225-325g

33
Q

Consumption of which of the following is most likely to lower blood [cholesterol]

  1. Amylose
  2. Amylopectin
  3. Insoluble fiber
  4. Soluble fiber
  5. Sucrose
A
  1. Soluble fiber
34
Q

The Daily Value of Dietary Fiber is …

  1. 300mg
  2. 10g
  3. 25g
  4. 50g
  5. 100g
A
  1. 25g
35
Q

Which of the following contains no energy (kcalories)?

  1. Aspartame
  2. Isomalt
  3. Mannitol
  4. Saccharin
  5. Xylitol
A
  1. Saccharin

P1 Spring 2024 (57 decks)

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