Biochemistry Final Exam 1 Flashcards
1
Q
What 2 enzymes are the connection between glucose transport?
A
hexokinase and glucose-6-phosphatase
2
Q
What kind of tissue/cell type is GLUT1 transporter present in?
A
most tissue/cells
3
Q
What kind of tissue/cell type is GLUT3 transporter present in?
A
neuronal tissue/cells
4
Q
What kind of tissue/cell type is GLUT2 transporter present in?
A
hepatocytes
pancreatic B cells
5
Q
What kind of tissue/cell type is GLUT4 transporter present in?
A
skeletal myocytes
cardiomyocytes
adipocytes
6
Q
What GLUT transporter is glucose sensitive?
A
GLUT2
7
Q
What GLUT transporters are always near max rate regardless of [glucose]?
A
GLUT 1
GLUT 3
8
Q
What GLUT transporter is insulin dependent?
A
GLUT4
9
Q
When [insulin] increases, what happens to GLUT4?
A
GLUT4 vesicles fuse with cell membrane and access blood for insulin transport
10
Q
When [insulin] decreases, what happens to GLUT4?
A
GLUT4 are sequestered into cell via vesicles
11
Q
What is the appropriate glucose transporter for cells charged with blood glucose regulation?
A
one that is sensitive to changes in [glucose]
12
Q
If glucose is modified (phosphorylation) after entering a cell, what happens to net transport?
A
remain favorable
13
Q
What enzyme is involved in the commitment step in metabolism?
A
hexokinase
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
15
Q
Where is hexokinase I-III found?
A
most cell types
16
Q
Hexokinase I-III are similar to which GLUTs and why?
A
GLUT 1 and 3
insensitive to [glucose]
always at max rate
17
Q
What is hexokinase I-III inhibited by?
A
glucose-6-phosphatase
18
Q
What GLUTs are used by hexokinase I-III?
A
GLUT 1
GLUT 3
19
Q
What is another name for hexokinase IV?
A
glucose kinase
20
Q
hexokinase IV is an _________ enzyme
A
allosteric enzyme
21
Q
Hexokinase shows a ________ response to [glucose] which is S shaped on a plot
A
sigmoid response
22
Q
is Hexokinase IV sensitive to [glucose]?
A
Yes
23
Q
Is hexokinase IV inhibited by glucose-6-phosphatase like hexokinase I-III?
A
no
24
Q
What cells is hexokinase IV present in?
A
hepatocytes
pancreatic B cells
25
Insulin signaling ___________ Hexokinase IV expression
increases
26
glucagon signaling ___________ hexokinase IV expression
decreases
27
Hepatocytes also produce glucokinase regulatory proteins (GKRP). How is it involved with hexokinase IV?
glucose and GKRP compete for hexokinase IV
28
Increased [glucose] = increased Hexokinase IV which is active where?
cytosol
29
decreased [glucose] = increased Hexokinase IV which is inactive where?
nucleus
30
What enzyme completes gluconeogenisis?
glucose-6-phosphatase
31
What cell type is glucose-6-phosphatase mainly found in?
heptatocytes
32
How does glucose-6-phosphatase allow glucose to cross membrane?
removes phosphate so glucose can cross membrane using GLUT2
33
What are the 2 types of control in glucose-6-phosphatase?
substrate level control
transcriptional level control
34
What is an example of substrate level control using glucose-6-phosphatase?
increased [G-6-P] = increased rate
35
What is an example of transcriptional level control using glucose-6-phosphatase?
increased glucagon = increased expression of G-6-P
36
Allosteric enzymes DO NOT follow Michelins-Menten Kinetics, it as a ____________ response
sigmodial response
37
Sigmodial response in allosteric enzymes [substrate] indicates _______________
positive cooperativity
38
What is positive cooperatively?
binding os substrate at one active site enhances binding at another active site
39
What are the 2 different symmetry models for positive cooperativity?
T -- tight
R -- relaxed
40
Which conformation of the symmetry model interacts poorly with the substrate?
