BIOL 2021 Lecture : Ch. 15 - Cell Communication - Part 1 A summary of the chapter and lecture notes on cell communication. Includes illustrations and graphics from the textbook.

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greyeel576

16 Oct 2011

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Communication between cells is mediated mainly by extracellular signal molecules. Figure 15-1: a simple intracellular signalling pathway activated by an extracellular signal molecule. The signal molecule usually binds to a receptor protein that is embedded in the plasma membrane of the target cell and activates one or more intracellular signalling pathways mediated by a series of signalling proteins. Finally, one or more of the intracellular signalling proteins alters the activity of effector proteins and thereby the behaviour of the cell. Can include proteins, small peptides, amino acids, nucleotides, steroids, etc. Binds the signal molecule and then initiates a response in the target cell. Usually transmembrane proteins on the target cell surface but can also be inside the cell where signal molecule must enter the cell and bind to them. Figure 15-3a: the binding of extracellular signal molecules to either the cell-surface or intracellular receptors.

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

33 Different glycoproteins can have a diverse array of oligosaccharides. Which of the statements below for making glycoproteins on plasma membrane is true?

(a) Extensive modification of oligosaccharides occurs in the extracellular space.

(b) Initial oligosaccharide chains are made by addition of one sugar at a time onto the protein in the ER lumen.

(c) Each layer of Golgi membrane structures contains identical modification enzymes for modifying sugar chain on proteins.

(d) ER lipids can be modified by sugar chain, which can be used for sugar chain modification of the proteins.

34 In a multicellular organism, when a signal needs to be sent to most cells the signal most suited for this is a ___________.

(a) neurotransmitter.

(b) hormone.

(d) plasma membrane anchored ligands.

35 Typically, members of the steroid hormone receptor family __________________.

(a) are cell-surface receptors.

(b) do not undergo conformational changes by binding to their ligands.

(d) interact with signal molecules that diffuse through the plasma membrane

36 Which of the following statements about what happens when a G-protein-coupled receptor activates a hetero trimeric G protein is true?

(a) The Î² subunit exchanges its bound GDP for GTP.

(b) The GDP bound to the Î± subunit is phosphorylated to form bound GTP.

(d) It activates the Î± subunit and inactivates the Î²Î³ complex

37 Which of the following statements about signal transduction is false

(a) Ca2+ concentration in cytosol will increase when PLC (Phospholipase C) is activated by signal.

(b) Cyclic GMP is made in smooth muscle cells when they received NO signal.

(d) Ligand binding to RTK activates its enzyme activity then the activated RTK phosphorylates tyrosine residues on itself.

greywoodchuck816

Living systems can be studied by way of the scientific method which involves which of the following?

Using only deductive reasoning and not inductive reasoning

Using few subjects, but repeating the experiments and using controls

Using few subjects, but repeating the experiments

Using many subjects, but doing no statistical analysis

Using many subjects but having no controls

Which of the following molecules has the least amount of energy that you can use for intense physical exercise?

A chemically specifically designed to signal uncontrolled cell growth

Water since it promotes all chemical reactions

Lipids

Carbohydrates

Protein

Nicotine produced in plants can be lethal to insects in that it causes a paralysis. Where does nicotine have its effect?

Nicotine receptors located in the nucleus of the cell

Nicotine receptors on the plasma membrane of brain cells

Nicotine receptors in the golgi bodies of neurons

Nicotine receptors on the mitochondria of brain cells

The aqueous (water) space between cells is which of the following?

Blood

Interstitial

Extracellular

Intracellular

All of these answers are correct

A hypo-osmotic solution can be defined as which of the following?

A solution separated from another by way of semipermeable membrane in which the hyposmotic solution has less electrolyes and more water than the other solution

A solution separated from another by way of semipermeable membrane in which the hyperosmotic solution has less electrolyes and more water than the other solution

A solution that is equal in concentration compared to another

A solution that is less concentrated relative to another

A solution that is more concentrated relative to another

Lactic acid in your muscles is the byproduct of which metabolic pathway?

Glycolysis

Electron Transport System

Krebs cycle

Glycolysis and oxygen

Which of the following best describes the process of glycolysis?

A series of chemical reactions in the mitochondria that breakdown or catabolize glucose to produce ATP without oxygen

A series of chemical reactions that breakdown or catabolize protein to produce lactic acid in the presence of oxygen

A series of chemical reactions in the muscle cytoplasm that breaksdown or catabolize glucose to produce ATP without oxygen

A series of chemical reactions that produce enzymes

During oxidative phosphorylation, which of the following is phosphorylated with the assistance of ATP synthase?

Cytochromes

ADP

ATP

NADH

Hydrogen ions

In all animals who use oxidative phorphorylation to generate ATP, the ultimate electron acceptor is directly transported to all cells by way of which of the following?

Hemoglobin

Red blood cells

Water (H2O)

Lungs

After NADH is reduced at the Electron Transport system, the hydrogen ion subsequently does which of the following?

Activates ATPsynthase

Activates Krebs cycle

Activates chemiosmosis

Oxidizes ATP

Reduces ATP

Which of the following has to exist for ATP synthase to be activated to directly produce ATP?

An oxygen gradient

A neutron gradient

An electron gradient

A proton gradient

All of these answers are correct

Which of the following occurs when oxyhemoglobin reaches the capillaries of heart muscle?

Releases oxygen which leaves the capillary and diffuses into the cell

Absorbs oxygen from the mitochondria

Releases its oxygen which diffuses from the mitochondria to the capillary

Releases its oxygen which diffuses from the capillary to the nucleus

BIOL 2021 Lecture : Ch. 15 - Cell Communication - Part 1 A summary of the chapter and lecture notes on cell communication. Includes illustrations and graphics from the textbook.

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