Chapter 16- Glycolysis and Gluconeogenesis

Question 1

What is the main pathway for metabolizing glucose?

Answer 1

Glycolysis

Question 2

Which pathway is the preferred macronutrient fuel for most cells?

Answer 2

Glycolysis

Question 3

How many carbons does glucose have and what is it classifies as?

Answer 3

A 6 Carbon sugar

Question 4

How many carbons does pyruvate have?

Answer 4

3 carbons

Question 5

What are the 3 stages of metabolism?

Answer 5

Stage 1: digestion and absorption
- happens outside of cells
*********

Question 6

What are the 3 stages of glycolysis?

Answer 6

C6 stage: Investment
Another stage: Splitting
C3 stage: Harvesting

Question 7

What does the splitting stage do in glycolysis?

Answer 7

The conversion of 6 carbons to 3 carbons

Question 8

What is the C6 stage also called?

Answer 8

The investment stage

Question 9

What does the C6 stage include in glycolysis?

Answer 9

the hexokinase and the phosphofructokinase-1 (PFK-1) reactions as well as others

Question 10

what does a kinase do?

Answer 10

transfers a phosphate from one organophosphate onto another

Question 11

What do hexokinases do?

Answer 11

They transfer a phosphate onto hexoses.

Question 12

what is the first reaction in glycolysis?

Answer 12

glucose + ATP using a hexokinase to get glucose 6 phosphate and ADP and H+

Question 13

Is the first reaction in glycolysis heavily favored or not favored?

Answer 13

Yes, it is because ATP -> ADP is highly favored because its unstable. And because ATP is a high energy organophosphate

Question 14

What type of organophosphates are sugars?

Answer 14

They are low energy organophosphates

Question 15

What’s the delta G for the hydrolysis of ATP?

Answer 15

7.3 kilocalories/mole

Question 16

Why is the C6 stage called the investment stage?

Answer 16

Because we spend 2 molecule of ATP.*

Question 17

Why is the first investment of ATP worthwhile ?

Answer 17

Because the glute transporter is passive.

Question 18

the glute transporter is an example of

Answer 18

a passive transporter

Question 19

what does the glute transporter do for glycolysis?

Answer 19

The glucose that leaks into the cell can also leak outside of the cell.

Question 20

Hexokinase phosphorylating it does what ?

Answer 20

it traps it into the cell because glucose 6 phosphate cant go through the glute transporter

Question 21

After the 1st investment in glycolysis what is next?

Answer 21

an isomerase reaction

Question 22

what are isomerases?

Answer 22

enzymes that catalyze the making of one isomer to another

Question 23

what is the delta G for an isomerization?

Answer 23

near 0

Question 24

what is the isomerase reaction?

Answer 24

takes glucose 6 phosphate to fructose 6 phosphate using an isomerase

Question 25

what is the committed step in glycolysis?

Answer 25

fructose 6 phosphat spending a ATP using PFK 1 to get fructose 1,6 bisphosphate and ADP and H

Question 26

is the committed step a favorable reaction?

Answer 26

yes, because it goes from high energy ATP to 2 low energy phosphoester bonds

Question 27

is the committed step another investment?

Answer 27

yes you spent the second molecule of ATP

Question 28

why is the second molecule of ATP worthwhile to invest?

Answer 28

because you cut the 6 carbon into quantity 2 3 carbon compounds

Question 29

what is the committed step enzyme of glycolysis?

Answer 29

PFK-1 phosphofructoskinase 1

Question 30

What are the inputs of glycolysis?

Question 31

What are the outputs of glycolysis?

Question 32

How is glycolysis regulated?

Question 33

What are the two parts of the splitting stage of glycolysis?

Answer 33

splitting and interconversion reactions

Question 34

Explain the splitting stage.

Answer 34

take fructose 1,6 bishophaste and split it into quantity 2 3 carbon sugars dihydroxyacetone phosphate (DHAP) and glyceraldehyde 3 phosphate (GAP)

Question 35

how are DHAP and GAP related to each other?

Answer 35

they are isomers of each other.

Question 36

what interconverts DHAP into GAP? and what is the delta g of this reaction?

Answer 36

an isomerase, near zero

Question 37

how many GAP molecules do you get 1 per glucose molecule?

Answer 37

2 GAP molecules

Question 38

The last stage of glycolysis is called the what?

Answer 38

c3 stage or harvesting stage

Question 39

what does the C3 stage include?

Answer 39

the glyceraldehyde 3 phosphate dehydrogenase reaction (GAP DH) producing NADH

Question 40

is NADH energy currency? if so what is NADH?

