The horizontal axis of the cladogram depicted below is a timeline that extends from 100,000 years ago to the present; the vertical axis represents nothing in particular. The labeled branch points on the tree (V-Z) represent various common ancestors. Let's say that only since 50,000 years ago has there been enough variation between the lineages depicted here to separate them into distinct species, and only the tips of the lineages on this tree represent distinct species.

 In Darwin's tree of life, each fork in the tree represents ________.

#Question id: 599

#Unit 1. Molecules and their Interaction Relevant to Biology

In a certain enzyme-catalyzed reaction the following steps occur:

1. A phosphate group on substrate A is transferred to a side chain of an active site residue of the enzyme.

2. The dephosphorylated form of substrate A dissociates from the enzyme.

3. Substrate B enters the active site and is phosphorylated with simultaneous regeneration of the enzyme in its original form.

What kind of kinetic mechanism is described?

#Question id: 600

#Unit 1. Molecules and their Interaction Relevant to Biology

Two substances are used to produce a certain biological product in an enzyme-catalyzed reaction. It is found that both substrates must bind to the enzyme, first one, then the other before the product is produced. This is an example of a/an ________.

#Question id: 601

#Unit 1. Molecules and their Interaction Relevant to Biology

In a ping-pong reaction which does not occur?

#Question id: 602

#Unit 1. Molecules and their Interaction Relevant to Biology

An inhibitor binds to a site other than the active site of the enzyme. Which statement below correlates with this observation?

#Question id: 603

#Unit 1. Molecules and their Interaction Relevant to Biology

Nonclassical competitive inhibition involves ________.

#Question id: 604

#Unit 1. Molecules and their Interaction Relevant to Biology

An enzyme is irreversibly inhibited by diisopropylfluorophosphate (DFP). What does this show?