Glycolysis

Question 1

Glyclolysis Balance Sheet (Input-Output)

Answer 1

Question 2

lactic acidosis

Answer 2

• circulatory insufficiency
  
  • anemia
• mitochondrial enzyme defects
• poisons
  
  • cyanide
  • CO
• cancer
• ethanol intoxication
• hepatic failure

Question 3

Reactions

Answer 3

Kinase
Mutase
Isomerase (aldoseketose)
Hydratase/Dehydratase
Aldolase
Dehydrogenase

Question 4

Question 5

Answer 5

Mutase

Question 6

Answer 6

Isomerase

Question 7

Answer 7

Dehydratase

Question 8

Aldolase

Question 9

Answer 9

Lactate dehyrdrogenase

Question 10

Glycolysis Step 1

Answer 10

Glucose converted to Glucose 6 Phosphate

Mediated by Hexokinase/Glucokinase

ATP expended

Traps Glucose in cell and can go into several pathways

Question 11

Step 2-5

Answer 11

Question 12

Step 2

Answer 12

Conversion of G6P to Fructose 6 phosphate

Mediated by phosphoglucose isomerase: aldose to ketose

Question 13

Step 3

Answer 13

F6P converted to Fructose 1,6 bisphosphate

Medieated by phosphofructokinase 1: rate limiting step

Requires ATP and is irreversible

Commits to glycolysis

Question 14

Step 4

Answer 14

F 1,6 BP cleaved to form Dihydrooxyactone phosphate and glyceraldehyde 3 Phosphate

Mediated by aldolase

DHAP isomerized to glyceraldehyde 3 P

Question 15

Step 5-7

Answer 15

Question 16

Step 5

Answer 16

Glyceraldehyde 3 P to 1,3 Bisphosphoglycerate

Enzyme: glyceraldehyde 3 phosphate dehydrogenase

Requires Pi and NAD+ to NADH

 oxidizes aldehyde and tranfers electrons to NAD+

 Forms high energy thioester bond w/ enzyme that accepts Pi

Question 17

Step 6

Answer 17

1,3 BPG converted to 3-phosphoglycerate

Mediated by phosphoglycerate kinase

High energy acyl phosphate from last step put on ADP

Forms ATP in substrate level phosphoylation

Question 18

Step 7

Answer 18

3 phosphoglycerate to 2 phosphoglycerate

Enzyme: phosphoglycero-mutase

low energy phosphoester converted to high energy bond in 2 steps

This step moves phosphate to 2nd carbon to form 2PG

Question 19

Step 8

Answer 19

Second step in forming high energy bond:

2 PG converted to phosphoenol pyruvate w/ H2O loss

Enzyme: enolase

enolphosphate bond is high energy and can be used to form another ATP (next step)

Question 20

Step 9

Answer 20

PEP converted to pyruvate by pyruvate kinase

ATP formed by transfer of phosphate to ADP

Question 21

Glycerol-3-phosphate Shuttle

Answer 21

Allows oxidation of NADH back to NAD+

Carries the reducing equivelants across inner mito mem

major shuttle of most tissues

NAD+ regenerated by glycerol 3-P dehydrogenase

 transfers electorns to DHAP to form G3P

G3P enters inner membrane and passes e- to FAD

glycerophosphate dehydrogenase donates e- to CoQ of ETC to form ATP

Question 22

Malate Aspartate Shuttle

Answer 22

NAD+ regenerated by malate dehydrogenase: transfers e- from NADH to oxaloacetate to form malate

malate crosses membrane in exchange for alpha-KG

Malate oxidized to oxaloacetate in matrix by malate DH

NADH formed and donates e- to ETC to form ATP

Oxaloacetate transaminated to form aspartate that exits

aspartate converted back to oxaloacetate in cytosol

Question 23

Anaerobic Glycolysis

Answer 23

Pyyruvate converted to lactate via latate dehydrogenase

Produces less ATP but runs faster using more glucose to compensate–> requires high levels of glycolytic enzymes

Results in acid production, H+: can cause lactic acidosis

RBC, WBC kidney medulla, eye, and skeletal muscle relay on anaerobic glycolysis

Question 24

Fate of Lactate

Answer 24

Taken up by liver, heart and muscle and converted back to pyruvate

Liver synthesizes glucose by gluconeogenesis: Cori Cycle

Other tissues convert lactate to pyruvate and send to TCA cycle

Heart is capable of using lactate as fuel