Essential Knowledge 3.D.1

Cell communication processes share common features that reflect a shared evolutionary history.

Communication involves transduction of stimulatory or inhibitory signals from other cells, organisms or the environment.

Correct and appropriate signal transduction processes are generally under strong selective pressure.

In single-celled organisms, signal transduction pathways influence how the cell responds to its environment. Examples include:

• Use of chemical messengers by microbes to communicate with other nearby cells and to regulate specific pathways in response to population density (quorum sensing)
• Use of pheromones to trigger reproduction and developmental pathways
• Response to external signals by bacteria that influences cell movement

In multicellular organisms, signal transduction pathways coordinate the activities within individual cells that support the function of the organism as a whole. Examples include:

• Epinephrine stimulation of glycogen breakdown in mammals
• Temperature determination of sex in some vertebrate organisms
• DNA repair mechanisms

Students should be able to:

LO 3.31 Describe basic chemical processes for cell communication shared across evolutionary lines of descent.

LO 3.32 Generate scientific questions involving cell communication as it relates to the process of evolution.

LO 3.33 Use representation(s) and appropriate models to describe features of a cell signaling pathway.