Question

question 3 enzymes can catalyze a reaction only if they encounter a molecule of atp. their active site is sufficiently oxidized. they have both products in their active site at the same time. they encounter a substrate that fits their active site.

Explanation:

Enzymes are biological catalysts. Their function is based on the lock - and - key model or induced - fit model where a specific substrate must bind to the active site of the enzyme for the catalytic reaction to occur. ATP is not a requirement for all enzyme - catalyzed reactions. Oxidation of the active site is not a general prerequisite. Enzymes bind substrates, not products, to start a reaction.

Answer:

they encounter a substrate that fits their active site.