BSC 300 Study Guide - Midterm Guide: Nuclear Pore, Gtpase, Prophase

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plumtermite154

26 Apr 2018

School

University of Alabama

Department

Biological Sciences

Course

BSC 300

Professor

jenny

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Document Summary

Synthesis of secreted proteins, integral plasma-membrane proteins, and proteins destined for the. In cotranslational translocation, the signal recognition particle (srp) first recognizes and binds the. In addition, the channel is gated so that it is open only when a polypeptide is being translocated. In post-translational translocation, a completed secretory protein is targeted to the er membrane by interaction of the signal sequence with the translocon: the polypeptide chain is then pulled into the er by a ratcheting mechanism that requires. Atp hydrolysis by the chaperone bip, which stabilizes the entering polypeptide. In bacteria, the driving force for post-translational translocation comes from seca, a cytosolic atpase that pushes polypeptides through the translocon channel. Single-pass membrane proteins contain one or two topogenic sequences. In multipass membrane proteins, each -helical segment can function as an internal topogenic sequence, depending on its location in the polypeptide chain and the presence of adjacent positively charged residues.

Related Questions

please help me answer theses questions correctly

1/ Which of the following are required for one-pass transmembrane proteins?

I. N-terminal signal sequence

II. Binding of SRP to the SRP receptor

III. Presence of stop-transfer sequence

IV. Presence of start-transfer sequence

a) I and III

b) I, II, and III

c) II, III, and IV

d) I, II, III, and IV

___________________

2/ Which of the following statements about the signal-recognition particle (SRP) is FALSE?

a) The SRP binds to the ER signaling sequence after the entire protein has been translated by the ribosome.

b) The SRP cycles between the ER membrane and the cytosol.

c) The SRP is required for peptides destined for either the ER membrane or ER lumen.

d) The SRP recognizes the signal sequence at the N-terminus of the newly forming polypeptide.

______________________

3) t-SNARES are _____.

a) found on the cytosolic side of the vesicle membrane.

b) necessary for recognition and transport of proteins into the nucleus.

c) usually located on the target membrane.

d) necessary for vesicle formation.

ceruleanchimpanzee878

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.

Select ALL of the true statements about protein targeting.

Nucleotides interact with a nuclear import receptor for transport into the nucleus for the process of DNA replication and transcription.

Signal sequences that direct proteins to the correct compartment are added to proteins through post-translational modification.

The SRP receptor functions to maintain the position of the ribosome on the ER membrane during the process of protein sorting to the ER.

Introduction of non-hydrolyzable GTP into a cell would cause an accumulation of importin receptors inside the nucleus.

all of the above are true

none of the above are true

skymanatee186

BSC 300 Study Guide - Midterm Guide: Nuclear Pore, Gtpase, Prophase

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