Multiple choice

Which of the following is the first thing that happens when a signal molecule acts on a target cell?

  1. A transcription factor acts on the DNA

  2. The signal molecule binds to RNA

  3. A new protein is made in the target cell

  4. The signal molecule binds to a receptor.

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The first effect of any signal molecule must involve the binding of the molecule to a receptor.