CHS Bioloigy 2023

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

• ligand
• second messenger
• protein kinase
• receptor protein

Protein kinases activate other relay proteins by adding a(n) ____ to them.

• phosphate
• ATP molecule
• cAMP
• GTP

Which letter represents the cell surface receptor protein?

• A

• B

• C

• D

• E

Which letter represents the ligand?

• A

• B

• C

• D

• E

After a ligand binds, the intracellular domain of a receptor protein changes _____, initiating transduction of the signal.

• color

• size

• shape

Receptors for signal molecules __________.

• all work via protein kinases

• are never found in the nucleus of a cell

• may be found embedded in the plasma membrane, or found within the cytoplasm or nucleus

• all work by opening ion channels

• are only found associated with the plasma membrane

What do secondary messengers, like cAMP, do?

• transport a signal through the lipid bilayer

• relay & amplify a signal from the outside to the inside of the cell

• relay & amplify a message from the inside of the membrane throughout the cytoplasm

• dampen the message

Why do hormones not affect every cell in the body when they are released?

• All cells are affected by a hormone when it is released

• A cell needs a specific receptor for the hormone to be affected

• A cell must have the proper ATP levels to activate a cellular response

• Cells need compatible DNA for the hormone to activate transcription of a gene

If a medicine works by blocking a secondary messenger, what effect would it have on that cell signaling pathway?

• It would increase the response if the pathway

• It would trigger the release of more ligands

• It would activate the transcription of a desired gene

• It would inhibit transduction, thus deactivating the response

The source of phosphate for a phosphorylation cascade is __________.

• cAMP

• protein kinase

• GTP

• ATP

• protein phosphatase