9.3 Glycolysis Pathway

Question 1

what is the primary pathway for ATP production under anaeroboic conditions and in cells lacking mitochondria?

Answer 1

glycolysis

Question 2

where does glycolysis take place?

Answer 2

in the cytosol

Question 3

what 4 reactants does glycolysis use?

Answer 3

1 glucose, 2 NAD+, 2 ADP, 2 Pi

Question 4

what 5 products does glycolysis generate?

Answer 4

2 pyruvates, 2 NADH, 2 H+, 2 ATP, 2 H20

Question 5

what does the glucose in glycolysis generate?

Answer 5

2 pyuvates

Question 6

what does the NAD+ in glycolysis generate?

Answer 6

2 NAD+ make 2 NADH and 2 H+

Question 7

what do the 2 ADP and 2 Pi of glycolysois generate?

Answer 7

2 ATP

Question 8

give the overall reaction equation of glycolysis

Answer 8

glucose + 2 NAD+ + 2 ADP + 2Pi double arrow (reversibly yield) 2 pyruvate + 2 NADH + 2 H+ + 2 ATP + 2 H2O

Question 9

what is the overall energy of the glycolysis reaction? what does this mean in terms of the steps

Answer 9

overall is -2,850 kj/mol which is hella energy and since cells are not large enough, energy would be wasted if all done at once, so the reaction is broken down into smaller steps for more efficient energy usage

Question 10

what are the 2 stages of glycolysis?

Answer 10

stage 1: 5 steps of investing ATP
stage 2: 5 steps of earning ATP

Question 11

what do kinases do? how are they used in glycolysis?

Answer 11

transfer a phosphate group between ATP and another substrate; used in glycolysis to make or consume ATP

Question 12

what do isomerases do? how are they used in glycolysis?

Answer 12

change the structure of a substrate while the molecular formula remains the same; used in glycolysis to create isomers

Question 13

what dp phosphatases do? how are they used in glycolysis?

Answer 13

remove a phosphate group from a substrate without using ATP; used in glycolysis to release Pi

Question 14

list 6 classes of enzymes involved in glycolysis

Answer 14

1. kinases
2. isomerase
3. phosphatases
4. aldolases
5. mutases
6. enolases

Question 15

what is consumed in stage 1 of glycolysis?

Answer 15

2 ATP

Question 16

what does stage 1 of glycolysis create and produce? (2)

Answer 16

1. negatively charged molecules that can’t diffuse out of the cell
2. produces 2 glyceraldehyde-3-phosphates for stage 2

Question 17

what are the most important steps of stage 1 of glycolysis and why? (be able to list them out here)

Answer 17

steps 1 and 3 because they are irreversible and consume ATP

Question 18

what is reaction 1 of glycolysis?

Answer 18

glucose and ATP are converted to glucose-6 phosphate and ADP by either hexokinase (in body cells) or glucokinase (in pancreas and liver cells)

Question 19

what happens structurally in reaction 1 of glycolysis?

Answer 19

a phosphate group is added to C6 of glucose

Question 20

list 4 key points of reaction 1 of glycolysis

Answer 20

1. it is irreversible because delta G is very negative! (single arrow in rxn)
2. 1 ATP is consumed (out of 2 in this stage)
3. phosphorylation precents glucose from leaving the cell
4. Mg2+ is required for all kinase reactions to shield negative charges

Question 21

how does glucose-6-phosphate inhibit hexokinase? what does this mean?

Answer 21

G6P binds to hexokinase and inhibits ATP binding by allosteric regulation; means that the 1st step of glycolysis can be regulated by product inhibition feedback

Question 22

what is reaction 2 of glycolysis?

Answer 22

glucose-6-phosphate is converted to fructose-6-phosphate by phosphpglucose isomerase

Question 23

what happens structurally during reaction 2 of glycolysis?

Answer 23

the six-membered ring is converted to a 5-membered ring and the carbonyl is moved from C1 to C2

Question 24

what is a key point about the activation energy of reaction 2 of glycolysis?

Answer 24

it occurs near equilibrium (low activation energy) so it is a concentration-driven reaction

Question 25

what happens in reaction 3 of glycolysis?

Answer 25

fructose-6-phosphate and ATP are converted to phosphofructokinase-1 (PFK-1) and ADP by fructose-1,6-bisphosphate

Question 26

what happens structurally in reaction 3 of glycolysis?

Answer 26

the OH is removed from C1 and a phosphate group is added to C1

Question 27

list 4 key points about reaction 3 of glycolysis

Answer 27

1. it is irreversible!! (single arrow!) 2. 1 ATP is consumed 3. allosterically regulated by energy charge 4. rate limiting step for the entire glycolysis pathway!!!

