9.2 glycolysis

Question 1

what happens

Answer 1

glucose of 6 carbons is broke down into
2 sugars of 3 carbons
–these sugars are oxidized
–the remaining atoms rearrange to form 2 molecules of pyruvate

Question 2

net products

Answer 2

2 ATP
2 NADH
2 pyruvate
2 H2O

Question 3

step 1: hexokinase

Answer 3

(glucose)
–hexokinase phosphorylates glucose by transferring a phosphate group to it
-traps sugars in because of the charge on the phosphate group makes it a large ion that can’t pass through the plasma membrane easy
–phosphorlyation makes glucose more chemically reactive
(glucose-6-phospate)

Question 4

step 2: phosphoglucoisomerase

Answer 4

(glucose-6-phospate) is converted it its isomer, fructose-6-phosphate
(fructose-6-phosphate)

Question 5

step 3: phosphofructokinase

Answer 5

(fructose-6-phosphate)
-transfers a phosphate group to fructose
-so that the phosphate groups are on opposite sides of the molecule 
--the sugar is ready to split in half 
(Fructose-1, 6-biphosphate)

Question 6

step 4: aldodase

Answer 6

(Fructose-1, 6-biphosphate)
–aldodase splits ^ into 2, 3 carbon sugar isomers:
dihydroxyacetone phosphate and glyceraldehyde 3-phosphate

Question 7

step 5: isomerase

Answer 7

isomerase catalyzes the reversible conversion between the 2, 3carbon sugars

• it never reaches equilibrium since next enzyme only uses glyceraldehyde 3-phosphate
• -so it ends up with 2 molecules of glyceraldehyde 3-phosphate

Question 8

step 6: triose phosphate dehydrogenase (energy payoff phase–everything is done twice because of the 2 isomers)

Answer 8

the enzyme holds glyceraldehyde 3-phosphate in its active site
-the sugar is oxidized by transfer of H+ to NADH
-energy released used to attach a phosphate group to the oxidized sugar (making it have high PE)
–the phosphates come from the pool of phosphate ions that are always in the cytosol
(1, 3-biphosphoglycerate)

Question 9

step 7: phosphoglycerokinase

Answer 9

–substrate level phosphorylation produces 1 ATP per sugar (net of 2 ATP)
–added phosphate group is transferred to ADP
-carbonyl group is oxidized into a carboxyl group –making it an organic acid
(2 molecules of phosphoglycerate=not a sugar)

Question 10

step 8: phosphoglyceromutase

Answer 10

this enzyme relocates remaining phosphate group

preparing the substrate for the next reaction

Question 11

step 9: enolase

Answer 11

the enzyme makes a double bond form by extracting an H2O

• -this makes Phosphoenolpyruvate (PEP)
• -where the electrons are arranged in such a way that the resulting phosphorylated compound has a very high PE that allows step 10 to happen

Question 12

step 10: pyruvate kinase

Answer 12

• -substrate level phosphorylation produces ATP by transferring phosphate group from PEP to ADP
• -leaving pyruvate

Question 13

products

Answer 13

NADH- used in oxidative phosphorylation
ATP
(next step is fermentation or citric acid cycle)