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DEN 7101F - Human Structure and Function > Exam 2 11/3 Howard > Flashcards

Exam 2 11/3 Howard Flashcards

1
Q

Glycogenolysis

A

Glycogen breakdown

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2
Q

Glycogenesis

A

Glycogen synthesis

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3
Q

Glycogen metabolism is highly ___ and needs to respond to ____

A

regulated; hormones and metabolites

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4
Q

Where are glycogen reducing ends found

A

In a circle all around the glycogen molecule

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5
Q

If glycogenolysis is on, glycogenesis should be

A

Off (and vice versa)

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6
Q

Where is glycogen mainly found

A

Muscle and liver

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7
Q

Free anomeric carbon is

A

Reducing end

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8
Q

Why does the liver store glycogen

A

Needs to be able to maintain blood glucose between meals

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9
Q

Muscle stores glycogen for:

A

Its own energy needs

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10
Q

3 steps of glycogen breakdown

A
  1. release of G1P
  2. Remodeling of glycogen
  3. Formation of G6P
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11
Q

Fate of G6P

A
  1. fuel for ATP generation
  2. converted into glucose3
  3. PPP to generate NADPH or ribose
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12
Q

Glycogen degradation occurs at

A

Non-reducing end

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13
Q

Enzyme used to break down glycogen

A

Glycogen phosphorylase

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14
Q

Glycogen phosphorylase breaks down glycogen by ____ to form what molecule?

A

Phosphorylytic cleavage; G1P

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15
Q

In order to perform phosphorolytic cleavage of glycogen, it must use what phosporyl source?

A

Direct phosphoryl group donation (not from ATP!!)

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16
Q

Pyridoxal phosphate (PLP) is a derivative of

A

Pyridoxine (vitamin B6)

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17
Q

____ requires Pyridoxal phosphate (PLP)

A

Glycogen phosphorylase

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18
Q

Where does glycogen phosphorylase stop?

A

4 residues away from a branch point

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19
Q

Transferase

A

Shifts a block of three glycosyl residues

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20
Q

alpha 1,6 glucosidase

A

Hydrolyzes alpha 1,6 glycosidic bond (now is just a lone glucose molecule

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21
Q

In eukaryotes, _____ and ____ is a single bifunctional enzyme during glycogen debranching

A

transferase, alpha 1,6-glucosidase

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22
Q

Phosphoglucomutase converts ____ into ____

A

G1P to G6P

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23
Q

Glycogen phosphorylase is a ____ (structure)

A

dimer

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24
Q

Glycogen phosphorylase - allosteric _____

A

Energy state

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25
Q

Glycogen phosphorylase undergoes ______ in response to hormonal signals

A

reversible phosphorylation

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26
Q

Which phosphorylase state is phosphorylated and where?

A

Phosphorylase a; at a serine 14 reside in each subunit

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27
Q

What phosphorylates Glycogen phosphorylase

A

phosphorylase kinase

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28
Q

Phosphorylase a favors

A

R state

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29
Q

Phosphorylase b favors

A

T state (taut)

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30
Q

Glycogen phosphorylase has _____ specificity

A

Tissue

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31
Q

Phosphorylase b is found in

A

Muscle

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32
Q

In muscle, a low energy charge (represented by _____) favors the transition to _____

A

high conc of AMP; R state

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33
Q

What can increase epinephrine

A

fear or excitement of exercise

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34
Q

If epinephrine is increased (a ____ response), _____ phosphorylates to _____ form

A

hormonal; muscle phosphorylase; phosphorylase a

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35
Q

Phosphorylase a is found in

A

Liver

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36
Q

In liver phosphorylase, when glucose is already abundant, _____ is not mobilized because _____ shifts the equilibrium to the ___ state which inactivates the enzyme

A

glycogen; glucose; T

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37
Q

Glycogen synthesis is done by what enzyme

A

glycogen synthase

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38
Q

____ is reciprocally regulated

A

Glycogen synthesis

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39
Q

UDP glucose is

A

An activated form of glucose (activated glucose donor)

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40
Q

How is UDP glucose made (enzyme and starting substrate)

A

Enzyme - UDP-glucose pyrophosphorylase
Starts from G1P

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41
Q

Phosphoglucomutase converts G1P into

A

G6P

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42
Q

_____ catalyzes transfer of glucose from UDP-glucose

A

Glycogen synthase

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43
Q

Glycogen has ____ reducing end(s) and ___ non-reducing end(s)

A

1 reducing, 2 non-reducing

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44
Q

phosphorylase a is usually ___________

A

active

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45
Q

phosphorylase b is usually _________________

A

inactive

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46
Q

phosphorylase a favors the ____ state

A

R state (relaxed)

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47
Q

phosphorylase b favors the ____ state

A

T state (taut)

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48
Q

A low energy charge, represented by high concentrations of AMP, favors the transition to the ___ state (more active) of muscle phosphorylase

A

R state

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49
Q

Fear or the excitement of exercise increases epinephrine: phosphorylates to Phosphorylase ____ form: hormonal response (in muscles)

A

A form (active)

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50
Q

Branching increases the _____________ of glycogen; inc. rate of synthesis and degradation

A

Solubulity

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51
Q

Is glycogen synthase a phosphorylated? Is it active or inactive?

