Name: ________________________________________  
           
           
       

Cell Signaling

Part 1: Concept Mapping

There are four signal receptors described in your textbook and
discussed in class. Three of them: G protein-linked receptors,
Protein (tyrosine)-kinase receptors and ion-channel receptors–are
plasma transmembrane membrane receptors. Protein receptors in the
cytoplasm and nucleus are the fourth type. Some signals interact
with plasma membrane receptors (protein receptors for example) to
begin the process of signal transduction. Many signal
transduction

pathways involve a series of changes in different relay
molecules in the pathway, ultimately causing an intracellular
response to the signal molecule. Other types of signals (steroid
hormones for instance) can diffuse through the cell membrane and
interact with intracellular receptors. This is how a molecule like
testosterone can cause transcription of specific genes.

A) To better understand the process of signal transduction,
develop a concept map or flow chart of both the G-protein receptor
system and the tyrosine kinase receptor system. Make sure to
include all of the components and molecules listed for each system.
Feel free to draw diagrams if it helps.

G-Protein receptor system:

signal protein

G-Protein-Linked receptor

plasma membrane

inactive and active G protein

GTP and GDP

inactive and active enzyme

signal transduction pathway

Protein-kinase receptor system

signal protein

tyrosine-kinase receptor

plasma membrane

inactive and active relay proteins

ATP and ADP

signal-transduction pathway

B) Write an explanation of how signal reception by each of the
systems can lead to an intracellular response (the release of Ca+
ions from the cytoplasm for example).

C) Both of these systems can generate elaborate multi-step
signal transduction pathways. These pathways can greatly amplify
the cell’s response to a signal; the more steps in the pathway, the
greater the amplification of the signal. Explain how and why
amplification occurs.