Question 28

list 3 activators of PFK-1 and a commonality among them

Answer 28

1. AMP 2. ADP 3. fructose-2,6-bisphosphate (all signal low energy charge within cell, activate to get glycolysis going to get more energy)

Question 29

list 2 inhibitors of PFK-1

Answer 29

1. phosphoenolpyruvate 2. ATP

Question 30

what happens in reaction 4 of glycolysis?

Answer 30

fructose-1,6-bisphosphate is converted to dihydroxyacetone phosphate and glyceradehyde-3-phosphate by aldolase

Question 31

what happens structurally in reaction 4 of glycolysis?

Answer 31

our 5-membered ring is split open to yield the two products, each with their own phosphate group

Question 32

list 3 key points about reaction 4 of glycolysis

Answer 32

1. low activation energy, occurs near equilibrium, concentration driven 2. reverse aldo condensation 3. cellular metabolist concentrations favor forward reaction

Question 33

what happens in reaction 5 of glycolysis?

Answer 33

dihydroxyacetone phosphate is converted to another glyceraldehyde-3-phosphate by triose phosphate isomerse, with an enediol intermediate

Question 34

list 3 key points about reaction 5 of glycolysis

Answer 34

1. the activation energy is low, equilibrium, concentration driven 2. both products from reaction 4 enter the pathway 3. products of reaction 5 are quickly removed in steps 6 and 7

Question 35

describe stage 2 of glycolysis

Answer 35

1. 2 G3Ps enter 2. 4 ATP produced 3. 2 NADH produced 4. 2 H+ produced 5. reaction 10 is irreversible!!

Question 36

whawhat is the net ATP gain of glycolysis and why?

Answer 36

net gain of 2; although 4 are produced in stage 2, 2 are invested in stage 1

Question 37

what is important to remember about the reactants and products of stage 2 of glycolysis?

Answer 37

everything happens twice! because 2 G3P enter!!

Question 38

what happens in reaction 6 of glycolysis?

Answer 38

2 G3P, 2 NAD+,and 2 Pi are converted to 2 1,3-bisphosphoglycerates, 2 NADH, and 2 H+ by glyceraldehyde-3-phosphate dehydrogenase

Question 39

what happens structurally in reaction 6 of glycolysis

Answer 39

remove an H from G3Ps, use it to reduce NAD+, and add phosphate groups to the G3Ps

Question 40

list 3 key points of reaction 6 of glycolysis

Answer 40

1. 2 NADH produced 2. oxidation of C1 3. product quickly consumed, reaction is coupled with step 7 so concentration favors the forward reaction

Question 41

what happens in reaction 7 of glycolysis?

Answer 41

2 1,3-bisphosphoglycerates and 2 ADPs are converted to 2 3-phosphpglycerates and 2 ATPs byy phosphoglycerate kinase

Question 42

what happens structurally in reaction 7 of glycolysis?

Answer 42

the phosphate groups are removed from the 1,3-bisphosphoglycerates and added to the ADPs to form 2 ATPs

Question 43

list 3 key points about reaction 7 of glycolysis

Answer 43

1. 2 ATP produced 2. reaction is coupled with step 6 3. intermediate is 2,3-bisphosphoglycerate

Question 44

describe the side reaction that occurs in reaction 7 of glycolysis erythrocytes

Answer 44

2 1,3-bisphosphoglycerates are converted to 2 2,3-BPGs!!! by bisphosphoglycerate mutase, which as we know decreases binding of O2 and loows RBCs to deliver their O2!!; then is converted to 3-phosphoglycerate in regular reaction 7

Question 45

what happens in reaction 8 of glycolysis?

Answer 45

2 3-phosphoglycerates are converted to 2 2-phosphoglycerates by phosphoglycerate mutase

Question 46

what happens structurally in reaction 8 of glycolysis

Answer 46

the phosphate group is shifted from C3 to C2

Question 47

what happens in reaction 9 of glycolysis?

Answer 47

2 2-phosphoglycerates aare converted to 2 phsophoenolpyruvates (PEPs) and 2 H2Os by enolase

Question 48

what happens structurally in reaction 9 of glycolysis?

Answer 48

a dehydration reaction occurs to remove 2 H and 1 O for the H2O release

Question 49

what happens in reaction 10 of glycolysis?

Answer 49

2 PEPs and 2 ADPs are converted to 2 pyruvates and 2 ATPs by pyruvate kinase

Question 50

what happen structurally in reaction 10 of glycolysis?

Answer 50

the phosphate groups are removed from PEPs and added to ADPs to form ATPs

Question 51

list 3 key points about reaction 10 of glycolysis

Answer 51

1. irreversible!!! single arrow in rxn!! 2. 2 ATP produced 3. is actually 2 coupled reactions of PEP to enolpyruvate to pyruvate