EXAM 1 Flashcards
(182 cards)
1
Q
what are the four functions of metabolism
A
- obtain free energy for the cell
- degrade macromolecules as required for biological function
- convert nutrients into macromolecules
- assemble macromolecules into cellular structures
2
Q
T/F metabolism does not require tightly coordinated cellular activity
A
F, it does require
3
Q
T/F living organisms need a continuous influx of energy to battle entropy
A
T
4
Q
what is known as the sum of all of the chemical reactions occuring in the cell
A
Metabolism
5
Q
define metabolism
A
the overall processes by which living things acquire and utilize free energy in the cell
6
Q
what are the basic units of metabolism
A
enzymes
7
Q
substrates of the enzymes of metabolism are called
A
metabolites
8
Q
define metabolic pathway
A
a series of connected enzymatic reactions that produces a specific product
9
Q
T/F metabolic pathways consist of sequential steps
A
T
10
Q
two compartments of metabolism
A
catabolism and anabolism
11
Q
define catabolism
A
degradative pathways the produce free energy
12
Q
define anabolism
A
biosynthetic pathways that consume free energy
13
Q
In a catabolic pathway the electrons energy-yielding nutrients lost are stored in…
A
NADH
FADH2
NADPH
14
Q
List the energy-yielding nutrients that are used in catabolism
A
Cabrohydrates
Fats
Proteins
15
Q
In an anabolic pathway, where do you get the energy you need to proceed the reaction
A
NADPH
16
Q
List the cell macromolecules of anabolic pathways
A
Proteins
Polysaccharides
Lipids
Nucleic Acids
16
Q
List the precursor molecules in anabolic pathway
A
Amino Acids
Sugars
Fatty Acids
Nitrogenous bases
17
Q
ATP hydrolysis is important for
A
biosynthesis
osmotic work
cell motility/muscle contraction
18
Q
Energy-requiring cellular activities are powered by ATP hydrolysis, liberating what as products
A
ADP and Pi
19
Q
In energy requiring cellular activities are powered by
A
ATP hydrolysis
20
Q
Why is ATP a high energy compound?
A
hydrolysis increased resonance stabilization which allows for shifting of bonds
hydrolysis decreased electrostatic interactions
hydrolysis increased energy of solvation/entropy
21
Q
what is the reaction that occurs between NAD+ and NADH ?
A
dehydrogenase reaction
22
Q
what is the most common e- carrier that always transfer two e- at a time
A
NADH
23
Q
What is NADH used in? What about NADPH?
A
NADH used in fuel metabolism , mobile e- carrier for ETC/PMF/ATP synthesis, catabolism
NADPH used for biosynthesis, anabolism
24
Compartmentalization
Metabolic pathways are localized within different cellular compartments/locations
25
T/F anabolic and catabolic pathways involving same product are not the same
T
26
T/F some steps may be common to both anabolic and catabolic pathways
T
27
what ensures that each pathway is spontaneous/thermodynamically favorable
unique enzymes
28
define biosynthetic enzymes
operate as part of anabolic pathways
29
define degradative enzymes
operate as part of catabolic pathway
30
water-solube vitamins almost always ......
converted to coenzymes
31
T/F Fat soluble vitamins are stored for longer periods of time
T
32
how are metabolic pathways controlled?
Thermodynamics
compartmentalization
metabolic flux
33
how can metabolic flux be controled
allosteric
covalent modification
substrate cycles
genetic control
34
T/F ATP does not need to be biosynthesized
F, it must be biosynthesized
35
ATP/equivalent molecules are used to....
