Exam 2 11/3 Howard Flashcards
(136 cards)
1
Q
Glycogenolysis
A
Glycogen breakdown
2
Q
Glycogenesis
A
Glycogen synthesis
3
Q
Glycogen metabolism is highly ___ and needs to respond to ____
A
regulated; hormones and metabolites
4
Q
Where are glycogen reducing ends found
A
In a circle all around the glycogen molecule
5
Q
If glycogenolysis is on, glycogenesis should be
A
Off (and vice versa)
6
Q
Where is glycogen mainly found
A
Muscle and liver
7
Q
Free anomeric carbon is
A
Reducing end
8
Q
Why does the liver store glycogen
A
Needs to be able to maintain blood glucose between meals
9
Q
Muscle stores glycogen for:
A
Its own energy needs
10
Q
3 steps of glycogen breakdown
A
- release of G1P
- Remodeling of glycogen
- Formation of G6P
11
Q
Fate of G6P
A
- fuel for ATP generation
- converted into glucose3
- PPP to generate NADPH or ribose
12
Q
Glycogen degradation occurs at
A
Non-reducing end
13
Q
Enzyme used to break down glycogen
A
Glycogen phosphorylase
14
Q
Glycogen phosphorylase breaks down glycogen by ____ to form what molecule?
A
Phosphorylytic cleavage; G1P
15
Q
In order to perform phosphorolytic cleavage of glycogen, it must use what phosporyl source?
A
Direct phosphoryl group donation (not from ATP!!)
16
Q
Pyridoxal phosphate (PLP) is a derivative of
A
Pyridoxine (vitamin B6)
17
Q
____ requires Pyridoxal phosphate (PLP)
A
Glycogen phosphorylase
18
Q
Where does glycogen phosphorylase stop?
A
4 residues away from a branch point
19
Q
Transferase
A
Shifts a block of three glycosyl residues
20
Q
alpha 1,6 glucosidase
A
Hydrolyzes alpha 1,6 glycosidic bond (now is just a lone glucose molecule
21
Q
In eukaryotes, _____ and ____ is a single bifunctional enzyme during glycogen debranching
A
transferase, alpha 1,6-glucosidase
22
Q
Phosphoglucomutase converts ____ into ____
A
G1P to G6P
23
Q
Glycogen phosphorylase is a ____ (structure)
A
dimer
24
Q
Glycogen phosphorylase - allosteric _____
A
Energy state
25
Glycogen phosphorylase undergoes ______ in response to hormonal signals
reversible phosphorylation
26
Which phosphorylase state is phosphorylated and where?
Phosphorylase a; at a serine 14 reside in each subunit
27
What phosphorylates Glycogen phosphorylase
phosphorylase kinase
28
Phosphorylase a favors
R state
29
Phosphorylase b favors
T state (taut)
30
Glycogen phosphorylase has _____ specificity
Tissue
31
Phosphorylase b is found in
Muscle
32
In muscle, a low energy charge (represented by _____) favors the transition to _____
high conc of AMP; R state
33
What can increase epinephrine
fear or excitement of exercise
34
If epinephrine is increased (a ____ response), _____ phosphorylates to _____ form
hormonal; muscle phosphorylase; phosphorylase a
35
Phosphorylase a is found in
Liver
36
In liver phosphorylase, when glucose is already abundant, _____ is not mobilized because _____ shifts the equilibrium to the ___ state which inactivates the enzyme
glycogen; glucose; T
37
Glycogen synthesis is done by what enzyme
glycogen synthase
38
____ is reciprocally regulated
Glycogen synthesis
39
UDP glucose is
An activated form of glucose (activated glucose donor)
40
How is UDP glucose made (enzyme and starting substrate)
Enzyme - UDP-glucose pyrophosphorylase
Starts from G1P
41
Phosphoglucomutase converts G1P into
G6P
42
_____ catalyzes transfer of glucose from UDP-glucose
Glycogen synthase
43
Glycogen has ____ reducing end(s) and ___ non-reducing end(s)
1 reducing, 2 non-reducing
44
phosphorylase a is usually ___________
active
45
phosphorylase b is usually _________________
inactive
46
phosphorylase a favors the ____ state
R state (relaxed)
47
phosphorylase b favors the ____ state
T state (taut)
48
A low energy charge, represented by high concentrations of AMP, favors the transition to the ___ state (more active) of muscle phosphorylase
R state
49
Fear or the excitement of exercise increases epinephrine: phosphorylates to Phosphorylase ____ form: hormonal response (in muscles)
A form (active)
50
Branching increases the _____________ of glycogen; inc. rate of synthesis and degradation
Solubulity
51
Is glycogen synthase a phosphorylated? Is it active or inactive?
