Cell Signaling and Regulation

Many signal transduction pathways use second messengers to:

• transport a signal through the lipid bilayer portion of the plasma membrane.

• relay a signal from the outside to the inside of the cell.

• relay the message from the inside of the membrane throughout the cytoplasm.

• amplify the message by phosphorylating proteins.

Which of the following can activate a protein by transferring a phosphate group to it?

• cAMP

• G proteins

• phosphodiesterase

• protein kinase

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to

• the active site of an enzyme in the cytoplasm that binds to a specific substrate.

• RNA specifying the amino acids in a polypeptide.

• genes making up a chromosome.

• an enzyme with an optimal pH and temperature for activity.

A signal molecule that binds to a plasma-membrane protein is a

• ligand
• second messenger
• protein kinase
• receptor protein

What is a G protein?

• specific type of membrane-receptor protein
• protein on the cytoplasmic side of a membrane
• membrane-bound enzyme
• relay protein

What determines whether a cell is a target cell for a particular signal molecule?

• phosphorylation cascade
• cAMP
• signal receptors
• phosphatase

The 3 steps of signal transduction in order are

• reception, transduction, response
• response, transduction, reception
• reception, response, transduction
• transduction, reception, response

What is being depicted in the image?

• Amplification of the signal molecule

• Enzymatic proteins inhibiting process of the signal transduction pathway

• Kinase groups adding dimer groups to other enzymes

• Diffusion of molecules within the cell due to the signaling molecule

Which letter represents the cell membrane?

• A

• B

• C

• D

• E

Which letter represents the cell surface receptor protein?

• A

• B

• C

• D

• E