Answer 40

no thats ATP but it can be converted into ATP it is a high energy electron carrier

Question 41

what is our first yield in glycolysis?

Answer 41

1 NADH in the C3 harvesting stage

Question 42

what are we harvesting in the C3 stage?

Answer 42

NADH 2 molecules of ATP

Question 43

how many ATP to we get at the end of glycolysis?

Answer 43

2 ATP

Question 44

Why is GAPDH so important?

Answer 44

1. because what it does is very unique 2. and its the first of many similar enzymes (that are in the Rossmann fold family of enzymes)

Question 45

what makes someone a Rossmann fold family member?

Answer 45

has the saddle (a alpha helix in the center and two binding sites on the side most often adenosine and niacin)

Question 46

whats the role of NAD? and involved in what kind of reactions?

Answer 46

a high energy electron carrier redox reactions

Question 47

almost all rossmann fold family members are what kind of enzymes?

Answer 47

redox enzymes

Question 48

is redox important in energy metabolism?

Answer 48

yes probably the single most important

Question 49

why is GAP DH called GAP DH?

Answer 49

its substrate is GAP and a dehydrogenase it takes off a hydrogen (not dehydration, not taking off waters)

Question 50

redox takes off?

Answer 50

electrons

Question 51

dehydrogenases are redox _______?

Answer 51

catalysts

Question 52

What Rossman fold family member is NAD dependent?

Answer 52

GAP DH

Question 53

Why is GAP DH different from other Rossman fold family members?

Answer 53

It couples two reactions: phosphorylation and oxidation (1/2 reaction the other 1/2 is a reduction)

Question 54

What does the other 1/2 reaction of the reduction piece do in the NAD DH reaction?

Answer 54

it reduces NAD+ to NADH

Question 55

what is the first harvest in the glycolysis pathway?

Answer 55

NADH (from the reduction step)

Question 56

GAP DH is not just a dehydrogenase but it is also a.....

Answer 56

phosphorylase (because it attaches an inorganic phosphate to an organic molecule)

Question 57

Are thioesters high or low energy?

Answer 57

They are high energy

Question 58

Is GAP DH a member of the Rossmann fold family?

Answer 58

Yes, it is NAD dependent

Question 59

What does the GAP DH step do?

Answer 59

makes bisphosphate dehydrogenase

Question 60

what are the two labels for GAP DH?

Answer 60

dehydrogenase and phosphorylase (because it atatches an inorganic phosphate to an organic molecule

Question 61

How is GAP DH similar and unique to other enzymes?

Answer 61

similar: rossmann fold family member unique: it couples two reactions (phosphorylation and the redox reaction) and forms an acyl phosphate (which has a carboxylic ester bond which makes it high energy)

Question 62

What are the two reactions that GAP DH couple?

Answer 62

phosphorylation of the carboxylic group and a redox reaction which is 1/2 an oxidation and the other 1/2 a reduction from NAD+ to NADH

Question 63

what is our first harvest?

Answer 63

NADH

Question 64

Which step does our first NADH come from?

Answer 64

GAP DH specifically the reduction reaction NAD+ to NADH

Question 65

If the two reactions that are coupled by GAP DH were seperated what would happen?

Answer 65

separated it would not happen spontaneously and the redox reaction is very favorable and the phosphorylation would be unfavorable

Question 66

what is the importance of the coupling of reactions? why does it happen?

Answer 66

so that it is spontaneous and because the phosphorylation is highly favorable.

Question 67

what does the C3 stage produce?

Answer 67

ATP and pyruvate

Question 68

what reaction happens after the GAP DH step? What is the Delta G for the reaction and what does that tell us about the reaction? And what is unique about this reaction?

Answer 68

1,3 bishophoglycerate and ADP gets you 3 phosphoglycerate and ATP delta G is close to 0 (reversible) it is done twice, so we break even and get two ATP out of this reaction per glucose molecule

Question 69

what reaction is after PEP?

Answer 69

PEP and ADP ---> pyruvate and ATP using the 2nd kinase in the C3 stage

Question 70

what are the next two steps after making 3 phosphoglycerate?

Answer 70

3 phosphoglycerate ---> 2 phocphoglycerate 2 phosphoglycerate ---> phosphoenolpyruvate

Question 71

What is unique about PEP?

Answer 71

it has the highest energy of any organophosphate

Question 72

where does the phosphate come from in PEP?

Answer 72

the phosphate comes from the enol bond to take ADP to ATP

Question 73

what do kinases do?

Answer 73

they take a high energy phospho ester and transfer it to a phosphate on ADP to make ATP