power endergonic processes
36
glycolysis is divided into 2 phases what are they
investment phase
payoff phase
37
define glycogen
multi-branched polysaccharide of glucose
38
where does glycogen fit into metabolic picture
degraded when glucose is needed ( low energy status)
synthesized for energy storage ( high energy status)
39
define glycolysis
pathway for glucose breakdown that consists of 10 enzymes that make end product pyruvate
40
define PPP
alternative pathways that allows for NADPH production and provides biosynthetic precursors
41
define GNG
pathway in liver and kidneys that allows for the production of glucose from pyruvate, lactate and amino acids
42
where does glycolysis occur
in cytoplasm
43
T/F glycolysis is anaerobic
T
44
the first phase of glycolysis converts glucose to
2 glyceraldehyde-3-phosphate at the expense of 2 ATP
45
second phase of glycolysis produces
2 pyruvate
2 ATP YIELD
2 NADH
46
List all substrate and enzymes along with biproducts in glycolysis in order
1. Glucose
ATP -> ADP || Hexokinase/glucokinase
2. Glucose 6 Phosphate
|| Phosphoglucoisomerase
3. Fructose 6 Phosphate
ATP --> ADP || Phosphofructokinase
4. Fructose - 1,6 - bisphosphate
|| aldolase
5. Dihydroxyacetone phosphate + Glyceraldehyde 3 phosphate
( Triose phosphate isomerase)
NAD+ --> NADH||Glyceraldehyde-3-Phosphate DH
6. 1,3- Bisphosphoglycerate
ATP --> ADP || Phosphoglycerate kinase
7. 3 phosphoglycerate
|| Phosphoglycerate mutase
8. 2-phosphoglycerate
release H2O || enolase
9. phosphoenol pyruvate
ADP --> ATP || pyruvate kinase
10. Pyruvate
47
lactate DH function
reduces pyruvate to lactate using NADH
reversible
cori cycle
48
TPP defecincy causes
beriberi disease
49
symptoms of TPP deficiency
Pain
Paralysis
wasting
heart failure
50
pyruvate decarboxylase requires
thiamine pyrophosphate (TPP)
51
the making of glucose from non-carbohydrate precursor is what pathways
GNG
52
GNG meets body's glucose needs under
fasting conditions
53
GLUT 2
low affinity transporter in hepatocytes (liver) and pancreatic cells
54
GLUT 4
higher affinity transporter in adipose tissue and muscle cells
55
why is it important for GLUT 4 to have higher affinity for glucose than GLUT 2
liver is able to make its own glucose so we want to give other cells such as the muscle and adipose tissue to have first dibs to get the sugar they need
56
what glucose transporter serves as sensor for insulin release
GLUT 2
57
compare and contrast GLUT 2 and GLUT 4 in terms of Km and kinetics
GLUT 4 has a low Km and 0th order kinetics
GLUT 2 has high Km and 1st order kinetics
58
how does insulin promote glucose entry into cells
allows for increased production of GLUT4 through vesicle fusion
59
T/F glycolysis does not use oxidative phosphorylation it is a substrate level phosphorylation reaction
T
60
what is the enzyme used for the priming reaction in glycolysis
hexokinase/glucokinase
61
compare hexokinase and glucokinase
HK
- present in muscle and most tissues
- low Km
GK
- present in the liver and pancrea ( b-islet cells)
62
how is Hexokinase regulated
inhibited by high levels of glucose-6-phosphate
Insulin activates
glucagon inhibits
63
how is glucokinase hormonally regulated
induced by insulin in liver
64
why do we have two different enzymes (HK/GK) for the conversion of glucose to G6P?
it makes sure that all other cells like muscles can get what they need and THEN the liver will deal with the leftover glucose and store it
65
what are other fates of glucose-6-phosphate other than glycolysis ?
