Which statements are correct about lac operator;

I. The site bound by the Lac repressor.

II. The lac operator overlaps the promoter, and so the repressor bound to the operator physically prevents RNA polymerase from binding to the promoter and thus inhibit the RNA synthesis.

III. Have 21-bp sequence with twofold symmetric and is recognized by four subunits of Lac repressor, two binding to each half-site.

IV. CAP binds as a dimer to a site similar in length to that of the lac operator, but different in sequence. This site is located some 60 bp upstream of the start site of transcription.

#Question id: 4081

#Unit 3. Fundamental Processes

Which of the following regulatory scenarios of cell-type-specific expression of fibronectin isoforms in humans is (are) consistent with information on known splicing factors?

a. A Tra-like splicing factor expressed in fibroblasts is required for inclusion of EIIIA and EIIIB exons.

b. An Sxl-like splicing factor is required in hepatocytes for exclusion of EIIIA and EIIIB exons.

c. A Tra-2-like factor enhances binding of the cleavage/polyadenylation complex in fibroblasts.

d. A Dsx-like protein is required to inhibit transcription of the fibronectin gene.

#Question id: 4082

#Unit 3. Fundamental Processes

Which of the following is (are) not involved in alternative splicing in eukaryotes?

#Question id: 4083

#Unit 3. Fundamental Processes

Differential splicing of the Ca2+-activated K+ channel gene in ciliated neurons results in

a. hair cells with different response frequencies.

b. different channel isoforms.

c. channels that open at different calcium concentrations.

d. different channel mRNAs expressed in different cells.

#Question id: 4084

#Unit 3. Fundamental Processes

The nuclear pore complex

a. is a large complex made of many different proteins.

b. is an octagonal, membrane-embedded structure with long filaments.

c. is required for transport of all molecules in or out of the nucleus.

d. binds to importin via FG-repeats.

e. hydrolyzes bound GTP to GDP

#Question id: 4085

#Unit 3. Fundamental Processes

When TAT protein fails to bind to the TAR region of the HIV transcript, which of the following statements is (are) true?

#Question id: 4086

#Unit 3. Fundamental Processes

RNA interference

a. utilizes antisense RNA.  

b. utilizes double-stranded RNA.

c. is used to silence expression of genes. 

d. utilizes short interfering RNAs.