Activin Is a Protein That Normally Exists in a Gradient

question 30

Multiple Choice

Activin is a protein that normally exists in a gradient within certain tissues in developing embryos. Certain undifferentiated cells cultured without activin produce epidermal cells. However, activin induces these same cells to adopt other fates (e.g., blood, muscle, heart) , depending on the concentration of activin. Based on these observations, activin acts as a(n) :

• A) transcription factor.
• B) cell-surface receptor.
• C) morphogen.
• D) second messenger.
• E) activator.

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Definitions:

Reaction Sequence

A series of chemical reactions performed in a specific order to transform a starting material into a desired product through intermediate compounds.

Stepwise Mechanism

A reaction mechanism in which a sequence of discrete steps leads to product formation, each step having its own transition state.

Correct Structure

The accurately determined arrangement of atoms within a molecule verified through experimental data.

Organic Product

A compound containing carbon that is typically produced through the chemical reactions of organic compounds.