Steps of Glycolysis

Question 1

Describe step 1 of glycolysis.

Answer 1

Glucose is combined with ATP. A phosphate group is removed from the ATP and added on to the glucose molecule. This is mediated by the enzyme hexose kinase, creating the molecule of glucose 6-phosphate. This is the activation step.

Question 2

Describe step 2 of glycolysis.

Answer 2

The enzyme phosphoglucose isomerase converts glucose 6-phosphate into fructose 6-phosphate. The structure of the molecule is “juggled.” No energy is consumed at this step.

Question 3

Describe step 3 of glycolysis.

Answer 3

The enzyme phosphofructokinase converts fructose 6-phosphate into fructose 1,6-bisphosphate. This step requires the use of one ATP.

Question 4

Describe step 4 of glycolysis.

Answer 4

Glucose 1,6-bisphosphate is split with the aid of the enzyme aldolase to form dihydroxyacetone phosphate and glyceraldehyde 3-phosphate.

Question 5

Describe step 5 of glycolysis.

Answer 5

The enzyme triose phosphate isomerase takes the dihydroxyacetone phosphate and glyceraldehyde 3-phosphate from the previous step and converts them into two molecules of glyceraldehyde 3-phosphate.

Question 6

Describe step 6 of glycolysis.

Answer 6

Catalyzed by glyceraldehyde 3-P dehydrogenase, glyceraldehyde 3-phosphate reacts with inorganic phosphate present in the solution as well as the high energy electron carrier NAD+ in a redox reaction. The aldehyde is oxidized into a carboxylic acid. This allows electrons to be transferred onto NADH. NAD+ is reduced to NADH. Overall, what is created is 1,3-bisphosphoclycerate.

Question 7

Describe step 7 of glycolysis.

Answer 7

The 1,3-bisphosphoclycerate from the previous step is acted upon by phosphoglycerate kinase and undergoes substrate-level phosphorylation. This means one of the phosphate groups from the previous molecule is cleaved off to create ATP. Overall, this creates 3-phosphoglycerate.

Question 8

Describe step 8 of glycolysis.

Answer 8

An enzyme called phosphoglycerate mutase “juggles” the 3-phosphoglycerate from the previous step into 2-phosphoglycerate. No energy input is required.

Question 9

Describe step 9 of glycolysis.

Answer 9

The 2-phosphoglycerate from the previous step is acted on by enolase to generate phosphoenolpyruvate. No energy input is required.

Question 10

Describe step 10 of glycolysis.

Answer 10

Here, another substrate-level phosphorylation occurs. ATP is produced and pyruvate is generated.