BIOS 10161 Lecture Notes - Lecture 9: Blood Sugar, Cell Signaling, Volvox

24 views7 pages

amaranthcricket286

12 Sep 2016

School

Department

Biological Sciences

Course

BIOS 10161

Professor

Schulz, Robert

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Some signal transduction pathways include small, non-protein molecules called second messengers that mediate some steps: discovered in research on the liver enzyme glycogen phosphorylase, which is activated by epinephrine. Second messenger 1: these experiments confirmed the existence of a second messenger cyclic. Produced from atp by the enzyme adenylyl cyclase, which is activated via a g protein-linked epinephrine receptor. Second messengers serve to amplify and distribute the signal: binding of one epinephrine molecule = production of many camp, camp molecules activate many enzyme targets, also involved in cross talk. Second messengers 2 and 3: formed when phospholipids in the membrane are hydrolyzed by phospholipases. Ex: hydrolysis of pip2 (phosphatidyl inositol biphosphate: pip2: Hydrophobic portion (diacylgycerol dag) embedded in membrane. Hydrophilic portion (inositol triphosphate ip3) projected into cytoplasm. Hydrolyzed by phospholipase c: ip3 and dag both secondary messengers that activate protein kinase c (pkc) Pkc family of protein kinases that can phosphorylate many proteins causing a variety of cell responses.

Related Questions

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

cerisehedgehog846

1. Hormones are chemical signals that
A.
affect adjacent cells.
B.
work in prokaryotes.
C.
are autocrine signals.
D.
travel through circulatory systems.
E.
are paracrine signals.

Answer choice C

2. A universal feature of receptors is that they
A.
undergo structural (shape) changes when the signal molecule isbound.
B.
are protein kinases.
C.
are present in the plasma membrane.
D.
are ion channel proteins.
E.
do not undergo structural (shape) changes when the signal moleculeis bound.

Answer choice A

3. Which of the following statements about receptors and enzymes istrue?
A.
Most receptors and enzymes are nucleic acids.
B.
Both receptors and enzymes may be integral membrane proteins.
C.
Receptor ligands, like enzyme substrates, are altered during signaltransduction.
D.
Both receptors and enzymes are not specific for the molecules theybind.
E.
Receptors generally have enzymatic activity, whereas enzymes donot.

Answer choice B

4. Chemical signal transduction pathways
A.
use non-specific receptors.
B.
involve binding of the signal molecule to receptors.
C.
use receptors that are located only on the plasma membrane.
D.
use receptors that change the ligands they bind.
E.
all use G proteins.

Answer C

5. Adenylyl cyclase
A.
is located such that cAMP is made outside of cells.
B.
makes cAMP from ATP with the liberation of phosphate (Pi).
C.
is inactivated by activated G proteins.
D.
makes cAMP from ATP with the liberation of pyrophosphate(PPi).
E.
is directly activated by receptors.

Answer choice D

6. Which of the following statements is true?
A.
Glycogen phosphorylase in liver cells is always active.
B.
cAMP is referred to as a âfirst messenger.â
C.
Epinephrine directly activates adenylyl cyclase.
D.
cAMP is referred to as a âsecond messenger.â
E.
Adenylyl cyclase is a protein kinase.

Answer choice C

7. Which step of the signal transduction cascade that results inglucose release during the âfight-or-flightâ response does notdirectly involve a nucleotide?
A.
Phosphorylation of glycogen phosphorylase
B.
Activation of adenylyl cyclase
C.
Epinephrine binding to its receptor
D.
Activation of a G protein
E.
Inactivation of glycogen synthase

Answer choice A

8. The phosphorylation of proteins by ATP
A.
is catalyzed by enzymes known as âprotein kinases.â
B.
always stimulates the activity of an enzyme.
C.
is catalyzed by adenylyl cyclase.
D.
is catalyzed by the epinephrine receptor.
E.
is catalyzed by G proteins.

Answer choice A

9. Suppose the concentration of epinephrine in the blood stream ofan animal drops. The cyclic AMP concentration in liver cells wouldbe expected to _______ because _______ activity would_______.
A.
increase; adenylyl cyclase; increase
B.
decrease; protein kinase; decrease
C.
decrease; phoshodiesterase; decrease
D.
increase; protein kinase; increase
E.
decrease; adenylyl cyclase; decrease

Answer choice B

BIOS 10161 Lecture Notes - Lecture 9: Blood Sugar, Cell Signaling, Volvox

Document Summary

Get access

Related textbook solutions

Molecular Cell Biology

Biology: Science for Life with Physiology

Biology

Concepts of Biology

Essentials of Biology

Related Documents

BI110 Lecture Notes - Lecture 11: Adenylyl Cyclase, Phosphorylase Kinase, Glycogen Phosphorylase

BIOL 1201 Chapter : Learning Objectives Number 4

BSC 300 Lecture Notes - Lecture 13: Gluconeogenesis, Ef Hand, Oligomer

Related Questions