Chapter 17-Glycolysis Flashcards
1
Q
glycolysis
A
- breakdown of glucose (6c) to pyruvate (3c)
- anaerobic
2
Q
glycolytic pathway is aka
A
embden-meyerhoff
3
Q
1 molecule of glucose is converted into ____ molecules of pyruvate?
A
2
4
Q
anaerobic glycolysis
A
-conversion of glucose to lactate
5
Q
aerobic means
A
oxygen present
6
Q
once pyruvate is formed, there are several different fates. List them
A
- Anaerobic glycolysis
- Aerobic oxidation
- Anaerobic alcoholic fermentation
7
Q
List the very basic process of glycolysis
A
- glucose (6c) is converted to fructose-1,6-biphosphate (6c)
- fructose-1,6-biphosphate gives rise to 2 molecules of pyruvate (3c)
8
Q
What is the net production of ATP in glycolysis?
A
2
9
Q
Catabolic Pathways
A
breaking bonds
10
Q
Anabolic Pathways
A
make bonds
11
Q
When energy is consumed there is a _____ delta G.
A
Positive
12
Q
Endergonic Rxn
A
energy consumed; +delta G
13
Q
Exergonic Rxn
A
energy released; - delta G
14
Q
Enthalpy
A
heat content of a reacting system
15
Q
Exothermic Rxn
A
releases heat and has a negative delta G
16
Q
Endothermic Rxn
A
Put in or consume heat; positive delta G
17
Q
dG= dH-TdS
A
relationship between G, H, S
18
Q
When are reactions favorable?
A
when they are spontaneous; delta G is negative
19
Q
When delta G is positive a reaction is or is not spontaneous
A
is not
20
Q
If enthalpy is decreasing and entropy is increasing the reaction will be:
A
favorable
21
Q
Condensation Rxn are energetically_______
A
un-favorable
22
Q
Hydrolysis Rxn are energetically ______
A
favorable
23
Q
Overall, you always want delta G to be?
A
negative
24
Q
Energy from ________ reactions is used for _______ reactions
A
catabolic; anabolic
25
Are reactions involving the assembly of polymers usually condensation rxn or hydrolysis rxn?
condensation
26
Enzymes _______ reactions.
Catalyze or accelerate
27
How does enzymes catalyze reactions?
by lowering the activation energy of a reaction. they dont change the overall delta G
28
What needs to be overcome to proceed?
activation energy
29
In catalysis, are both reactions accelerated to the same degree?
Yes.
30
Oxidation is the ______ of electrons. Reduction is the ______ of electrons.
Loss; Gain
31
NAD+/NADHwhich is oxidized?
NAD
32
FAD/FADH2which is reduced?
FADH2
33
What do activated carriers do?
store energy until it is ready to be used
34
What is the most abundant activated carrier?
ATP, because of phophoanhydride bonds
35
Where does glycolsis occur?
Cytosol
36
How many steps is glycolsis?
10 steps catalyzed by 10 different enzymes.
37
Does Glycosis occur under anaerobic (No O2) conditions?
yes.
38
Glycolysis yields:
2 pyruvate per 1 glucose
39
What is the net energy carrier production of glycolysis?
2 ATP & 2 NADH
40
What are the two phases of glycosis?
Preparatory and Pay-off Phase
41
What does the preparatory phase do?
preparing glucose for cleavage
42
In the preparatory phase how many ATP is consumed?
2
43
What reactions are part of the preparatory phase?
Rxn 1-4 (sometimes 5)
44
What is Step 1 of Glycolysis?
Name: Hexokinase (also glucokinase)
- phosphorlyation of glucose, addition of phosphate traps glucose in cell, uses 1 ATP
- gives rise to glucose-6-phopshate
- Rxn is irreversable.
- delta G= is negative (exergonic)
45
What is Step 2 of Glycolysis?
Name: Phosphohexose Isomerase (glucose phosphate isomerase)
- rearrangment of glucose-6-phosphate to fructose-6-phosphate
- Rxn is irreversable.
- delta G= is negative (exergonic)
46
What is Step 3 of Glycolysis?