T -- tight
41
Can an enzyme have both conformations of the symmetry model?
no; not both
42
Which conformation of the symmetry model interacts well with the substrate?
R -- relaxed
43
T/F? According to the symmetry model of allosteric enzymes, [T]/[R] is a large positive number
true
44
is the disassociation constant of the T conformation of the symmetry model large or smaller than R?
smaller because it interacts well with substrate
45
Allosteric _______ increase the cooperativity affect
increases
46
On a plot for the coopereativity affect, where is the line for an allosteric inhibitor is present and when an allosteric activator is present?
activator -- on top
inhibitor -- on botton
47
When an allosteric inhibitor is present, why is more [substrate] required?
more [s] is needed to overcome bias which will increased the cooperativity affect (get up the hill)
48
Allosteric activators prefer the R or T state?
R -- relaxed
49
Do allosteric inhibitors increase/decrease the cooperativity affect?
decrease
50
For the enzyme phosphofructokinse-1, Glu goes the the ____ active site and Arg goes to the ____ active site
Glu -- T
Arg -- R
51
ATP is an allosteric inhibitor or activator?
BOTH
52
What is a major regulator enzyme of glycolysis/gluconeogensis?
F-2,6-BP
53
PFK-2/FBPase-2 is regulated by _____________ modification
covalent modification (phos/dephos)
54
Does insulin activate or inactivate PKA?
inactivate
55
Does insulin activate or inactivate PPP-1?
activate
56
increased insulin = fasting or well fed?
well fed
57
increased glucagon = fasting or well fed?
fasting
58
insulin present...
increase/decrease F-2,6-BP
increase/decrease PFK-1
increase/decrease FBPase
increase/decrease glycolysis
increase/decrease gluconeogensis
increase F-2,6-BP
increase PFK-1
decrease FBPase
increase glycolysis
decrease gluconeogensis
59
Does glucagon activate or inactivate PKA?
activate
60
Does glucagon activate or inactivate PPP-1?
inactivate
61
Epinepherine has the same response in cardiomyocytes as _________ has in hepatocytes
glucagon
62
gluconeogensis does not happen in ________cytes
cardiomyoctes
63
Epinephrine presence __________ PKA and ________ PPP-1
activates PKA
inactivates PPP-1
64
In the well fed state, insulin signaling __________ AKT (protein kinase B)
activates
65
Pyruvate kinase is regulated by _____________ modification
covalent modification (phos/dephos)
66
For pyruvate kinase deactivation, KD for ATP is high or low?
high
67
For pyruvate kinase activation, KD for ATP is high or low?
low
68
glucagon/epinepherine __________ PKA
activates
69
glucagon/epinepherine ___________ PPP-1
inactivates
70
insulin ____________ PKA
inactivates
71
insulin ____________ PPP-1
activates
72
What enzyme in gluconeogenisis is biotin dependent?
pyruvate carboxylase
73
Pyruvate carboxylase is inactive without ____________
acetyl coA
74
In the well fed state PEPCK increases/decreases?
decreases
75
In the fasting state PEPCK increases/decreases?
increases
76
What hexokinase is used in glycogensis?
HK IV
77
In glycogenisis, UDP glucose requires inorganic ______________
pyrophosphatase
78
What is UDP-glucose?
active form of glucose
79
what is the branching enzyme in glycogenesis?
glycogen synthase
80
when glucose is debranched, what happens to its solubility?
increases solubility
81
what linkage does the branching enzyme create for glucose?
alpha-1,4 linkage
82
What is the advantages of branching glucose for glycogenisis?
helps it fit into hepatocytes
allows more places to phosphorylate
83
What is the purpose of glycogenlysis?
glycogen previously stored by the liver is broken down to glucose and dispersed throughout the body (body needes energy)
84
what is the purpose of glycogenisis?
