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Biochemistry > Chapter 17-Glycolysis > Flashcards

Chapter 17-Glycolysis Flashcards

1
Q

glycolysis

A
  • breakdown of glucose (6c) to pyruvate (3c)

- anaerobic

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2
Q

glycolytic pathway is aka

A

embden-meyerhoff

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3
Q

1 molecule of glucose is converted into ____ molecules of pyruvate?

A

2

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4
Q

anaerobic glycolysis

A

-conversion of glucose to lactate

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5
Q

aerobic means

A

oxygen present

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6
Q

once pyruvate is formed, there are several different fates. List them

A
  • Anaerobic glycolysis
  • Aerobic oxidation
  • Anaerobic alcoholic fermentation
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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)

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8
Q

What is the net production of ATP in glycolysis?

A

2

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9
Q

Catabolic Pathways

A

breaking bonds

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10
Q

Anabolic Pathways

A

make bonds

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11
Q

When energy is consumed there is a _____ delta G.

A

Positive

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12
Q

Endergonic Rxn

A

energy consumed; +delta G

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13
Q

Exergonic Rxn

A

energy released; - delta G

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14
Q

Enthalpy

A

heat content of a reacting system

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15
Q

Exothermic Rxn

A

releases heat and has a negative delta G

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16
Q

Endothermic Rxn

A

Put in or consume heat; positive delta G

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17
Q

dG= dH-TdS

A

relationship between G, H, S

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18
Q

When are reactions favorable?

A

when they are spontaneous; delta G is negative

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19
Q

When delta G is positive a reaction is or is not spontaneous

A

is not

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20
Q

If enthalpy is decreasing and entropy is increasing the reaction will be:

A

favorable

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21
Q

Condensation Rxn are energetically_______

A

un-favorable

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22
Q

Hydrolysis Rxn are energetically ______

A

favorable

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23
Q

Overall, you always want delta G to be?

A

negative

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24
Q

Energy from ________ reactions is used for _______ reactions

A

catabolic; anabolic

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25
Q

Are reactions involving the assembly of polymers usually condensation rxn or hydrolysis rxn?

A

condensation

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26
Q

Enzymes _______ reactions.

A

Catalyze or accelerate

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27
Q

How does enzymes catalyze reactions?

A

by lowering the activation energy of a reaction. they dont change the overall delta G

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28
Q

What needs to be overcome to proceed?

A

activation energy

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29
Q

In catalysis, are both reactions accelerated to the same degree?

A

Yes.

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30
Q

Oxidation is the ______ of electrons. Reduction is the ______ of electrons.

A

Loss; Gain

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31
Q

NAD+/NADHwhich is oxidized?

A

NAD

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32
Q

FAD/FADH2which is reduced?

A

FADH2

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33
Q

What do activated carriers do?

A

store energy until it is ready to be used

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34
Q

What is the most abundant activated carrier?

A

ATP, because of phophoanhydride bonds

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35
Q

Where does glycolsis occur?

A

Cytosol

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36
Q

How many steps is glycolsis?

A

10 steps catalyzed by 10 different enzymes.

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37
Q

Does Glycosis occur under anaerobic (No O2) conditions?

A

yes.

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38
Q

Glycolysis yields:

A

2 pyruvate per 1 glucose

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39
Q

What is the net energy carrier production of glycolysis?

A

2 ATP & 2 NADH

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40
Q

What are the two phases of glycosis?

A

Preparatory and Pay-off Phase

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41
Q

What does the preparatory phase do?

A

preparing glucose for cleavage

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42
Q

In the preparatory phase how many ATP is consumed?

A

2

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43
Q

What reactions are part of the preparatory phase?

A

Rxn 1-4 (sometimes 5)

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44
Q

What is Step 1 of Glycolysis?

A

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
Q

What is Step 2 of Glycolysis?

A

Name: Phosphohexose Isomerase (glucose phosphate isomerase)

  • rearrangment of glucose-6-phosphate to fructose-6-phosphate
  • Rxn is irreversable.
  • delta G= is negative (exergonic)
46
Q

What is Step 3 of Glycolysis?

A

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
Q

What is Step 4 of Glycolysis?

A

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
Q

What is Step 5 of Glycolysis?

A

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
Q

How many irreversible reactions are in glycolysis?

A

3

50
Q

Glycolsis Payoff phase is steps ___ thru ____?

A

6-10

51
Q

What happens overall in the payoff phase?

A

Produces 4 ATP & 2 NADH

52
Q

What is Step 6 of Glycolysis?

A

Name: Glyceraldehyde 3-phosphate dehydrogenase

  • Redox rxn, forms high energy bond in product
  • reversible
  • Produces: 1,3-Biphospoglycerate
  • very important!
53
Q

What is Step 7 of Glycolysis?

A

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
Q

What is Step 8 of Glycolysis?

A

Name: Phophoglycerate mutase

  • movement of phosphate group (from 3 to 2)
  • reversible
55
Q

What is Step 9 of Glycolysis?

A

Name: Enolase

  • removal of water (dehydration reaction) creates high energy enol-phosphate linkage
  • Mg2+ is needed as a co-factor
  • reversible
56
Q

What is Step 10 of Glycolysis?

A

Name: Pyruvate Kinase

  • synthesis of ATP, pyruvate formation
  • irreversible
57
Q

Are Steps 6 & 7 are coupled? If so, how?

