Signal Transduction Pathways

Part A

Which of these acts as a second messenger?

	B
	C
	E
	D
	A

Correct

This is a second messenger.

Part B

Which of these is responsible for initiating a signal transduction pathway?

	A
	B
	C
	D
	E

Correct

This is a signal molecule. The attachment of a signal molecule to a plasma membrane receptor initiates a signal transduction pathway.

Part C

What role does a transcription factor play in a signal transduction pathway?

	By binding to a plasma membrane receptor it initiates a cascade.
	It relays a signal from the cytoplasm to the plasma membrane.
	It activates relay proteins.
	By binding to DNA it triggers the transcription of a specific gene.
	It is a plasma membrane protein that binds signal molecules.

Correct

This is the function of a transcription factor.

Part D

In this animation, which of the following, when activated by a signal transduction pathway, moved from the cytoplasm to the nucleus of a cell?

To view the animation, click here. Then click on the image to start the animation.

	relay protein
	DNA
	plasma membrane receptor protein
	signal molecule
	transcription factor

Correct

Activated transcription factors trigger transcription.

Part E

Which of these is a membrane receptor?

	A
	B
	C
	D
	E

Correct

This is a receptor molecule.

Part F

A signal transduction pathway is initiated when a _____ binds to a receptor.

	G protein
	tyrosine kinase
	calmodulin
	signal molecule
	cyclic AMP

Correct

The binding of a signal molecule to a receptor initiates a signal transduction pathway.

Part G

Which of these acts as a second messenger?

	protein kinase
	G protein
	G-protein-linked receptor
	adenylyl kinase
	cyclic AMP

Correct

Cyclic AMP can act as second messengers.

Part H

Calcium ions that act as second messengers are stored in _____.

	mitochondria
	endoplasmic reticula
	peroxisomes
	chloroplasts
	lysosomes

Correct

The ER stores calcium ions.

Part I

_____ catalyzes the production of _____, which then opens an ion channel that releases _____ into the cell's cytoplasm.

	Protein kinase ... PIP2 ... Na+
	Phospholipase C ... IP3 .... Ca2+
	Adenylyl cyclase ... cyclic AMP ... Ca2+
	Phospholipase C ... cyclic AMP ... Ca2+
	Adenylyl cyclase ... IP3 .... Ca2+

Correct

Phospholipase C cleaves IP3 from a membrane protein, and IP3 then binds to a calcium channel on the ER.

Part J

A protein kinase activating many other protein kinases is an example of _____.

	amplification
	a cellular response
	sensitization
	mutualism
	deactivation

Correct

By activating many other molecules the initial signal is amplified.