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Final Exams > Biochemistry Final Exam 1 > Flashcards

Biochemistry Final Exam 1 Flashcards

1
Q

What 2 enzymes are the connection between glucose transport?

A

hexokinase and glucose-6-phosphatase

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2
Q

What kind of tissue/cell type is GLUT1 transporter present in?

A

most tissue/cells

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3
Q

What kind of tissue/cell type is GLUT3 transporter present in?

A

neuronal tissue/cells

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4
Q

What kind of tissue/cell type is GLUT2 transporter present in?

A

hepatocytes
pancreatic B cells

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5
Q

What kind of tissue/cell type is GLUT4 transporter present in?

A

skeletal myocytes
cardiomyocytes
adipocytes

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6
Q

What GLUT transporter is glucose sensitive?

A

GLUT2

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7
Q

What GLUT transporters are always near max rate regardless of [glucose]?

A

GLUT 1
GLUT 3

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8
Q

What GLUT transporter is insulin dependent?

A

GLUT4

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9
Q

When [insulin] increases, what happens to GLUT4?

A

GLUT4 vesicles fuse with cell membrane and access blood for insulin transport

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10
Q

When [insulin] decreases, what happens to GLUT4?

A

GLUT4 are sequestered into cell via vesicles

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11
Q

What is the appropriate glucose transporter for cells charged with blood glucose regulation?

A

one that is sensitive to changes in [glucose]

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12
Q

If glucose is modified (phosphorylation) after entering a cell, what happens to net transport?

A

remain favorable

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13
Q

What enzyme is involved in the commitment step in metabolism?

A

hexokinase

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14
Q

T/F? Hexokinase is the commitment step of glycolysis

A

false
its the commitment of using glucose so it cannot move outside of cell

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15
Q

Where is hexokinase I-III found?

A

most cell types

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16
Q

Hexokinase I-III are similar to which GLUTs and why?

A

GLUT 1 and 3
insensitive to [glucose]
always at max rate

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17
Q

What is hexokinase I-III inhibited by?

A

glucose-6-phosphatase

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18
Q

What GLUTs are used by hexokinase I-III?

A

GLUT 1
GLUT 3

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19
Q

What is another name for hexokinase IV?

A

glucose kinase

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20
Q

hexokinase IV is an _________ enzyme

A

allosteric enzyme

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21
Q

Hexokinase shows a ________ response to [glucose] which is S shaped on a plot

A

sigmoid response

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22
Q

is Hexokinase IV sensitive to [glucose]?

A

Yes

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23
Q

Is hexokinase IV inhibited by glucose-6-phosphatase like hexokinase I-III?

A

no

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24
Q

What cells is hexokinase IV present in?

A

hepatocytes
pancreatic B cells

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25
Q

Insulin signaling ___________ Hexokinase IV expression

A

increases

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26
Q

glucagon signaling ___________ hexokinase IV expression

A

decreases

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27
Q

Hepatocytes also produce glucokinase regulatory proteins (GKRP). How is it involved with hexokinase IV?

A

glucose and GKRP compete for hexokinase IV

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28
Q

Increased [glucose] = increased Hexokinase IV which is active where?

A

cytosol

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29
Q

decreased [glucose] = increased Hexokinase IV which is inactive where?

A

nucleus

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30
Q

What enzyme completes gluconeogenisis?

A

glucose-6-phosphatase

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31
Q

What cell type is glucose-6-phosphatase mainly found in?

A

heptatocytes

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32
Q

How does glucose-6-phosphatase allow glucose to cross membrane?

A

removes phosphate so glucose can cross membrane using GLUT2

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33
Q

What are the 2 types of control in glucose-6-phosphatase?

A

substrate level control
transcriptional level control

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34
Q

What is an example of substrate level control using glucose-6-phosphatase?

A

increased [G-6-P] = increased rate

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35
Q

What is an example of transcriptional level control using glucose-6-phosphatase?

A

increased glucagon = increased expression of G-6-P

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36
Q

Allosteric enzymes DO NOT follow Michelins-Menten Kinetics, it as a ____________ response

A

sigmodial response

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37
Q

Sigmodial response in allosteric enzymes [substrate] indicates _______________

A

positive cooperativity

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38
Q

What is positive cooperatively?

A

binding os substrate at one active site enhances binding at another active site

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39
Q

What are the 2 different symmetry models for positive cooperativity?

A

T – tight
R – relaxed

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40
Q

Which conformation of the symmetry model interacts poorly with the substrate?

A

T – tight

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41
Q

Can an enzyme have both conformations of the symmetry model?