Name: Phosphofructokinase
- addition of phosphate ensures both molecules are contained in the cell after cleavage of glucose, uses 1 ATP
- gives rise to fructose-1,6-biphosphate
- Rxn is irreversable.
- delta G= is negative
- First step where molecule is commited to going through glycolysis
47
What is Step 4 of Glycolysis?
Name: Aldolase
- fructose-1,6-biphosphate (6C) is cleaved into two 3C molecules
- Rxn is reversible due to cellular conditions
- only glyceraldhyde-3-phosphate can proceed
48
What is Step 5 of Glycolysis?
Name: Triose Phosphate Isomerase
- phosphorlyation of glucose, addition of phosphate traps glucose in cell.
- forms another molecule of glyceraldehyde-3-phosphate from unusable dihydroxyacetone phosphate formed in step 4
- Rxn is reversable.
49
How many irreversible reactions are in glycolysis?
3
50
Glycolsis Payoff phase is steps ___ thru ____?
6-10
51
What happens overall in the payoff phase?
Produces 4 ATP & 2 NADH
52
What is Step 6 of Glycolysis?
Name: Glyceraldehyde 3-phosphate dehydrogenase
- Redox rxn, forms high energy bond in product
- reversible
- Produces: 1,3-Biphospoglycerate
- very important!
53
What is Step 7 of Glycolysis?
Name: Phosphoglycerate kinase
- high energy bond from 1,3-bisphospoglycerate provides energy for formation of ATP.
- reversible under cellular conditions
- first step where we generate ATP from phosphorylation of ADP
54
What is Step 8 of Glycolysis?
Name: Phophoglycerate mutase
- movement of phosphate group (from 3 to 2)
- reversible
55
What is Step 9 of Glycolysis?
Name: Enolase
- removal of water (dehydration reaction) creates high energy enol-phosphate linkage
- Mg2+ is needed as a co-factor
- reversible
56
What is Step 10 of Glycolysis?
Name: Pyruvate Kinase
- synthesis of ATP, pyruvate formation
- irreversible
57
Are Steps 6 & 7 are coupled? If so, how?
Yes. In step 6, we are oxidizing carbon which releases energy. That energy is used to reduce NADH and form a high energy bond.
58
Fermenatations lead to
excretion of lactate excretion of alchohol and CO2
59
Fermenation occurs in what type of conditions?
anerobic
60
In what conditions does the citric acid cycle occur in?
aerobic
61
What do you put into glycolysis?
glucose, 2 ADP, 2Pi, and 2 NAD+
62
What do you get out of glycolysis?
2 Pyruvate, 2 NADH, 2H+, 2 ATP, 2 H2O
63
Citric acid cycle is also called
krebs cycle
64
where does the citric acid cycle occur in eukaryotes?
mitochondria
65
In the citric acid cycle, what must first happen to the pyruvate from glycolysis?
It has to be made into acetyl-CoA
66
Pyruvate Dehydrogenase happens in
mitochondrial nucleus
67
Pyruvate Dehydrogenase Complex
Complex of 3 enzymes that catalyze 5 reactions, located in mitochondrial matrix
68
Complex 1 in Pyruvate Dehydrogenase:
remove one carbon from pyruvate
69
Complex 2 in Pyruvate Dehydrogenase:
transfer of two carbons to CoA
70
Complex 3 in Pyruvate Dehydrogenase:
making sure reaction can continue to occur
71
Overall Energy Carrier Production from 1 acetyl-CoA (x2 for each glucose)
3 NADH, 1 FADH2, 1 GTP
72
Distinguish between the preparatory and payoff phase of glycolysis.
Preparatory phase consumes 2 ATP
| Payoff produces 4 ATP & 2 NADH
73
What are the net products of glycolysis?
2 Pyruvate, 2 ATP, 2 NADH, 2H+, 2 H20
74
Where does glycolysis occur?
Cytosol
75
Which reactions are irreversible in glycolysis?
Three phosphorylation steps catalyzed by kinases.
| Step 1, Step 3, Step 10
76
What is the first committed step?
