Question

Steps 6 and 7 of glycolysis are catalyzed by the enzymes glyceraldehyde 3-phosphate dehydrogenase and phosphoglycerate kinase, respectively. Together, they ...

1) result in the oxidation of an aldehyde to a carboxylic acid.
2) produce both ATP and NADH.
3) couple the oxidation of a C-H bond to the activation of carrier molecules.
4) catalyze the only glycolytic reactions that create a high-energy phosphate linkage directly from inorganic phosphate.
5) All of the above.

Answer 1

Steps 6 and 7 of glycolysis produce ATP and NADH and involve the oxidation of glyceraldehyde-3-phosphate coupled with the activation of the electron carrier molecule NAD+.

Step-by-step explanation:

Steps 6 and 7 of glycolysis involve crucial enzymes that are responsible for the energy-releasing phase of the pathway. In step 6, the enzyme glyceraldehyde 3-phosphate dehydrogenase catalyzes the oxidation of glyceraldehyde-3-phosphate to 1,3-bisphosphoglycerate, producing NADH in the process. This steps does not require additional ATP but generates a high-energy electron carrier molecule. In step 7, phosphoglycerate kinase converts 1,3-bisphosphoglycerate to 3-phosphoglycerate, which leads to the production of ATP by substrate-level phosphorylation from ADP.

Together, these steps produce both ATP and NADH (option 2). They do not result in the oxidation of an aldehyde to a carboxylic acid (option 1) nor directly create a high-energy phosphate linkage from inorganic phosphate (option 4). The oxidation is coupled to the activation of the carrier molecule NAD+ (option 3). Therefore, the correct response is that steps 6 and 7 of glycolysis produce both ATP and NADH, and couple the oxidation of a C-H bond to the activation of carrier molecules.