NOT phosphorylated, active
52
Is glycogen synthase b phosphorylated? Is it active or inactive?
phosphorylated, NOT active
53
Is phosphorylase a phosphorylated? Is it active or inactive?
phosphorylated, active
54
Is phosphorylase b phosphorylated? Is it active or inactive?
NOT phosphorylated, NOT active
55
The Pentose Phosphate Pathway is also called.....
- Phosphogluconate pathway
- Hexose monophosphate shunt
56
The Pentose Phosphate Pathway is a major source of ____________ for reductive biosynthesis
NADPH
57
What pathway provides Ribose for RNA, DNA, ATP, NADH, FAD, and CoEnzyme A synthesis?
Pentose Phosphate Pathway
58
The enzymes involved in the pentose phosphate pathway are ____________ enzymes
Cytoplasmic
59
Does the pentose phosphate pathway consume or produce ATP?
NO
60
The oxidative phase of the pentose phosphate pathway generates what?
NADPH
61
The nonoxidative phase of the pentose phosphate pathway interconverts _______________
Phosphorylated sugars
62
True or False: the two phases of the pentose phosphate pathway can function together or independently depending on metabolic needs
True
63
What controls the rate of the pentose phosphate pathway?
Level of NADP+
64
Flow of __________________ depends on the Need for NADPH, ribose 5-phosphate, and ATP (pentose phosphate pathway)
G6P
65
If much more ribose 5-phosphate is needed than NADPH: ribose 5-phosphate is made ______________ NADPH synthesis (Mode 1 pentose phosphate)
Without
66
If need for NADPH and ribose 5-phosphate is equal, then _____________ are made (Mode 2 pentose phosphate)
Both
67
If much more ___________ is needed (Mode 3 pentose phosphate)
NADPH
68
IF both NADPH and _____ is needed (Mode 4 pentose phosphate)
ATP
69
What are sources of triglycerides?
- Diet
- Synthesis and storage
70
Where are triglycerides found in the cell?
Cytosol of adipose cells; muscle
71
What are efficient energy stores that are:
-Reduced
-Anhydrous
Triglycerides
72
triglycerides are broken into what by hormone sensitive lipases?
Glycerol and free fatty acids (and albumin)
73
What are the "fates" of triglyceride?
1. glycerol goes to glycolysis/gluconeogenesis (in liver)
2. fatty acids (ffa) go to fatty acid oxidation
74
Glycerol is absorbed into the liver and converted into what intermediate of glycolysis/gluconeogenesis?
glyceraldehyde 3-phosphate
75
What is the first stage of fatty acid oxidation?
ffa converted to fatty acyl CoA
76
What is the 2nd stage of fatty acid oxidation?
b-oxidation and Acetyl CoA production
77
What is the 3rd stage of fatty acid oxidation? (after TCA cycle)
Electron transport to generate a proton-motive force
78
What is the 4th stage of fatty acid oxidation? (after TCA cycle)
ATP synthesis
79
What is the 4th stage of fatty acid oxidation? (after TCA cycle)
ATP synthesis
80
Fatty acids use _____ to bind to CoA and form Acyl CoA
ATP (forms thioester linkage)
81
Where does the reaction between fatty acids and CoA occur?
Outer mitochondrial membrane
82
How do acyl groups enter mitochondria?
- Fatty acid conjugated to carnitine
- Translocase exchanges acyl carnitine for carnitine
- Re-form Acyl CoA in mito matrix
83
Where does beta oxidation occur?
mitochondria
84
beta oxidation of fatty acids is a repetition of sequence of ____ reactions
4
85
What happens in beta oxidation of fatty acids?
- Acetyl CoA enters TCA
- NADH and FADH2 carry electrons to oxidative phosphorylation
86
What is produced per round of beta oxidation?
- 1 FADH2
- 1 NADH
- 1 Acetyl CoA
- 1 Acyl CoA shortened by 2 Cs
87
What is required for fatty acid synthesis?
NADPH
88
What happens in fatty acid synthesis?
