Sox9 is an autosomal gene involved in several developmental processes, most notably bone formation. In the gonadal rudiments, Sox9 induces testis formation. Expression of the Sox9 gene is specifically upregulated by the combined expression of Sry and Sf1 proteins in Sertoli cell precursors. Thus, Sry may act merely as a “switch” operating during a very short time to activate Sox9, and the Sox9 protein may initiate the conserved evolutionary pathway to testis formation. Following statements are regarding to the functions of Sox9.

A. It appears to be able to activate its own promoter, thereby allowing it to be transcribed for long periods of time.

B. It activates the ability of β-catenin to induce ovary formation, either directly or indirectly.

C. It binds to cis-regulatory regions of numerous genes necessary for testis production.

D. Sox9 binds to the promoter site on the gene for anti-Müllerian hormone, providing a critical link in the pathway toward a male phenotype.

E. Sox9 inhibits the expression of the gene encoding Fgf9, a paracrine factor.

Which of the following statements are correct?

#Question id: 2863

#Unit 2. Cellular Organization

The promoter of the araBAD operon from E. coli is activated in the presence of arabinose and the absence of glucose and directs expression of genes encoding enzymes required for arabinose metabolism. Unlike the cases of lac and gal genes, where a repressor and an activator work together, here two activators work together: AraC and CAP

#Question id: 2864

#Unit 2. Cellular Organization

In E. coli, the five contiguoustrp genes encode enzymes that sythesize the amino acid tryptophan. These genes are expressed efficiently only when tryptophan is limiting. The genes are controlled by a repressor, just as the lac genes are, although in this case, it is the absence of its ligand (tryptophan) that relieves repression, match trp genes to their gene product,

#Question id: 2865

#Unit 2. Cellular Organization

The trp operon is controlled by repression and attenuation, providing a two-stage response to progressively more stringent tryptophan starvation. But attenuation alone can provide robust regulation: other amino acid operons such as leu and his rely entirely on attenuation for their control. Correct number of codons in leader peptide of leu & his operon  in a row;

#Question id: 2867

#Unit 2. Cellular Organization

Deletion in region 3 enhances operon or rate of transcription (in trp operon); Choose an incorrect statement.

#Question id: 2868

#Unit 2. Cellular Organization

Given the following mutants and conditions, predict the expression of the of the lacZ gene (no expression, basal level of expression, or activated level of expression). A mutant of E. coli that has a mutation in the operator of the lac operon that prevents the repressor from binding

#Question id: 2869

#Unit 2. Cellular Organization

Galactose imported into the yeast cell is converted to galactose 6-phosphate by a pathway involving six enzymes, whose genes are scattered over three chromosomes. Transcription of these genes is regulated by the combined actions of the proteins Gal4p, Gal80p, and Gal3p,