Step 3
77
How do products from glycolysis enter the citric acid cycle?
Pyruvate must be processed to acetyl-CoA by the pyruvate dehydrogenase complex in the mitochondrial matrix in order for products to enter the citric acid cycle
78
NADH from glycolysis results in a lower/higher ATP yield than other NADH
lower
79
Glycolysis and Cancer
Glycolysis goes faster than normal because there is a limited O2 supplythe cells take up more glucose than normal cells due to more transporterscompounds that inhibit steps of glycolysis are often used in treatment
80
Glycolysis and Type 1 Diabetes
too few beta cells in the pancreas cause low insulin levels, leading to insufficient uptake of glucose by cells. can lead to lowered blood pH due to products of fatty acid oxidation
81
lowered blood pH
Ketoacidosis
82
Glycolysis and Type 2 Diabetes
development of insulin resistance- more insulin is required to achieve the same effects
83
When are ketone bodies produced?
prolonged fast or starvation (glucose is unavailable, glycogen deplettion, and gluconegenesis occurs)
84
Gluconeogenesis
glucose synthesis, uses acetoacetate to try to make glucose.
85
Ketone bodies function as
acids, which makes blood more acidic
86
When we dont have glucose for a long period of time... our bodies try to make
glucose
87
glucose-6-phosphate inhibits what enzyme?
hexokinase
88
glucokinase does what to blood glucose levels
lowers them after eating
89
when glucose levels are low, is hexokinase still active in the tissues?
Yes
90
When hexokinase is bound to substrate, the conformation is...
close together. the two lobes are almost completely surrounded by a protein. consistent with induced fit theory. so cleft closes.
91
In step 2 of glycolysis, glucose phosphate isomerase does what?
C-1 aldehyde group of glucose-6-phosphate is reduced to a hydroxyl group and the C-2 hydroxyl group is oxidized to give a ketone group of fructose-6-phosphate
92
glucose-6-phosphate is in the _____ form whereas fructose-6-phosphate is in the _____ form
aldose; ketose
93
glucose phosphate isomerase
the enzyme that catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate
94
phosphofructokinase
- the key allosteric control enzyme in glycolysis
- catalyzes phosphorylation of fructose-6-phosphate
- tetramer
95
Phosphofructokinase as a tetramer
- two subunits: M & L
| - different combos can give rise to different permutations
96
isoenzymes
multiple forms of an enzyme that catalyze the same overall reaction but have subtle physical and kinetic parameters
97
subunits M & L
-each have different amino acid compositions, so can be separated by electrophoresis
98
M4
- in muscle
| - homogenous
99
L4
- in liver
| - homogenous
100
At high levels of ATP, phosphofructosekinase behaves ______ and plots _______
cooperatively; sigmoidal
101
High levels of _____ inhibits phophofructosekinase and then decreases the enzymes affinity for fructose-6-phosphate
ATP
102
aldolase
in glycolysis, the enzyme that catalyzes the reverse aldol condensation of fructose-1,6-bisphosphate
103
What is the major product from steps 1-5 in glycolysis?
formation of 2 molecules of glyceraldehyde-3-phosphate
104
Describe in detail step 6 of glycolysis?
- addition of phosphate group to glyceraldhyde-3-phosphate
- electron transfer from glyceraldhyde-3-phosphate to NAD+
- ATP is not used
- overall reaction is slightly endergonic
105
glyceraldehyde-3-phosphate dehydrogenase is a __mer
tetramer; consists of four identical subunits
-each subunit binds one molecule of NAD+ and contains cysteine residue (thioester containing this is key intermediate in rxn)
106
phosphoglycerate kinase
the enzyme that catalyzes the transfer of a phosphate group from 1,3-bisphophoglycerate to ADP
107
substrate-level phosphorylation
- a reaction in which the source of phosphorus is inorganic phosphate ion, not ATP
- standard free energy of the hydrolysis reaction must be more negative than that for hydrolysis of new phosphate compound being formed
108
In which step of glycolysis does the net production of ATP equal the net loss of ATP?
step 7-phosphoglycerate kinase
