1. Steroid hormone receptors are examples of activators that bind to which regul

Question

1. Steroid hormone receptors are examples of activators that bind to which regulatory response element:

a. protein binding domain

b. enhancers

2. DNA sites bound by regulatory transcription factors are:

a. promoters

c. poly-A tails

3. The stability of mRNA can be enhanced by:

a. a short poly-A tail

b.presence of short bits of complementary RNAs (miRNA)

c.addition of acetyl groups

d. all of the above

e. none of the above

4. One mechanism by which regulatory transcription factors called repressors are thought to act is by:

a. by binding to specific activators and preventing their binding to DNA

b. by binding to DNA regulatory sequences in competition with activators

Explanation / Answer

1. (b). enhancers : because enhancers acts as transcriptional factors that directly bind to response elements of genes and activates their transcription.

2 (a) promoters : because during transcription initiation various transcription factors bind to promoter region and regulates transcription.

3 (a) a short poly A tail. as it slows down the degradation of mRNA in cytoplasm thus confers more stability.

4 (b) : by binding to DNA regulatory sequences in competition with activators. eg; as in lac operon .the repressor directly binds to the operator region of the gene and inhibits binding of RNA polymerase.

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