Glyolysis

Question 1

Step 1

Answer 1

Glucose receives a phosphate from ATP, becoming glucose-6-phosphate
Enzyme: hexokinase
Reaction: phosphorylation
Substrate: glucose
Product: glucose-6-phosphate (1 ATP used here)

Question 2

Step 2

Answer 2

Glucose-6-phosphate rearranged into fructose-6-phosphate
Enzyme: phospho-gluco-isomerase
Reaction: isomerization reaction
Substrate: glucose-6-phosphate
Product: fructose-6-phosphate

Question 3

Step 3

Answer 3

Another phosphate group from ATP is attached to fructose-6-phosphate, producing fructose-1,6,bisphosphate
Enzyme: Phosphofructokinase
Reaction: Phosphorylation reaction
Substrate: Fructose-6-phosphate
Product: Fructose 1,6 bisphosphate

Question 4

Step 4

Answer 4

Fructose 1,6 bisphosphate is split into g3p and dap
Enzyme: aldolase
Reaction: hydrolysis or cleavage
Substrate: Fructose 1,6 bisphosphate
Products: DAP and g3p

Question 5

Step 5

Answer 5

DAP produced in reaction 4 is converted into G3P, producing a total of 2 G3P per molecule of glucose
Enzyme: Triose phosphate isomerase
Reaction: isomerization
End of energy-absorbing reactions

Question 6

Step 6

Answer 6

One NADH per g3p or two per glucose molecule is synthesized here

Beginning of energy-releasing reactions
Two electrons and two protons are removed from g3p, some of the energy released in this reaction is trapped by the addition of an additional inorganic phosphate group in the cytosol. Electrons are accepted by Nad+ along with one of the protons, and the other one is lost to the cytosol
Enzyme: glyceraldehyde-3-phosphate dehydrogenase or triose phosphate dehydrogenase
Reaction: dehydrogenation or redox reaction
Substrate: G3P
Products: 1,3-bisphosphoglycerate

Question 7

Step 7

Answer 7

One of the two phosphate groups of 1,3 bisphosphoglycerate is transferred to ADP to produce ATP (one for each molecule of bisphosphoglycerate so 2 per molecule of glucose)
Enzyme: phosphoglycerate kinase
Reaction: substrate-level phosphorylation reaction
Substrate: 1,3,bisphosphoglycerate
Product: 3-phosphoglycerate

Question 8

Step 8:

Answer 8

3-Phosphoglycerate is rearranged, shifting phosphate group from 3rd to second carbon to produce 2-phosphoglycerate
Enzyme: phospho-glyceromutase
Reaction: mutase reaction- shifting of a chemical group to another within same molecule
Substrate: 3-phospho-glycerate
Product: 2-phosphoglycerate

Question 9

Step 9:

Answer 9

Water is lost here (one per molecule so 2 per glucose)
Electrons are removed from one part of 2-phosphoglycerate and delivered to another part of the molecule. Most of the energy lost by the electrons is retained in the product, phosphoenolpyruvate
Enzyme: enolase
Reaction: dehydration
Substrate: 2-phospho-glycerate
Product: phosphoenol-pyruvate

Question 10

Step 10

Answer 10

Another ATP produced here (2 per molecule of glucose)
Remaining phosphate group is removed from phosphoenolpyruvate and transferred to ADP. The reaction forms ATP and the final product of glycolysis, which is pyruvate
Enzyme: pyruvate kinase
Reaction: substrate-level phosphorylation

Question 11

When does the biggest drop in free energy occur

Answer 11

After step 5, when 2 NADH are lost (energy release used to synthesize NADH, resulting in loss of energy)

Question 12

What are the final products of glycolyisis

Answer 12

1. 2 Pyruvates, catalyzed by pyruvate kinase which removes a phosphate from phosphoenol pyruvate and phosphorylates ATP
2. 2 molecules of ATP (net) and 4 ATP total (step 7 and 10, phosphoglycerate kinase and pyruvate kinase)
3. 2 NADH, produced in step 6 and catalyzed by triosephosphate dehydrogenase
4. 2H+, step 6, triose phosphate dehydrogenase, lost to cytosol
   5, 2 H2O, catalyzed by enolase in step 9