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#Question id: 2441


Which of the following statement(s) is (are) true of microtubule assembly?

a. GDP-tubulin normally assembles into microtubules.

b. Microtubule (-) ends grow faster than microtubule (+) ends.

c. Tubulin subunits assemble to form a protofilament.

d. Microtubules consist of multiple protofilaments.

e. Microtubules with a GTP cap will shorten.

#Unit 2. Cellular Organization
  1. c and d 

  2.  a and c  

  3.  b and e   

  4. d and e 

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#Question id: 28776

#Unit 2. Cellular Organization

Which of the following statements is incorrect about actin molecules?

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#Question id: 31295

#Unit 5. Developmental Biology

Which of the following cells become Nieuwkoop center?

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#Question id: 3970

#Unit 3. Fundamental Processes

In bacteria, an operon:

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#Question id: 16127

#Unit 13. Methods in Biology

You are studying regulation of the yeast enzyme glutamine synthetase (GS), which is encoded by the GLN1 gene. You have isolated two mutants, designated  gln2– and gln3–, that give decreased GS activity. Mating of either gln2– or gln3– haploids to wild type produces heterozygous diploids that show normal amounts of GS expression. When you cross either a gln2– or gln3– haploid to a gln1– strain the resulting diploids show normal expression of GS.
The GLN1 gene shows a rather complex regulation in response to different amino acids. When either glutamate (glu) or glutamine (gln) is added to the medium, the amount of GS expression diminished and when both glutamate and glutamine are added to the medium GS expression is shut off completely. The effects of different mutants on the response to glu and gln are shown below.
Which of the models from best fits these experimental results? Complete the model for the regulation of GLN1 that includes the effects of glu and gln.      

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#Question id: 1518

#Unit 4. Cell Communication and Cell Signaling

Following statements are regarding to the some cancers harbor characteristic chromosome alterations. Chronic myelogenous leukemia (CML), a common leukemia in humans, was found to be associated with the Philadelphia chromosome.

A. Philadelphia chromosome is generated by a translocation between chromosomes 22 and 9. The two chromosomes exchange their terminal regions, which leads to a characteristic alteration in the size of chromosome 9.

B. At the breakpoint of this translocation, a new fusion protein, the BCR-ABL fusion, is generated.

C. The BCR-ABL fusion protein is a constitutively active kinase that phosphorylates multiple signal-transducing proteins.

D. If this translocation occurs in a hematopoietic cell in the bone marrow, the activity of the chimeric BCR-ABL oncogene dephosphorylate proteins thereby activating many intracellular signal-transducing proteins.

Which of the following statements are incorrect?