storing excess glucose for use by the body at a later time
85
All the steps in dietary starch digestion are __________
hydrolytic
86
In dietary starch digestion, alpha-amylase hydrolyzes alpha-________-glycosidic bond
alpha-1,4-glycosidic bond
87
In dietary starch digestion, alpha 1,6-glucosidase remove the _________ point
branch point
88
In dietary starch digestion, alpha-1,4-gluconotransferase removes the ___________ branch
limit branch
89
what is the debranching enzyme in glycogenolysis?
alpha-1,6,glucosidse
90
what order does the debranching enzyme remove the linkages?
alpha-1,4-glycosidc then alpha-1,6
91
when talking about glycogen, more phosphorylation means more or less activity?
less activity
92
in glycogenisis, when glycogen synthase is phosphorylated, is it activated or deactivated?
inactivate
93
is glycogen phosphorylase a or b the more active form?
a
94
is glycogen phosphorylase a or b sensitive to internal conditions?
a
95
is glycogen phosphorylase a or b apart of the fight/flight response?
a
96
is phosphorylase kinase activated or inhibited by PKA?
activated
97
is phosphorylase kinase activated or inhibited by Ca2+?
activated
98
in glycogenolysis, is PPP-1 activated or inhibited by insulin?
activated
99
in glycogenolysis, is PPP-1 activated or inhibited by epinephrine and glucagon?
inhibited
100
is PPP-1 or PKA involved in the fight or flight response for glycogen?
PKA
101
What is the only hydrolytic step in glycogenlysis?
alpha-1,6-glucosidase
102
T/F? Alanine increases positive cooperatively in pyruvate kinase activity
true
103
T/F? hexokinase catalyzes the commitment step to glycolysis
false
104
T/F? pyruvate kinase in adipocytes is regulated by phosphorylation/dephosphorylation
false
105
T/F? glycogen store in hepatocytes can be used as a source of glucose to sustain red blood cells during fasting
true
106
T/F? glucose-6-phosphatase is an enzyme only found in cardiomyocytese
false
107
T/F? glycogen stored in skeletal muscle cells is broken down primarily by hydrolysis reactions
false
108
T/F? glycogen phosphorylase uses inorganic phosphate as a phosphoryl donor
true
109
What is the delta G for pyruvate carboxylase?
negative
110
What is the delta G for phosphoglucomutase?
0
111
What is the delta G for fructose-1,6,bisphosphatase?
negative
112
What is the delta G for UDP-glucose pyrophosphorylase?
0
113
is pyruvate kinase inhibited or activated by being phosphorylated?
inhibited
114
What are some kinases involved in muscle contraction?
Ca2+ / calmodium
PKA
phosphorylase kinase
PFK-1
115
What kinases will increase in activity if epinephrine is present?
Ca2+ / calmodium
PKA
phosphorylase kinase
116
What is the substrate for glycogenin?
UDP-glucose
117
When insulin is signaling, what happens to phosphorylase kinase activity?
increases
118
When insulin is signaling, what happens to glycogen synthase kinase activity?
decreased
119
What is the role of glycogenin in glycogen metabolism?
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
Suppose cardiomyocytes are stimulated by epinetherine; PKA activity will increase or decrease?
increase
121
Suppose cardiomyocytes are stimulated by epinetherine; pyruvate kinase activity will be phosphorylated or dephosphorylated?
dephosphorylated
122
Suppose cardiomyocytes are stimulated by epinetherine; PFK-2/FBPase-2 will be phosphorylated or dephosphorylated?
phosphorylated
123
Suppose cardiomyocytes are stimulated by epinetherine; the concentration of F-2,6-BP will increase or decrease?
increase
124
If there is too much PFK-2 and not enough FBPase-2 what will happen to glucose metabolism?
glycolysis will be unregulated
125
What happen if pyruvate kinase cannot be phosphorylated in glucose metabolsim?
glycolysis will be unregulated
126
if glycolysis is inhibited what happens to glucose uptake?
glucose uptake would decrease
127
If PFK-1 is inhibited what happens to glucose uptake?
F-6-P and G-6-P would accumulate and are inhibitors of HK I-III so glucose accumulates and transport stops
128
In cardio
