Question

1) Which of the following steps cannot contribute to the regulation of gene expression?

Remodelling of the chromatin

Processing the mRNA.

DNA replication

Initiation of RNA transcription.

The stability of the mRNA.

2) Which of the following statements is true about "housekeeping" genes?

The DNA of housekeeping genes has tighter conformation around the histones than that of inducible genes.

Housekeeping genes are often methylated.

The DNA of housekeeping genes has looser conformation around the histones than that of inducible genes.

Housekeeping genes have unexposed transcription factor (TF) binding elements.

Only a few cells have housekeeping genes.

3) Which of the following statements about the Pre Initiation Complex in eukaryotes is not correct?

The Pre Initiation Complex of proteins assembles at the -10 and -35 sequences.

TF IID assembles at ~ -32 to -24 site along with other transcription factors.

TF IID contains TATA-binding proteins and assembles at the TATA box.

The function of the Pre Initiation Complex in eukaryotes is to place and orient RNA polymerase II so that transcription can be initiated.

RNA polymerase II begins to elongate when it dissociates from the PIC.

4) Which of the following statements about the lac operon is correct?

The Lac promoter is strong so it requires a repressor for negative control.

The Lac promoter is strong because its sequence does not deviate greatly from the consensus sequence.

The Lac promoter is weak because it requires cAMP for transcription.

The Lac promoter is weak because its sequence deviates significantly from the consensus sequence.

Answer 1

1) Correct option - DNA replication

Remodeling of chromatin - Here chromatin transforms from condensed state to accessible state by histone acetylation and DNA methylation.

Processing mRNA - In this process, introns are removed and the mRNA strand is converted to a mature mRNA strand, which is ready to get translated into a peptide chain.

DNA replication - It is a process of formation of a copy of the DNA strand. This process does not contribute to gene expression.

Initiation of RNA transcription - It is the first step of transcription. In this step, enhancer, promoter, RNA pol, and other transcription factors are bought together to regulate the gene expression.

mRNA stability - mRNA stability regulates gene expression as it is dependent on mRNA degradation.

2) Correct option - The DNA of housekeeping genes is loosely bound around histone as compared to that of the inducible genes.

The DNA of housekeeping genes is tightly bound around histone as compared to that of the inducible genes. This statement is wrong. This is because housekeeping genes need to keep a watch on cellular activities even in normal conditions. If the DNA for these genes is tightly bound to histone, then it will not get transcripted into the gene easily.

Housekeeping genes are often methylated - This option is wrong. These genes have CpG islands which are not generally methylated.

Housekeeping genes have unexposed TF - This is wrong because these genes have exposed transcription factors.

Houskeeping genes are found in fewer cells - These genes are expressed in all cells. Therefore, this option is incorrect.