A

no; not both

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42
Q

Which conformation of the symmetry model interacts well with the substrate?

A

R – relaxed

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43
Q

T/F? According to the symmetry model of allosteric enzymes, [T]/[R] is a large positive number

A

true

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44
Q

is the disassociation constant of the T conformation of the symmetry model large or smaller than R?

A

smaller because it interacts well with substrate

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45
Q

Allosteric _______ increase the cooperativity affect

A

increases

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46
Q

On a plot for the coopereativity affect, where is the line for an allosteric inhibitor is present and when an allosteric activator is present?

A

activator – on top
inhibitor – on botton

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47
Q

When an allosteric inhibitor is present, why is more [substrate] required?

A

more [s] is needed to overcome bias which will increased the cooperativity affect (get up the hill)

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48
Q

Allosteric activators prefer the R or T state?

A

R – relaxed

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49
Q

Do allosteric inhibitors increase/decrease the cooperativity affect?

A

decrease

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50
Q

For the enzyme phosphofructokinse-1, Glu goes the the ____ active site and Arg goes to the ____ active site

A

Glu – T
Arg – R

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51
Q

ATP is an allosteric inhibitor or activator?

A

BOTH

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52
Q

What is a major regulator enzyme of glycolysis/gluconeogensis?

A

F-2,6-BP

53
Q

PFK-2/FBPase-2 is regulated by _____________ modification

A

covalent modification (phos/dephos)

54
Q

Does insulin activate or inactivate PKA?

A

inactivate

55
Q

Does insulin activate or inactivate PPP-1?

A

activate

56
Q

increased insulin = fasting or well fed?

A

well fed

57
Q

increased glucagon = fasting or well fed?

A

fasting

58
Q

insulin present…
increase/decrease F-2,6-BP
increase/decrease PFK-1
increase/decrease FBPase
increase/decrease glycolysis
increase/decrease gluconeogensis

A

increase F-2,6-BP
increase PFK-1
decrease FBPase
increase glycolysis
decrease gluconeogensis

59
Q

Does glucagon activate or inactivate PKA?

A

activate

60
Q

Does glucagon activate or inactivate PPP-1?

A

inactivate

61
Q

Epinepherine has the same response in cardiomyocytes as _________ has in hepatocytes

A

glucagon

62
Q

gluconeogensis does not happen in ________cytes

A

cardiomyoctes

63
Q

Epinephrine presence __________ PKA and ________ PPP-1

A

activates PKA
inactivates PPP-1

64
Q

In the well fed state, insulin signaling __________ AKT (protein kinase B)

A

activates

65
Q

Pyruvate kinase is regulated by _____________ modification

A

covalent modification (phos/dephos)

66
Q

For pyruvate kinase deactivation, KD for ATP is high or low?

A

high

67
Q

For pyruvate kinase activation, KD for ATP is high or low?

A

low

68
Q

glucagon/epinepherine __________ PKA

A

activates

69
Q

glucagon/epinepherine ___________ PPP-1

A

inactivates

70
Q

insulin ____________ PKA

A

inactivates

71
Q

insulin ____________ PPP-1

A

activates

72
Q

What enzyme in gluconeogenisis is biotin dependent?

A

pyruvate carboxylase

73
Q

Pyruvate carboxylase is inactive without ____________

A

acetyl coA

74
Q

In the well fed state PEPCK increases/decreases?

A

decreases

75
Q

In the fasting state PEPCK increases/decreases?

A

increases

76
Q

What hexokinase is used in glycogensis?

A

HK IV

77
Q

In glycogenisis, UDP glucose requires inorganic ______________

A

pyrophosphatase

78
Q

What is UDP-glucose?

A

active form of glucose

79
Q

what is the branching enzyme in glycogenesis?

A

glycogen synthase

80
Q

when glucose is debranched, what happens to its solubility?

A

increases solubility

81
Q

what linkage does the branching enzyme create for glucose?

A

alpha-1,4 linkage

82
Q

What is the advantages of branching glucose for glycogenisis?

A

helps it fit into hepatocytes
allows more places to phosphorylate

83
Q

What is the purpose of glycogenlysis?

A

glycogen previously stored by the liver is broken down to glucose and dispersed throughout the body (body needes energy)

84
Q

what is the purpose of glycogenisis?

A

storing excess glucose for use by the body at a later time

85
Q

All the steps in dietary starch digestion are __________

A

hydrolytic

86
Q

In dietary starch digestion, alpha-amylase hydrolyzes alpha-________-glycosidic bond

A

alpha-1,4-glycosidic bond

87
Q

In dietary starch digestion, alpha 1,6-glucosidase remove the _________ point

A

branch point

88
Q

In dietary starch digestion, alpha-1,4-gluconotransferase removes the ___________ branch

A

limit branch

89
Q

what is the debranching enzyme in glycogenolysis?