A

NOT phosphorylated, active

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52
Q

Is glycogen synthase b phosphorylated? Is it active or inactive?

A

phosphorylated, NOT active

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53
Q

Is phosphorylase a phosphorylated? Is it active or inactive?

A

phosphorylated, active

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54
Q

Is phosphorylase b phosphorylated? Is it active or inactive?

A

NOT phosphorylated, NOT active

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55
Q

The Pentose Phosphate Pathway is also called…..

A
  • Phosphogluconate pathway
  • Hexose monophosphate shunt
56
Q

The Pentose Phosphate Pathway is a major source of ____________ for reductive biosynthesis

A

NADPH

57
Q

What pathway provides Ribose for RNA, DNA, ATP, NADH, FAD, and CoEnzyme A synthesis?

A

Pentose Phosphate Pathway

58
Q

The enzymes involved in the pentose phosphate pathway are ____________ enzymes

A

Cytoplasmic

59
Q

Does the pentose phosphate pathway consume or produce ATP?

A

NO

60
Q

The oxidative phase of the pentose phosphate pathway generates what?

A

NADPH

61
Q

The nonoxidative phase of the pentose phosphate pathway interconverts _______________

A

Phosphorylated sugars

62
Q

True or False: the two phases of the pentose phosphate pathway can function together or independently depending on metabolic needs

A

True

63
Q

What controls the rate of the pentose phosphate pathway?

A

Level of NADP+

64
Q

Flow of __________________ depends on the Need for NADPH, ribose 5-phosphate, and ATP (pentose phosphate pathway)

A

G6P

65
Q

If much more ribose 5-phosphate is needed than NADPH: ribose 5-phosphate is made ______________ NADPH synthesis (Mode 1 pentose phosphate)

A

Without

66
Q

If need for NADPH and ribose 5-phosphate is equal, then _____________ are made (Mode 2 pentose phosphate)

A

Both

67
Q

If much more ___________ is needed (Mode 3 pentose phosphate)

A

NADPH

68
Q

IF both NADPH and _____ is needed (Mode 4 pentose phosphate)

A

ATP

69
Q

What are sources of triglycerides?

A
  • Diet
  • Synthesis and storage
70
Q

Where are triglycerides found in the cell?

A

Cytosol of adipose cells; muscle

71
Q

What are efficient energy stores that are:
-Reduced
-Anhydrous

A

Triglycerides

72
Q

triglycerides are broken into what by hormone sensitive lipases?

A

Glycerol and free fatty acids (and albumin)

73
Q

What are the “fates” of triglyceride?

A
  1. glycerol goes to glycolysis/gluconeogenesis (in liver)
  2. fatty acids (ffa) go to fatty acid oxidation
74
Q

Glycerol is absorbed into the liver and converted into what intermediate of glycolysis/gluconeogenesis?

A

glyceraldehyde 3-phosphate

75
Q

What is the first stage of fatty acid oxidation?

A

ffa converted to fatty acyl CoA

76
Q

What is the 2nd stage of fatty acid oxidation?

A

b-oxidation and Acetyl CoA production

77
Q

What is the 3rd stage of fatty acid oxidation? (after TCA cycle)

A

Electron transport to generate a proton-motive force

78
Q

What is the 4th stage of fatty acid oxidation? (after TCA cycle)

A

ATP synthesis

79
Q

What is the 4th stage of fatty acid oxidation? (after TCA cycle)

A

ATP synthesis

80
Q

Fatty acids use _____ to bind to CoA and form Acyl CoA

A

ATP (forms thioester linkage)

81
Q

Where does the reaction between fatty acids and CoA occur?

A

Outer mitochondrial membrane

82
Q

How do acyl groups enter mitochondria?

A
  • Fatty acid conjugated to carnitine
  • Translocase exchanges acyl carnitine for carnitine
  • Re-form Acyl CoA in mito matrix
83
Q

Where does beta oxidation occur?

A

mitochondria

84
Q

beta oxidation of fatty acids is a repetition of sequence of ____ reactions

A

4

85
Q

What happens in beta oxidation of fatty acids?

A
  • Acetyl CoA enters TCA
  • NADH and FADH2 carry electrons to oxidative phosphorylation
86
Q

What is produced per round of beta oxidation?

A
  • 1 FADH2
  • 1 NADH
  • 1 Acetyl CoA
  • 1 Acyl CoA shortened by 2 Cs
87
Q

What is required for fatty acid synthesis?

A

NADPH

88
Q

What happens in fatty acid synthesis?

A

Sequential addition of 2 C from acetyl CoA

89
Q

What is the enzyme used in fatty acid synthesis?

