Biology 3597A/B Lecture Notes - Lecture 3: Histidine Kinase, Necrosis, Mycoplasma

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25 Jan 2020

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Lecture #4:Transcription in Bacteria It

Two Component Regulatory Systems in Bacteria

1) Histidine kinase sensor

- often in the cell membrane

- detects environmental signal and auto phosphorylates

histidine kinase phosphorylates itself in response to

receiving a signal , then transfer that phosphate to

the second component Cresponse regulator )

21 Response Regulator

cytoplasmic protein that is phosphorylated by and activated

by ahistidine kinase sensor

- usually a DNA binding transcription factor that activates a

transcriptional network Cmany genes -often called a regular)

transcription factors recruit RNA polymerase to promoters that aren't strong enough on their own

regular : a group of genes that is activated Ctranscribed )by one thing Ctranscription factor )

TCS Example

an example of a two component system is the Pho Pl Ph OR TCS that responds

to low phosphate levels

- this is a two component system from E. coli

-Ph op gets phosphorylated , activates transcription , which activates many genes

in a transcriptional network

this helps phosphate get into the cell ,

even

in alow phosphate environment

- there are about

50 two component

eSg@•

The regular :systems in E. coli

i. e. a high affinity /

Activation of genes and they have

phosphate transport

system that aid in uptake the potential for

of phosphate cross talk

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Document Summary

Histidine kinase sensor often in the cell membrane detects environmental signal and auto phosphorylates histidine kinase phosphorylates itself in response to receiving a signal , then transfer that phosphate to the second component c response regulator ) 21 response regulator cytoplasmic protein that is phosphorylated by and activated by a histidine kinase sensor usually a dna binding transcription factor that activates a transcriptional network. C many genes - often called a regular ) transcription factors recruit. Rna polymerase to promoters that aren"t strong enough on their own regular : a group of genes that is activated. Tcs example an example of a two component system is the pho pl ph or tcs that responds to low phosphate levels this is a two component system from e . coli. Ph op gets phosphorylated , activates transcription , which activates many genes in a transcriptional network this helps phosphate get into the cell even in a low phosphate environment there are about.

Related Questions

Question 3 (5 points)

Match the terms to the definitions provided.

Question 3 options:

	telophase II
	meiosis II
	telophase I
	anaphase I
	anaphase II

1.	Division, beginning without DNA replication, that resembles and produces four haploid cell.s
2.	Phase of meiosis when chiasmata are broken as spindle fibers shorten and homologous pairs are pulled apart.
3.	Phase of meiosis when sister chromatids are pulled to opposite poles of the cells.
4.	Phase of meiosis in which homologues cluster at the poles of the cells and the nuclear envelope reforms.
5.	Phase of meiosis in which four different haploid cells are present.

Question 4 (7 points)

Match the terms to the definitions provided.

Question 4 options:

	G0
	telophase
	G2
	mitosis
	cytokinesis
	cell cycle
	S

1.	The phase in which the cell synthesizes a replica of its genome
2.	The overall process of genome duplication
3.	The phase in the cell cycle during which mitochondria and other organelles replicate.
4.	The phase in mitosis when chromosomes are clustered at opposite poles and the spindle apparatus disappears
5.	A resting state that cells often enter before resuming cell division.
6.	The phase in the cell cycle when the cytoplasm divides creating two daughter cells.
7.	The phase in the cell cycle in which the spindle apparatus assembles and sister chromatids move apart.

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Question 5 (6 points)

Put the events of a MAP kinase cascade in the correct order.

Question 5 options:

	MAPKKK phosphorylates and activates another kinase
	MAPKK phosphorylates and activates MAPK
	Binding of MAPKKK to Ras
	External signal binds to membrane receptor and activates receptor kinase.
	MAPK phosphorylates an inactive response protein and activates it.
	Phosphorylation of receptor kinase and interaction with RAS

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

Some cells in plant and animals are specialized for the production and release of a particular chemical, often a protein or some other regulatory molecule. These cells generally produce and release their product only when the proper signal is present. Describe the series of events in this cell that would lead from the perception of this signal to the release of the desired product. Begin by providing specific information on: 1) the transduction of the signal across the membrane by the G protein system with subsequent release of the appropriate second messenger(s); 2) the process by which the signal is amplified by the MAP kinase pathway; 3) how the product(s) produced by the MAP kinase cascade reach the nucleus to initiate the transcription of the relevant gene(s).

Assume now that transcription has already occurred, that a mature mRNA has been produced in the nucleus and has migrated to the cytosol, and that this mRNA has been recruited by a ribosome to initiate translation. Since the protein product is secretory, synthesis of the protein will be associated with the rough endoplasmic reticulum. Continue by providing information on 4) how the free ribosome becomes associated with the endoplasmic reticulum to allow for the release of the synthesized protein into the rough ER; 5) the modification or processing of the protein that occurs in the endoplasmic reticulum; 6) the packaging and/or modification of the protein for transport from the ER to the Golgi apparatus; 7) the modification, processing, and packaging of the protein in the Golgi apparatus; and 8) the steps leading to the eventual release of the target protein from the cell via exocytosis.

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Biology 3597A/B Lecture Notes - Lecture 3: Histidine Kinase, Necrosis, Mycoplasma

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