Sequential addition of 2 C from acetyl CoA
89
What is the enzyme used in fatty acid synthesis?
fatty acid synthase
90
__________ are not stored in the body or excreted, they are turned into fuel
proteins
91
What is the a-amino group converted to in protein metabolism?
urea
92
What is the Carbon skeleton converted to in protein metabolism?
metabolic intermediate (acetyl CoA, pyruvate, TCA intermediate)
93
What is the site of protein degredation?
Liver
94
What is the first step of protein degradation?
removal of nitrogen
(a-amino group transferred to a-ketoglutarate to form glutamate and ammonium ion)
95
What is the second step of protein degradation?
Carbon skeleton metabolized
96
Transamination and deamination of amino acids produces ____________________
ammonium ion
97
Urea cycle functions to
Eliminate excess nitrogen
98
Where does the urea cycle start
In mitochondria
99
The urea cycle occurs almost exclusively in the _______
Liver
100
urea formed in the liver passes via bloodstream to ___________ and is then excreted in urine
Kidneys
101
What is pyruvate converted into
Acetyl CoA
102
Where is pyruvate transported to
Mitochondria
103
Is the conversion of pyruvate to acetyl CoA reversible?
No, essentially irreversible
104
What does the conversion of pyruvate to acetyl CoA produce?
CO2 and NADH
105
What is the size of the pyruvate dehydrogenase complex?
4,000-10,000 kDa- Huge!!
106
What is the prosthetic group of pyruvate dehydrogenase complex?
thiamin pyrophosphate (TTP)
Active form of thiamin (B1)
107
Is the inactive form of pyruvate dehydrogenase phosphorylated or not?
Yes it is
108
What directly inhibits pyruvate dehydrogenase?
- NADH
- acetyl CoA
- ATP
109
What stimulates pyruvate dehydrogenase?
Pyruvate; ADP indirectly
110
Key irreversible step in the metabolism of glucose that uses pyruvate dehydrogenase
Pyruvate into acetyl CoA
111
Acetyl CoA is end product of:
- glycolysis via pyruvate
- fatty acid oxidation
- amino acid degradation
- TCA intermediates
112
The citric acid cycle, or Krebs cycle, Harvests electrons from what?
Carbon fuels (acetyl group)
113
The krebs cycle provides precursors to what?
- amino acids
- nucleotide bases
- oxaloacetate (to make glucose)
114
Where does the Krebs cycle take place?
Mitochondria
115
Oxaloacetate (C4) + acetyl unit (C2) = ?
tricarboxylic acid (C6)
116
the krebs cycle regenerates what?
Oxaloacetate
117
What is produced in the Krebs cycle?
carbon dioxide, NADH, FADH2
118
What is lost in the krebs cycle as CO2?
acetyl group
119
Does the Krebs cycle require oxygen?
No
120
What catalyzes the condensation of acetyl CoA and Oxaloacetate?
citrate synthase - pace setting enzyme
(irreversible reaction)
121
What enzymes are the key control points of the Kreb's cycle?
- isocitrate dehydrogenase
- α-ketoglutarate dehydrogenase.
122
The concentration of ATP and NADH can regulate what cycle?
Kreb's cycle
123
High citrate concentration inhibits what?
Citrate synthase
124
Isocitrate dehydrogenase is inhibited by what?
NADH, ATP
125
Isocitrate dehydrogenase is stimulated by what?
ADP
126
a-ketoglutarate dehydrogenase
is inhibited by what?
succinyl coenzyme A (competes for CoA)
127
The electron transport chain is a series of electron carriers where?
Inner mitochondrial membrane
128
In the ETC, electrons are passed from NADH and FADH2 to O2 to form ______________
Water
129
In the ETC, electrons are passed from NADH and FADH2 to O2 to form ______________
Large decrease
130
free energy is captured in what form in the electron transport chain?
hydrogen ion (proton) gradient and voltage gradient across inner membrane
131
proton-motive force drives _______ synthesis
ATP
132
Where are uncoupling proteins found?
Inner mitochondrial membrane
133
What do uncoupling proteins do?
- reduce ATP synthesis
- dissipate proton motor force
134
What is well developed in brown adipose tissue in small mammals and in newborns?
uncoupling proteins
135
What increases due to uncoupling proteins?
- glucose oxidation
- heat production
(ATP levels no longer inhibiting)
136
What activates uncoupling proteins?
thyroid hormones