A

fatty acid synthase

90
Q

__________ are not stored in the body or excreted, they are turned into fuel

A

proteins

91
Q

What is the a-amino group converted to in protein metabolism?

A

urea

92
Q

What is the Carbon skeleton converted to in protein metabolism?

A

metabolic intermediate (acetyl CoA, pyruvate, TCA intermediate)

93
Q

What is the site of protein degredation?

A

Liver

94
Q

What is the first step of protein degradation?

A

removal of nitrogen

(a-amino group transferred to a-ketoglutarate to form glutamate and ammonium ion)

95
Q

What is the second step of protein degradation?

A

Carbon skeleton metabolized

96
Q

Transamination and deamination of amino acids produces ____________________

A

ammonium ion

97
Q

Urea cycle functions to

A

Eliminate excess nitrogen

98
Q

Where does the urea cycle start

A

In mitochondria

99
Q

The urea cycle occurs almost exclusively in the _______

A

Liver

100
Q

urea formed in the liver passes via bloodstream to ___________ and is then excreted in urine

A

Kidneys

101
Q

What is pyruvate converted into

A

Acetyl CoA

102
Q

Where is pyruvate transported to

A

Mitochondria

103
Q

Is the conversion of pyruvate to acetyl CoA reversible?

A

No, essentially irreversible

104
Q

What does the conversion of pyruvate to acetyl CoA produce?

A

CO2 and NADH

105
Q

What is the size of the pyruvate dehydrogenase complex?

A

4,000-10,000 kDa- Huge!!

106
Q

What is the prosthetic group of pyruvate dehydrogenase complex?

A

thiamin pyrophosphate (TTP)
Active form of thiamin (B1)

107
Q

Is the inactive form of pyruvate dehydrogenase phosphorylated or not?

A

Yes it is

108
Q

What directly inhibits pyruvate dehydrogenase?

A
  • NADH
  • acetyl CoA
  • ATP
109
Q

What stimulates pyruvate dehydrogenase?

A

Pyruvate; ADP indirectly

110
Q

Key irreversible step in the metabolism of glucose that uses pyruvate dehydrogenase

A

Pyruvate into acetyl CoA

111
Q

Acetyl CoA is end product of:

A
  • glycolysis via pyruvate
  • fatty acid oxidation
  • amino acid degradation
  • TCA intermediates
112
Q

The citric acid cycle, or Krebs cycle, Harvests electrons from what?

A

Carbon fuels (acetyl group)

113
Q

The krebs cycle provides precursors to what?

A
  • amino acids
  • nucleotide bases
  • oxaloacetate (to make glucose)
114
Q

Where does the Krebs cycle take place?

A

Mitochondria

115
Q

Oxaloacetate (C4) + acetyl unit (C2) = ?

A

tricarboxylic acid (C6)

116
Q

the krebs cycle regenerates what?

A

Oxaloacetate

117
Q

What is produced in the Krebs cycle?

A

carbon dioxide, NADH, FADH2

118
Q

What is lost in the krebs cycle as CO2?

A

acetyl group

119
Q

Does the Krebs cycle require oxygen?

A

No

120
Q

What catalyzes the condensation of acetyl CoA and Oxaloacetate?

A

citrate synthase - pace setting enzyme

(irreversible reaction)

121
Q

What enzymes are the key control points of the Kreb’s cycle?

A
  • isocitrate dehydrogenase
  • α-ketoglutarate dehydrogenase.
122
Q

The concentration of ATP and NADH can regulate what cycle?

A

Kreb’s cycle

123
Q

High citrate concentration inhibits what?

A

Citrate synthase

124
Q

Isocitrate dehydrogenase is inhibited by what?

A

NADH, ATP

125
Q

Isocitrate dehydrogenase is stimulated by what?

A

ADP

126
Q

a-ketoglutarate dehydrogenase
is inhibited by what?

A

succinyl coenzyme A (competes for CoA)

127
Q

The electron transport chain is a series of electron carriers where?

A

Inner mitochondrial membrane

128
Q

In the ETC, electrons are passed from NADH and FADH2 to O2 to form ______________

A

Water

129
Q

In the ETC, electrons are passed from NADH and FADH2 to O2 to form ______________

A

Large decrease

130
Q

free energy is captured in what form in the electron transport chain?

A

hydrogen ion (proton) gradient and voltage gradient across inner membrane

131
Q

proton-motive force drives _______ synthesis

A

ATP

132
Q

Where are uncoupling proteins found?

A

Inner mitochondrial membrane

133
Q

What do uncoupling proteins do?

A
  • reduce ATP synthesis
  • dissipate proton motor force
134
Q

What is well developed in brown adipose tissue in small mammals and in newborns?

A

uncoupling proteins

135
Q

What increases due to uncoupling proteins?

A
  • glucose oxidation
  • heat production
    (ATP levels no longer inhibiting)
136
Q

What activates uncoupling proteins?

A

thyroid hormones

DEN 7101F - Human Structure and Function (23 decks)

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