A

alpha-1,6,glucosidse

90
Q

what order does the debranching enzyme remove the linkages?

A

alpha-1,4-glycosidc then alpha-1,6

91
Q

when talking about glycogen, more phosphorylation means more or less activity?

A

less activity

92
Q

in glycogenisis, when glycogen synthase is phosphorylated, is it activated or deactivated?

A

inactivate

93
Q

is glycogen phosphorylase a or b the more active form?

A

a

94
Q

is glycogen phosphorylase a or b sensitive to internal conditions?

A

a

95
Q

is glycogen phosphorylase a or b apart of the fight/flight response?

A

a

96
Q

is phosphorylase kinase activated or inhibited by PKA?

A

activated

97
Q

is phosphorylase kinase activated or inhibited by Ca2+?

A

activated

98
Q

in glycogenolysis, is PPP-1 activated or inhibited by insulin?

A

activated

99
Q

in glycogenolysis, is PPP-1 activated or inhibited by epinephrine and glucagon?

A

inhibited

100
Q

is PPP-1 or PKA involved in the fight or flight response for glycogen?

A

PKA

101
Q

What is the only hydrolytic step in glycogenlysis?

A

alpha-1,6-glucosidase

102
Q

T/F? Alanine increases positive cooperatively in pyruvate kinase activity

A

true

103
Q

T/F? hexokinase catalyzes the commitment step to glycolysis

A

false

104
Q

T/F? pyruvate kinase in adipocytes is regulated by phosphorylation/dephosphorylation

A

false

105
Q

T/F? glycogen store in hepatocytes can be used as a source of glucose to sustain red blood cells during fasting

A

true

106
Q

T/F? glucose-6-phosphatase is an enzyme only found in cardiomyocytese

A

false

107
Q

T/F? glycogen stored in skeletal muscle cells is broken down primarily by hydrolysis reactions

A

false

108
Q

T/F? glycogen phosphorylase uses inorganic phosphate as a phosphoryl donor

A

true

109
Q

What is the delta G for pyruvate carboxylase?

A

negative

110
Q

What is the delta G for phosphoglucomutase?

A

0

111
Q

What is the delta G for fructose-1,6,bisphosphatase?

A

negative

112
Q

What is the delta G for UDP-glucose pyrophosphorylase?

A

0

113
Q

is pyruvate kinase inhibited or activated by being phosphorylated?

A

inhibited

114
Q

What are some kinases involved in muscle contraction?

A

Ca2+ / calmodium
PKA
phosphorylase kinase
PFK-1

115
Q

What kinases will increase in activity if epinephrine is present?

A

Ca2+ / calmodium
PKA
phosphorylase kinase

116
Q

What is the substrate for glycogenin?

A

UDP-glucose

117
Q

When insulin is signaling, what happens to phosphorylase kinase activity?

A

increases

118
Q

When insulin is signaling, what happens to glycogen synthase kinase activity?

A

decreased

119
Q

What is the role of glycogenin in glycogen metabolism?

A

it primes glycogen synthesis by building an 8-mer chain of glucose attached to its own Tyr residue (glycogen synthesis cannot start without it)

120
Q

Suppose cardiomyocytes are stimulated by epinetherine; PKA activity will increase or decrease?

A

increase

121
Q

Suppose cardiomyocytes are stimulated by epinetherine; pyruvate kinase activity will be phosphorylated or dephosphorylated?

A

dephosphorylated

122
Q

Suppose cardiomyocytes are stimulated by epinetherine; PFK-2/FBPase-2 will be phosphorylated or dephosphorylated?

A

phosphorylated

123
Q

Suppose cardiomyocytes are stimulated by epinetherine; the concentration of F-2,6-BP will increase or decrease?

A

increase

124
Q

If there is too much PFK-2 and not enough FBPase-2 what will happen to glucose metabolism?

A

glycolysis will be unregulated

125
Q

What happen if pyruvate kinase cannot be phosphorylated in glucose metabolsim?

A

glycolysis will be unregulated

126
Q

if glycolysis is inhibited what happens to glucose uptake?

A

glucose uptake would decrease

127
Q

If PFK-1 is inhibited what happens to glucose uptake?

A

F-6-P and G-6-P would accumulate and are inhibitors of HK I-III so glucose accumulates and transport stops

128
Q

In cardio

A

Final Exams (1 decks)

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