1. PPP to make NADPH
2. Glycogen
3. carbohydrate synthesis
66
describe the mechanism of HK and GK
glucose does nucleophilic attack in P group of ATP causing an induced fit releasing ADP and leaving a P group attached
67
what enzyme forms glucose-6-phosphate from glucose
HK/GK
68
Phosphoglucose isomerase function
reconfigures bonds to form F6P
69
T/F Phosphoglucose isomerase has a small value of free energy change indicating that the reaction is near equilibrium and is therefore a regulated step
F, it is reversible enzyme due to the small value in free energy change
70
why does the reaction of phosphoglucosisomerase occur
- b/c next step is a second phosphorylation and a hemiacetal is a tougher reaction compared to Primary -OH
- puts carbonyl at C2 which activates C3 for an aldolytic cleavage
71
what enzymes of glycolysis has an enediol intermediate
Phosphoglucoisomerase
Triose Phosphate Isomerase
72
what kind of reaction is PGI
acid-base catalysis
73
what are the irreversible enzymes of glycolysis
GK/HK
PFK1
Pyruvate Kinase
74
what is the enzyme known as the first committed step of glycolysis
PFK1
75
How is PFK1 regulated
High levels of AMP activate it
High levels of ATP and Citrate inhibit
76
when will we see PFK activity increase and decrease
increase: lw energy status
decrease: high energy status
77
how is PFK allosterically regulated
Fructose-2,6-bisphosphate and AMP : activates PFK1
citrate and atp inhibit
78
How is PFK1 hormonally regulated
High levels of insulin = activate
High levels of glucagon = inhibit
79
how does insulin activate PFK1
it activates PFK2 which converts F6P to F26BP , a potent allosteric activator, which in turn activates PFK1
80
How does glucagon inhibit PFK1
glucagon inhibits PFK2, and stimulates F26BPase of GNG inhibiting PFK1
81
function of aldolase in glycolysis
cleavage step, beaks F16BP into 2 3C units, DHAP and GA3P
82
There are 2 classes of aldolase enzymes, compare the two types
Class I Aldolase:
- found in animal tissues
- formation of covalent Schiff-Base E-S intermediate
Class II Aldolase:
- contain. an active site metal (ZN2+) to help shield the oxyanion intermediate
83
function of Triose Phosphate Isomerase
undergoes isomerization reaction that is reversible interconvert b/w DHAP and GA3P
84
what type of chemistry is utilize in TPI
acid base
85
in TPI mechanism what amino acids function as general bases and acids
Histidine
Glutamate
86
function of glyceraldehyde 3 phosphate DH
catalyzes oxidation and addition of Pi group to GA3P forming 1,3BPG and producing NADH
87
what enzyme of glycolysis uses NAD+ as a cosubstrate that involves exchange of electrons
glyceraldehyde 3 P DH
88
characteristics of the mechanism of GA3PDH
covalent catalysis ( thioester bond formed)
nicotinamide enzyme
oxidative
89
T/F GA3PDH usess cystein residue to form thioester bond
T
90
function of phosphoglycerate kinase
transfers a P group from 1,3BPG to ADP to make ATP and form 3- Phosphoglycerate
91
what enzymes of glycolysis are referred to as substrate level phosphorylation
Pyruvate Kinase
Phosphoglycerate Kinase
92
define mutase
an enzyme that catalyzes the migration of a function group within the substrate molecules
93
What is a detour of 1,3BPG other than going straight to 3-PG that is seen in RBC
forms 2,3BPG via 1,3BPG mutase and then forms 3-PG via 2,3BPG phosphatase
94
function of 2,3BPG
regulators of Hemoglobin decreasing affinity for O2 which aids in O2 release ( R--> T state) in RBC
95
function of Phosphoglycerate mutase
catalyzes a phosphoryl group transfer from C3 to C2 forming 2-phosphoglycerate
96
what enzymes requires Mg2+ for enzymatic activity
phosphoglycerate mutase
enolase
97
what enzyme utilizes a phosphohistidyl residue
Phosphoglycerate mutase
98
function of enolase
a dehydration reaction ( loss of H2O)
forms phosphoenolpyruvate
99
function of pyruvate kinase
uses PEP as a phosphate group donor to release ATP forming pyruvate
100
How is Pyruvate Kinase Regulate
activated by high levels of AMP & F16BP
inhibited by high levels of ATP and acetyl-CoA
101
function of lactate dehydrogenase
reversible enzyme that can oxidize NADH to NAD+ ( reduce NAD+ to NADH)
Cori Cycle
102
function of DHAP other than glycolysis
used in liver and adipose tissue for TAG synthesis
103
what are the high energy intermediates of glycolysis used to generate ATP by substrate level phosphorylation