A

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
Q

Fermenatations lead to

A

excretion of lactate excretion of alchohol and CO2

59
Q

Fermenation occurs in what type of conditions?

A

anerobic

60
Q

In what conditions does the citric acid cycle occur in?

A

aerobic

61
Q

What do you put into glycolysis?

A

glucose, 2 ADP, 2Pi, and 2 NAD+

62
Q

What do you get out of glycolysis?

A

2 Pyruvate, 2 NADH, 2H+, 2 ATP, 2 H2O

63
Q

Citric acid cycle is also called

A

krebs cycle

64
Q

where does the citric acid cycle occur in eukaryotes?

A

mitochondria

65
Q

In the citric acid cycle, what must first happen to the pyruvate from glycolysis?

A

It has to be made into acetyl-CoA

66
Q

Pyruvate Dehydrogenase happens in

A

mitochondrial nucleus

67
Q

Pyruvate Dehydrogenase Complex

A

Complex of 3 enzymes that catalyze 5 reactions, located in mitochondrial matrix

68
Q

Complex 1 in Pyruvate Dehydrogenase:

A

remove one carbon from pyruvate

69
Q

Complex 2 in Pyruvate Dehydrogenase:

A

transfer of two carbons to CoA

70
Q

Complex 3 in Pyruvate Dehydrogenase:

A

making sure reaction can continue to occur

71
Q

Overall Energy Carrier Production from 1 acetyl-CoA (x2 for each glucose)

A

3 NADH, 1 FADH2, 1 GTP

72
Q

Distinguish between the preparatory and payoff phase of glycolysis.

A

Preparatory phase consumes 2 ATP

Payoff produces 4 ATP & 2 NADH

73
Q

What are the net products of glycolysis?

A

2 Pyruvate, 2 ATP, 2 NADH, 2H+, 2 H20

74
Q

Where does glycolysis occur?

A

Cytosol

75
Q

Which reactions are irreversible in glycolysis?

A

Three phosphorylation steps catalyzed by kinases.

Step 1, Step 3, Step 10

76
Q

What is the first committed step?

A

Step 3

77
Q

How do products from glycolysis enter the citric acid cycle?

A

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
Q

NADH from glycolysis results in a lower/higher ATP yield than other NADH

A

lower

79
Q

Glycolysis and Cancer

A

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
Q

Glycolysis and Type 1 Diabetes

A

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
Q

lowered blood pH

A

Ketoacidosis

82
Q

Glycolysis and Type 2 Diabetes

A

development of insulin resistance- more insulin is required to achieve the same effects

83
Q

When are ketone bodies produced?

A

prolonged fast or starvation (glucose is unavailable, glycogen deplettion, and gluconegenesis occurs)

84
Q

Gluconeogenesis

A

glucose synthesis, uses acetoacetate to try to make glucose.

85
Q

Ketone bodies function as

A

acids, which makes blood more acidic

86
Q

When we dont have glucose for a long period of time… our bodies try to make

A

glucose

87
Q

glucose-6-phosphate inhibits what enzyme?

A

hexokinase

88
Q

glucokinase does what to blood glucose levels

A

lowers them after eating

89
Q

when glucose levels are low, is hexokinase still active in the tissues?

A

Yes

90
Q

When hexokinase is bound to substrate, the conformation is…

A

close together. the two lobes are almost completely surrounded by a protein. consistent with induced fit theory. so cleft closes.

91
Q

In step 2 of glycolysis, glucose phosphate isomerase does what?

A

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
Q

glucose-6-phosphate is in the _____ form whereas fructose-6-phosphate is in the _____ form

A

aldose; ketose

93
Q

glucose phosphate isomerase

A

the enzyme that catalyzes the conversion of glucose-6-phosphate to fructose-6-phosphate

94
Q

phosphofructokinase

A
  • the key allosteric control enzyme in glycolysis
  • catalyzes phosphorylation of fructose-6-phosphate
  • tetramer
95
Q

Phosphofructokinase as a tetramer

A
  • two subunits: M & L

- different combos can give rise to different permutations

96
Q

isoenzymes

A

multiple forms of an enzyme that catalyze the same overall reaction but have subtle physical and kinetic parameters

97
Q

subunits M & L

A

-each have different amino acid compositions, so can be separated by electrophoresis

98
Q

M4

A
  • in muscle

- homogenous

99
Q

L4

A
  • in liver

- homogenous

100
Q

At high levels of ATP, phosphofructosekinase behaves ______ and plots _______

A

cooperatively; sigmoidal

101
Q

High levels of _____ inhibits phophofructosekinase and then decreases the enzymes affinity for fructose-6-phosphate

A

ATP

102
Q

aldolase

A

in glycolysis, the enzyme that catalyzes the reverse aldol condensation of fructose-1,6-bisphosphate

103
Q

What is the major product from steps 1-5 in glycolysis?

A

formation of 2 molecules of glyceraldehyde-3-phosphate

104
Q

Describe in detail step 6 of glycolysis?

A
  • 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
Q

glyceraldehyde-3-phosphate dehydrogenase is a __mer

A

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
Q

phosphoglycerate kinase

A

the enzyme that catalyzes the transfer of a phosphate group from 1,3-bisphophoglycerate to ADP

107
Q

substrate-level phosphorylation

A
  • 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
Q

In which step of glycolysis does the net production of ATP equal the net loss of ATP?

A

step 7-phosphoglycerate kinase

Biochemistry (7 decks)

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