You Are Studying the Effect of a Secreted Signal Molecule

question 53

Multiple Choice

You are studying the effect of a secreted signal molecule on the activity of a cytoplasmic enzyme.Prior studies have shown the signal molecule is required for enzyme activity.You add the signal molecule to a test tube solution containing both the enzyme and its substrate.After incubating the solution,you assay for the reaction product as a measure of enzyme activity,however,no product was detected.By comparison,when you add the signal molecule to a vial containing intact cells,you are able to detect the reaction product.Which of the following statements is inconsistent with these experimental results?

• A)The cells express a receptor for the signal molecule.
• B)There is no direct interaction between the signal molecule and enzyme.
• C)The cells facilitate a direct protein-protein interaction between the signal molecule and enzyme.
• D)Binding of the signal molecule to its receptor initiates a signal transduction pathway leading to enzymatic activity.

---

Definitions:

Antipoverty Programs

Government or organizational initiatives designed to reduce or eliminate poverty by providing assistance to the needy through services or financial aid.

Public Good

A good or service provided at no cost to every person in a society, delivered by either state institutions or a nonprofit private individual or organization.

Government Intervention

Actions taken by a government to affect the economy, which can include regulations, subsidies, tariffs, and taxes.

Excludable

A characteristic of a good whereby it is possible to prevent people from enjoying the good unless they have paid for it.