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TLS Online TPP Program

#Question id: 2897

The transcription of most protein coding genes in mammals (~70 percent) occurs at a lower rate than at TATA box–containing and initiator-containing promoters and begins at any of several alternative start sites within regions of about 100–1000 bp that have an unusually high frequency of CG sequences. Which one of the following best explains it?

#Unit 2. Cellular Organization

  1. CG-rich sequences are bound by histone octamers more tightly than CG-poor sequences because less energy is required to bend around the histone octamer forming a nucleosome.

  2. During housekeeping gene expression, the enzyme methyltransferase is temporarily silenced by miRNA, thus shutting down global methylation.

  3. As soon as the cytosine is methylated in the promoter region, the enzymes of DNA repair pathways remove the methyl group, thereby ensuring gene expression.

  4. A remarkable feature of the CpG islands is that transcription from these elements is initiated in both directions, even though only transcription of the sense strand yields an mRNA.

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TLS Online TPP Program

#Question id: 2447

#Unit 2. Cellular Organization

In the axonemes, the arrangement of nine outer doublet microtubules, as well as the protofilament number of each outer doublet, is specified by
TLS Online TPP Program

#Question id: 2448

#Unit 2. Cellular Organization

Axonemal dynein

a. may contain two or three head domains.

b. attaches to a B tubule through its base domain.

c. consists of heavy, intermediate and light chains.

d. is a (-) end-directed motor.            

e. is an ATPase.
TLS Online TPP Program

#Question id: 2449

#Unit 2. Cellular Organization

What is the correct order of the stages of mitosis?

a. anaphase               

 b. metaphase              

c. telophase    

d. prophase                 

e. prometaphase
TLS Online TPP Program

#Question id: 2450

#Unit 2. Cellular Organization

Which of the following contribute(s) to pole separation during anaphase B?

a. cytosolic dynein     

b. a (-) end-directed kinesin               

c. CENP-E                     

d. microtubule depolymerisation                   

e. microtubule polymerization
TLS Online TPP Program

#Question id: 2451

#Unit 2. Cellular Organization

The average lifetime of microtubules during mitosis is
TLS Online TPP Program

#Question id: 2452

#Unit 2. Cellular Organization

Intermediate filaments

a. are typically 6 nm in diameter.                  

b. are essential for cell motility.

c. may be used to diagnose the tissue of origin for many cancers.

d. are composed of globular subunits.                       

e. are formed from tetrameric subunits.