1,3BPG
PEP
104
what are the three fates of pyruvate
1. TCA cycle
2. Fermentation (yeast)
3. Lactate ( in animals)
105
what are the steps from pyruvate to form ethanol in yeast fermentation
1. pyruvate decarboxylase
2. alcohol DH
106
Pyruvate Decarboxylase characteristics
requires TPP
107
T/F high levels of lactate in muscles cause pain
T
108
where does galactose enter to glycolysis and how many enzymes are used
enters as G6P via 4 enzymes
109
where does mannose come into the glycolysis and how many enzymes
F6P via 2 enzymes
110
where does fructos (muscle) come into glycolysis and name the enzyme
F6P via HK
111
where does fructose (liver) come into glycolysis and how many enzymes
GA3P via 7 enzymes
112
what pathway uses glucose catabolism to produce NADPH
PPP
113
where does glucose synthesis occur
liver and kidneys in animals
114
list out all the steps in GNG include enzymes and biproducts and substrates
1. Pyruvate
CO2 + ATP --> ADP|| Pyruvate Carboxylase
2. OAA
GTP-->CO2 + GDP||PEP carboxykinase
3. PEP
enolase
4. 2PG
PGM
5. 3PG
ATP --> ADP || PGK
6. 1,3-BPG
NADH --> NAD+ || GA3PDH
7. GA3P <--- TPI ---> DHAP
aldolase
8. F16BP
H2O || Fructose bisphosphatase
9. F6P
PGI
10. G6P
H2O || G6Pase
Glucose
115
list the important substrates for GNG
Pyruvate
Glycerol 3 P
Lactate
Alanine/ Gluconeogenic AA
116
what are the irreversible enzymes of GNG
Pyruvate Carboxylase
PEP Carboxy Kinase
Fructose 1,6 Bisphosphatase
Glucose 6 - Phosphatase
117
What is the only enzyme of GNG found in the mitochondria
Pyruvate carboxylase
118
what is cofactor required for the mechanism of pyruvate carboxylase and its function
biotin
serves as a mobile CO2 carrier
119
how is pyruvate carboxylase regulated
high levels of acetyl CoA activate
high levels of AMP inhibit
glucagon and cortisol activate
120
describe the mechanism of pyruvate carboxylase
uses ATP to load CO2 onto biotin and then delivers it to pyruvate
121
T/F biotin contains a lys residue
T
122
what is unique about PEP carboxykinase mechanism
uses GTP rather than ATP for energy
123
why in GNG does cell add CO2 with pyruvate carboxylase and then take it back off with PEPCK?
decarboxylation drives the formation of enol that GTP phosphorylates
124
function of PEP carboxykinase
converts OAA to PEP
via GTP and decarboxylation
125
how is PEPCK regulated
activated by high levels of glucagon and cortisol
126
how is fructose 1,6 bisphosphatase regulated include hormonal
high levels of citrate and ATP activate
high levels of AMP and F26BP inhibit
cortisol , glucagon, Epi and NE activate
127
function of F16BPase
removes phosphate group from F16BP producing F6P
128
hormonal regulation of Pyruvate carboxylase
High levels of glucagon and cortisol stimulate
129
what is unique about glucose-6-phosphatase
found in the smooth ER lumen
130
function of Glucose-6-phosphatase
converts G6P to glucose by removing a P group
131
T/F all cells do GNG not just the liver and kidneys
F, it is only the liver and kidney
NOTE: Muscle and brain do not do GNG
132
if Glucose 6Pase is in the ER lumen how is it able to release glucose into blood stream
1. transporter that is concentration driven
2. uses vesicles, that are filled with glucose, and fuses with plasma membrane allowing it to open and release into bloodstream
133
what enzyme mechanism in GNG involves nucleophilic attack by a Histidine nitrogen
Glucose 6 Phosphatase
134
what enzyme contains a phosphohistidine intermediate
Glucose 6 Phosphatase
135
draw a simple sketch of cori cycle
slide 28 of GNG
136
T/F PPP can occur in all cells
T
137
what are the two functions of PPP
make NADPH and ribose-5-phosphate (imp nor nucleotide synthesis)
138
name the rate limiting enzyme of PPP
Glucose-6-phosphate DH
139
location of PPP
cytoplasm
140
define oxidative phase of PPP
use glucose metabolism to help supply NADPH for reductive reactions
141
define nonoxidative phase of PPP
use glucose metabolism to help supply ribose-5-phosphate (essential for nucleotide synthesis )
142
list the steps of the oxidative phase of PPP
1. G6P
NADP > NADPH || glucose-6-phosphate DH
2. 6phosphogluconolactone
H2O || 6Phosphogluconolactonase
3. 6 phosphogluconate
NADP > NADPH + CO2 || 6Phosphogluconate DH
4. Ribulose 5 Phosphate
143
what phase of PPP is irreversible and when is it operating
