Question

Which steps in glycolysis produce ATP?

Answer 1

Hint: We need to know that glycolysis is the foundation for cellular respiration for both aerobic and anaerobic respiration. In Glycolysis, the conversion of glucose to pyruvate takes place. Glucose is a six membered ring formed as a result of breakdown of carbohydrates into sugars. All the glycolytic enzymes are present in the cytosol.
The overall reaction of glycolysis that occurs in the cytoplasm can be simply given as:
$$C_6{H}_{12}{O}_6+2NA{D}^{+}+2ADP+2P\to 2C{H}_3(C=O)COOH+2ATP+2NADH+2H^{+}$$

Complete answer:
Glycolysis is a 10-step process which leads to the formation of pyruvate molecules by partial oxidation of glucose. The production of ATP occurs in step 7 and 10. The reaction that occur has given as follows:
Step 7: Phosphoglycerate Kinase – PGK is used to transfer phosphate group from 1,3 bisphosphoglycerate to ADP giving the product ATP and 3-phosphoglycerate
Enzyme PGK us used to convert1,3 bisphoglycerate to 3-phosphoglycerate. The phosphate group that is lost is transferred to a molecule of ADP that yields us the ADP molecule. 2 molecules of ATP are produced since 2 molecules of 1,3 bisphoglycerate. With synthesis of 2 molecules of ATP, we have compensated the loss of 2 ATP in the previous steps of Glycolysis, leaving us with 0 molecules of ATP up to this stage of glycolysis.
Magnesium atoms are involved to shield the negative charge on the Phosphate Group of the ATP molecules. The reaction can be given as:
$1,3-bisphoglycerate+ADP\underset{PGK/Mg}{\overset{}{\to }}3-phosphoglycerate+ATP$
Step 10: Pyruvate Kinase – This enzyme is used to transfer P from phosphoenolpyruvate (PEP) to ADP to form pyruvic acid and ATP.
This is the final step in the process of glycolysis that converts Phosphoenolpyruvate (PEP) into pyruvate catalyzed by the enzyme Pyruvate Kinase. As the name suggests, this reaction involves the transfer of the Phosphate group. The phosphate group in PEP is transferred, to yield ATP. Again, since two molecules of PEP are used, 2 molecules of ATP are produced. The number of ATP produced in Glycolysis can be given as:
Step 1 and 3 = -2ATP
Step 7 and 10 = +4ATP
Net ATP produced = 2
Upon finishing the process of glycolysis, the cell immediately continues respiration, aerobic or anaerobic, based upon the conditions of the surroundings. In the presence of oxygen a cell can perform aerobic respiration and will continue on the aerobic citric acid cycle in the mitochondria. In the absence of oxygen, the cell performs anaerobic respiration called homolactic fermentation. Example yeast can only perform anaerobic respiration called alcoholic fermentation.

Note:
Now we can see the 10 steps involved are:
Hexokinase
Phospoglucose Isomerase
Phosphofructokinase
Aldolase
triosephosphate isomerase
Glyceraldehyde-3-phosphate dehydrogenase (GAPDH)
Phosphoglycerate kinase
phosphoglyceromutase
Enolase
Pyruvate Kinase