Chapter 19.5, Problem 13SAQ

Summary Introduction

To draw:

A pathway of signal transduction including a ligand, receptor and a transcription factor that activates a gene that inhibits the receptor.

Concept Introduction:

Cell signaling involves a ligand, an extracellular molecule that acts as a signal to activate a membrane receptor protein which in turn, inhibits or activates the molecule. Inhibition refers to stop any reaction.

Explanation of Solution

Pictorial representation:

Fig 1: Pathway of signal transduction.

Fig 1: Pathway of signal transduction.

Explanation:

Signal transduction stands for a group of reactions that occur when a molecule such as hormone attaches to the receptor of cells. Signal transduction has three stages:

1. Reception: a protein molecule (ligand) primary messenger will detect chemical signals. Binding of ligand to receptor occur in this step.

2. Transduction: this will occur with the help of secondary messenger which will help in the stimulation of cells or some changes will take place in the cell.

3. Cellular responses: these can either be positive or negative. If the responses are positive then, it will activate some reactions and if they are negative then, they will inhibit the reactions.

Changes in gene expression occur because of the activation or inhibition.

Conclusion

In this cell signaling is done by using ligand. A ligand is an extracellular molecule that acts as a signal to activate a membrane receptor protein which in turn, inhibits or activates the molecules present in the membrane.