oxidative phase
on when cells need to make NADPH
144
when will PPP be turned on
highhhh ATP levels
145
functions of NADPH
biosynthetic metabolite for FA and cholesterol (electron donor )
protects against ROS ( acting as body natural antioxidant)
146
Glucose - 6- Phosphate DH regulation
High levels of NADPH inhibits
High levels of NADP+ activates
147
what metabolite is hydrolytically unstable and readily undergoes spontaneous ring opening hydrolysis
6-phosphogluconolactone
148
what enzyme of PPP serves to to accelerate the spontaneous ring opening via hydrolysis
6-phosphogluconolactonase
149
why is it important for the spontaneous ring opening in PPP to be accelerated by phosphogluconolactonase
to prevent accumulation of toxic molecule 6-phosphogluconolactone
150
what makes the mechanism of 6-phosphogluconate DH unique
has 2 phase
1. NADP+ dehydrogenation
2. decarboxylation event
151
function of phosphopentose isomerase
converts ketose to aldose
152
function of phosphopentose epimerase
changes orientation of OH group at C3 changing stereochemistry
153
Transketolase function
transfer of 2 carbon units
TPP dependent
154
transaldolase function
transfers a 3-C unit
Schiffs base mechanism
155
describe the function of Mode 1 of PPP
undergo oxidative phase because Ribose5P and NADPH is needed
156
describe function of Mode 2 of PPP
nonoxidative phase from glycolytic intermediates to produce only Ribose 5 P because it is need and No NADPH is needed
157
describe function of MODE 3 of PPP
NADPH is needed but no R5P
undergoes oxidative phase to produce NADPH and R5P
but since R5P is not needed it will feed into GNG so that it can continued to make NADPH
158
describe function of MODE 4 of PPP
ATP is needed and NADPH is needed
will undergo oxidative phase and R5P produced feeds into glycolysis at F6P , GA3P, and DHAP
159
define glycogen
multi-branch polysaccharide of glucose
stores glucose
160
where does glycogenolysis and glycogenesis occr
skeletal muscle and liver
161
what organ/tissue has a higher concentration of glycogen reservoir
Liver
162
why does the liver have higher concentration of glycogen stored
it has a role to maintain blood glucose levels at 5mM
163
what are the pros of having branch points in Glycogen
more efficient storage
allows for activity to move
164
define starch
a-linked chains of glucose in plants
165
amylase function and location
found in saliva
hydrolyzes a1-->4 glycosidic bonds of starch
166
STARCH debranching enzyme a(1-->6) glucosidase function
hydrolyzes 1 glucose residuce at a time
targets a(1-->6) bonds
167
STARCH debranching enzyme oligo (a1,4 --> a1,4)glucanotransferase function
takes a1->4 and moves it to another branch point
168
a-glucosidase function
hydrolyzes 1 glucose at a time
SOLE enzyme capable of a(1>6) glycosidic bonds
169
what enzyme leaves glycogen with one less branch point
a-glucosidase
170
function of glycogen phosphorylase
allows for breakdown of a(1.4) glycosidic bonds forming glucose-1-phosphate
171
regulation of glycogen phosphorylase in muscles
activated by high levels of AMP and Epi
inhibited by High levels of ATP & G6P
172
regulation of glycogen phosphorylase in liver
activated by glucagon
173
function of phosphoglucomutase
converts G1P to G6P
174
what enzyme is shared between glycogenolysis and Galactose metabolism
Phosphoglucomutase
175
function of glycogen synthase
forms a1,4 glycosidic bonds on linear glucose
176
how is glycogen synthase regulated
activated by insulin and high levels of G6P & ATP
inhibited by glucagon and Epi via protein kinase cascade (PKA)
177
function of UDP-glucose pyrophosphate
forms ester linkage b/w C1-OH and B-Phosphate of UDP activating glucose moiety of UDP glucose
178
what enzyme of glycogenesis occurs via an oxonium ion intermediate
glycogen synthase
179
amylo-(1,4 -> 1,6) transglycosylase function
cuts at a1,4 bond and moves it to C6 of glucose molecule forming an a1,6 glycosidic bond
180
why is glycogen metabolism linked to G1P and not G6P
G1P cant escape the cell and gives cells time to determine what is needed conversion
separates point of flux for controlling whether glycogen is synthesized or broken down
181
glucagon and Epi activate a cascade of reactions that stimulate what and inhibit what ( terms of glycogen)
glycogen breakdown
inhibit glycogen synthesis
