AP Biology: Chapter eleven: cell communication

Main questions:

1. Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because?

They amplify the original signal manifold.

2. The activation of receptor tyrosine kinases is characterized by?

Dimerization and phosphorylation

3. Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because?

Intracellular receptors are present only in target cells.

Main Facts:

1. In local signaling, animal cells may communicate by direct contact or by secreting local regulators, such as growth factors or neurotransmitters.

2. Intracellular receptors are cytoplasmic or nuclear proteins.

3. At each step in a pathway, the signal is transduced into a different form, commonly a shape change in a protein.

4. Some pathways regulate genes by activating transcription factors, proteins that turn specific genes on or off.

5.Each catalytic protein in a signaling pathway amplifies the signal by activating multiple copies of the next component of the pathway.

Summary:

Key terms:
1. Signal transduction pathway: a signal on a cell’s surface is converted to a specific cellular response is a series of steps.

2. Local regulators: influence cells in the vicinity.

3. Reception: is the target cell’s detection of a signaling molecule coming from outside the cell.

4. Transduction: the binding of the signaling molecule changes the receptor protein in some way, initiating the process of transduction.

5. Response: In the third stage of cell signaling, the transduced signal finally triggers a specific cellular response.

6. Ligand: The term for a molecule that specifically binds to another molecule, of ten a larger one.

7. Ligand-gated ion channel: is a type of membrane receptor containing a region that can act as a “gate” when the receptor changes shape.

8. Protein kinase: the general name for an enzyme that transfers phosphate groups from ATP to a protein is protein kinase.

9. Protein phosphatases: enzymes that can rapidly remove phosphate groups from proteins, a process called dephosphorylation.

10. cAMP: a compound called cyclic adenosine monophosphate, abbreviated cyclic AMP.

AP Biology