BIOB11H3 Study Guide - Final Guide: Leucine Zipper, Chemotherapy, Tubulin

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limefly147

5 Dec 2010

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Nucleus = site of storage for genetic material to be replicated/expressed. Often om studded w/ rb and attached to er. Nuclear lamina = dense meshwork (made up of lamins = intermediate filaments), lies on inner surface of nuclear envelope, disintegrates during mitosis and results in phosphorylation j mechanical support for envelopes and site of attachment of chromatin. Nucleus has major control j e. g. hela cells: contain 10,000,000 ribosomes: single nucleus has to import 560,000 proteins and import 14,000 rb subunits every minute. Proteins that enter nucleus have nuclear localization signal j stretches of positively charged aa j function as. Proteins that move out have nuclear export signals. l-gtp release w/ hydrolysis j needs accessory ran-gap1. Only about 5% of human dna encodes functional rnas and proteins chromosomes = made of dna and associated proteins (nucleoprotein) = chromatin. 2 types of proteins in chromatin: 1) histones = most abundant in chromatin, small basic proteins.

Related Questions

2. Before nuclear pore complexes were well understood, it wasunclear whether nuclear proteins diffused passively into thenucleus and accumulated there by binding to residents of thenucleus such as chromosomes, or were actively transported andaccumulated regardless of their affinity for nuclearcomponents.
A classic experiment that addressed this problem used several formsof radioactive nucleoplasmin, which is a large pentameric proteininvolved in chromatin assembly. In this experiment, either theintact protein or the nucleoplasmin heads, tails, or heads with asingle tail were injected into the cytoplasm or into the nucleus offrog oocytes. All forms of nucleoplasmin, except heads, accumulatedin the nucleus when injected in the cytoplasm, and all forms wereretained in the nucleus when injected there.
A. What portion of the nucleoplasmin molecule is responsible forlocalization inthe nucleus?
B. How do these experiments distinguish between active transport,in which a nuclear localization signal triggers transport by thenuclear pore complex, and passive diffusion, in which a bindingsite for a nuclear component allows accumulation in thenucleus?

orangezebra695

1. The histones that form the core of the nucleosome get into the nucleus by which of the following?

a) Passive diffusion through nuclear pores

b) Selective and facilitated active transport through nuclear pores

c) Ribosomes located in the nucleus synthetize histones in the nucleus

d) Histones are made at the ER membrane and then diffuse to the nucleus

2. Membrane proteins that belong to the golgi, lysosome, or plasma membrane first pass through which organelle before reaching their final subcellular destination?

a) The golgi apparatus

b) The smooth ER

c) The nucleus

d) The ER membrane

e) The ER lumen

3. Where in the cell would a ribosomal protein be located if it has had its nuclear export signal inactivated (non-functional or non-existent).

a) The protein would be found in the ER lumen

b) The protein would remain in the nucleus

c) The protein would be secreted

d) The protein would remain in the cytoplasm

e) The protein would be in the ER membrane

4. Where would be the final destination of a protein if it contained a NLS anywhere in the protein sequence (and which is exposed to the cytoplasm after protein folding) but also contained an ER signal sequence at the carboxy terminus?

a) The ER lumen

b) The nucleus

c) The cytoplasm

d) The inner nuclear membrane

e) The ER membrane

5. The sequence K-D-E-L serves as a retention/retrieval signal for ER proteins.

a) True

b) False

6. The following are true for both cell membrane proteins and secretory proteins EXCEPT?

a) Precursors of the mature proteins contain signal sequence.

b) Both types of proteins contain stop-transfer sequences

c) Both types of proteins enter the ER while being synthetized

d) Both types of proteins pas through the golgi apparatus

e) Both are carried by clatherin-coated vesicles

7. If you isolate a regulated secreted protein from a secretory/storage vesicle and inject it into the cytosol, is will?

a) Be secreted through channels in the plasma membrane

b) Be taken up into secretory vesicle and secreted

c) Remain in the cytosol until it is degraded

d) Be taken up into the rough ER and follow the secretory pathway

goldmanatee250

1)A friend works in a biotechnology company and has discovered a drug that blocks the ability of ran the echange GDP for GTP. What is the most likely effect of this drug on nuclear transport?

a)nuclear transport receptors would be unable to bind cargo.

b)nuclear transport receptors would be unable to enter the nucleus

c)nuclear transport receptors would be unable to release their cargo in the nucleus

d)nuclear transport receptors would interact irreversibly with the nuclear pore fibrils

2)After isolating the rough endoplasmic reticulum the the rest of the cytoplasm, you purify the mRNAs attached to it. Which of the following proteins do you expect the mRNA from the rough endoplasmic reticulum to encode?

a) plasma membrane proteins

b)ER membrane proteins

c)Soluble secreted proteins

d)all of the above

3)For both actin and microtubule polymerization, nucleotide hydrolysis is important for?

a)stablilizing the filaments once they are formed

b)increasing the rate at which subunits are added to the filaments

c)promoting nucleation of filaments

d)decreasing the binding strenth between subunits on filaments

indigohare858

BIOB11H3 Study Guide - Final Guide: Leucine Zipper, Chemotherapy, Tubulin

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