BIO-2600 Lecture 1: Cell Bio 2

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salmonminnow597

22 Feb 2018

School

App State

Department

Biology

Course

BIO-2600

Professor

Darren Frederick Seals

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Document Summary

All protein sorting processes begin in the cytosol on free floating ribosomes, or on membrane bound ribosomes studding the cytosolic face of the er. The localization of a ribosome depends on the protein it is making. Er bound ribosomes are making proteins that have a hydrophobic signal sequence for import into the er. Free ribosomes are making proteins that lack those signals. Er, the golgi, endosomal compartments, the lysosome, and the plasma membrane. Proteins destined for any part of the endomembrane system, including cathepsin b, are synthesized from. Er bound ribosomes and first get translocated into the er. A unique positive sorting signal promotes the translocation of proteins into the er. Proteins with these unique amino-terminal sorting signals (er signal sequences) are translocated into the er concurrently with their translocation from mrna at ribosome. Er translocation is a 5 component, 5 step process.

Related Questions

6. True or false

a_______ Nuclear pore complexes are specialized so that some mediate import and others mediate export

b_______ Membrane-bound and free ribosomes, which are structurally and functionally identical, differ only in the proteins they happen to be making at a particular time.

c_______ Some proteins can be made as either free or membrane-bound proteins. They have the same mRNA but different splicing and poly-adenylation patterns

d_______ a protein that does not have a sorting signal will be tagged for destruction by ubiquitin

e_______ when the hydrophobic signal peptide emerges from the ribosome, it is bound by SRP, which causes a pause in protein synthesis. Synthesis resumes when the ribosome with a bound SRP then binds to the SRP receptor on the cytosolic surface of the rough ER.

f________ A protein cannot leave the ER unless it is correctly folded

g________ All of the glycoproteins and glycolipids in intracellular membranes have their oligosaccharide chains facing the cytosolic side, and all those in the plasma membrane have their oligosaccharide chains facing the outside of the cell.

29 Most proteins destined to enter the endoplasmic reticulum _________.

(a) are transported across the membrane after their synthesis is complete.

(b) are synthesized on free ribosomes in the cytosol.

(d) are keep binding to Signal recognition particle (SRP) while they are translated.

30 Which of the following choices reflects the appropriate order of locations through which a protein destined for the plasma membrane travels?

(a) lysosome â endosome â plasma membrane

(b) ER â lysosome â plasma membrane

(d) ER â Golgi â plasma membrane

31 Which of the following statements about vesicle budding from the Golgi is false?

(a) COPII can initiate vesicle budding on Golgi membrane.

(b) Some vesicles budded from Golgi membranes move towards ER.

(d) Clathrin molecules act at the cytosolic surface of the Golgi membrane.

32 Which of the following statements is false?

(a) The signal sequences on mitochondrial proteins are first bound to translocator on outer membrane after translation.

(b) Most mitochondrial proteins are not imported from the cytosol but are synthesized inside the mitochondria.

(c) Chaperone proteins in the mitochondria facilitate the movement of proteins across the outer and inner mitochondrial membranes.

(d) Mitochondrial proteins cross the membrane in their unfolded state.

orangeplatypus673

Second messengers play an important role in cellcommunication.

Which of the following best describes their role?

		None
		integrate, amplify and distribute messages throughout thecell
		Release messages to other cells?
		Receive information at the cell surface

What is true of disulfide bonds?

	a.	They often occur in the cytosol
	b.	They are a noncovalent bond
	c.	They are formed enzymatically in the ER
	d.	They act as reducing agents
	e.	they increase protein flexibility

Which of the following is NOT an example of a cell communicationmolecule?

		nucleases
		nitric oxide
		hormones
		kinases

What is true of binding pockets?

	a.	They only occur in the membrane
	b.	They occur in unfolded proteins
	c.	They contain electrostatic interactions
	d.	They contain variable amino acids
	e.

What is true of cell signaling?

	a.	Extracellular signals transduced by rectors always alter cellbehavior very quickly
	b.	Some cells require cell signals just to survive
	c.	Cell signals can be interpreted differently by differentcells
	d.	B and C only
	e.	All of the above (A, B and C)

Histone tails can be modified to change the shape and"tightness" of the nucleosomes. Acetylated histones result in whicheffect?

		Open DNA
		increased transcription
		closed DNA
		decreased transcription
		1+2
		1+4
		3+4
		2+3

Shifting the two bound tRNA from the A and P sites to the E andP sites of the ribosome involves:

	a.	The movement of the small ribosome subunit down the mRNAchain
	b.	The degradation of the A site on ribosome
	c.	The synthesis of the E site on the ribosome
	d.	The movement of the large subunit relative to the smallsubunit
	e.	All of the above

Intracellular signaling pathways are awesome! What is the onething they can NOT do?

	a.	relay the signal, to spread it through the cell
	b.	nothing, they can communicate any cellular need
	c.	distribute the signal to more than one effector protein
	d.	integrate the signal from more than one cellular pathway
	e.	Amplify the signal received, making the signal stronger

Specificity of protein/protein and protein/DNA binding isdetermined by what?

		Non-covalent bonds
		Hydrophobic interactions
		Covalent bonds
		shape of the binding site
		all of the above
		none of the above
		1,2,3
		1,2,4
		1,3,4

The coiling structure of the DNA into chromosomes is achieved bywhat?

		alpha helix
		beta pleated sheets
		chaperone proteins
		DNA/Protein complexing

Which regions (s) of the DNA are found in the final protein?

	a.	poly-A tail
	b.	A and B
	c.	Exons
	d.	UTRs
	e.	Introns

Metabolic processes can be turned "on" and "off" by chemicalmodifcation.

Which chemical modification do we associate with changing theactivity of an enzyme in a transient/non-permanent manner?

		Phosphorylation
		Ubiquitination
		Methylation
		Acetylation

DNA hybridization involves attaching a florescent dye towhat?

	a.	Antibody
	b.	Nuclear stain
	c.	Probe DNA
	d.	tRNA
	e.	rRNA

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BIO-2600 Lecture 1: Cell Bio 2

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