BI110 Lecture Notes - Lecture 20: Lipid Bilayer, Cardiac Muscle, Signal Transduction

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ceruleanlion382

29 Apr 2016

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Molecular signals received by cells that have receptors tuned to specific signals(in order for a cell to respond to something, it has to have a receptor that allows it to sense the signal. Different types of cells respond to different types of signals because they have different types of receptors) When signal(whatever the signal is) molecule binds receptor cellular response: In response to a particular signal, a channel can be opened or closed to allow or prevent transport of a molecule across a membrane. Can be regulated in response to particular signals. (metabolic pathways can be turned on/off or increased/decreased) Can be stimulated by presence of particular signal. The need to produce or secrete more can be caused by a signal. (e. g. light as a signal, in response to too much or too little, the cell can move to or from the light) Cells will divide when conditions are optimal.

Related Questions

Which of the following statements is a result of signal amplification?

Multiple Choice

A.) Different types of cells will have differing reactions to a particular signal molecule.

B.) Small concentrations of extracellular signaling molecules can affect a rapid response from a cell.

C.) Endocrine signaling is made possible by signal amplification.

D.) Only high concentrations of extracellular signaling molecules can affect a rapid response from a cell.

E.) All cell types will react similarly to a particular signal molecule.

HUMAN GROWTH HORMONE

1. Describe the ligand and any external receptors that bind to the ligand. If signaling can occur without an external ligand, explain how this can occur.

2. Describe how the signal is translocated from the exterior of the cell to the interior of the cell. Be sure to describe the specific activity of the receptor in initiating the intracellular signal.

3. Describe the propagation of the signal within the cell from the membrane receptor to the point of cellular response. Provide the details for at least one specific protein interaction that either results in the activation or inactivation of a subsequent protein or signaling molecule to propagate the signal.

4. What is a specific cellular response to the signal. Something will change- what is it?

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QUESTION 1

Which of the following is an example of an extracellular signal molecule?

	a.	IP₃
	b.	cAMP
	c.	Insulin
	d.	Diacylglycerol

2 points

QUESTION 2

Nuclear hormone receptors _____

	a.	Bind to water soluble ligands
	b.	Activate second messengers
	c.	Regulate transcription in response to ligand binding
	d.	Are normally located on the plasma membrane

2 points

QUESTION 3

Which of the following does not occur when a receptor tyrosine kinase is bound by ligand?

	a.	Phosphorylation of the RTK
	b.	Cytoplasmic proteins bind the phosphorylated RTK
	c.	Dimerization of the RTK
	d.	The RTK binds to DNA to regulate transcription

2 points

QUESTION 4

Which of these is a logical signal-transduction pathway?

	a.	An intracellular receptor activates phospholipase C, which cleaves a membrane protein to form IP₃, which then activates the opening of an ER channel protein, which releases cyclic AMP into the cytoplasm, where it binds to an intracellular enzyme that carries out a response.
	b.	A G-protein-linked receptor activates G protein, which activates phospholipase C, which cleaves a membrane lipid to form IP₃, which binds to a calcium channel on the ER, which opens to release calcium ions into the cytoplasm, which bind to an intracellular enzyme that carries out a response.
	c.	An ion-channel receptor opens, allowing a steroid hormone to enter the cell; the steroid hormone then activates protein kinases that convert GTP to GDP, which binds to an intracellular enzyme that carries out a response.
	d.	A tyrosine-kinase receptor activates adenylyl cyclase, which activates phospholipase C, which converts ATP into cyclic AMP, which binds to an intracellular enzyme that carries out a response.

2 points

QUESTION 5

Which of the following is an example of signal amplification?

	a.	activation of an enzyme molecule
	b.	activation of a specific gene by a growth factor
	c.	Breakdown of many cAMP molecules
	d.	activation of 100 molecules by a single signal binding event

2 points

QUESTION 6

Consider a signal transduction pathway that utilizes cAMP as a second messenger to activate PKA (Protein Kinase A). Which of the following situations will result in the cellular response?

		The G protein releases GDP and binds to GTP
		The target protein (adenylyl cyclase) is inactive
		The regulatory subunits of PKA (Protein Kinase A) are bound to the catalytic subunits
		The appropriate G protein is bound to GDP

2 points

QUESTION 7

Which of the following is found in only some signal transduction pathways? [In other words, which is not found in all signal transduction pathways?]

		Receptor protein
		Extracellular signal molecule
		Intracellular signaling molecule
		Cellular response
		Effector protein

2 points

QUESTION 8

The enzyme that specifically catalyzes the conversion of ATP to cAMP is:

		Adenylyl phosphatase
		Adenylyl kinase
		Adenylyl dehydrogenase
		Adenylyl cyclase

2 points

QUESTION 9

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

		It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
		It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
		It would employ a transduction pathway directly from an external messenger.
		It would be able to carry out reception and transduction but would not be able to respond to a signal.

2 points

QUESTION 10

A hormone signal is sent from the brain to other parts of the body via the bloodstream. Why do only certain cells respond to this signal?

		Hormones do not last long enough in the bloodstream to stimulate a cellular response
		Only cells that have a specific transcription factor gene will be able to respond to the signal
		Only cells in the immediate vicinity of the cell sending the signal will respond
		Only cells that have a receptor for the specific signal will be able to respond to it

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BI110 Lecture Notes - Lecture 20: Lipid Bilayer, Cardiac Muscle, Signal Transduction

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