Question

Molecular and Cell Biology Questions

1- Cell ________________, is a property involving the maintenance of gene expression patterns important for sustained cell identity.

a. proliferation b. memory c. pluripotency d. none of the above

2- Which of the following is not involved in posttranscriptional control?

a. Spliceosome b. Dicer c. Mediator d. RISC

3- The tryptophan operator ___________________________.

a. is an allosteric protein. b. binds to the tryptophan repressor when the repressor is bound to tryptophan. c. is required for the production of the mRNA encoded by the tryptophan operon. d. is important for the production of the tryptophan repressor.

4- The ribosome is composed of two subunits: the __________________ subunit, which catalyzes the formation of the peptide bonds that link the amino acids together into a polypeptide chain, and the __________________ subunit, which matches the tRNAs to the codons of the mRNA.

a. Alpha, Beta b. Large, Small c. Small, Large d. None of the above

The answers are b, c, b and b respectively. But, can you explain why?

Answer 1

1- Cell memory, is a property involving the maintenance of gene expression patterns important for sustained cell identity.

Cell memory os the ability of cells to remember and propagate their gene expression. For e.g. stem cells established at later stages of development can maintain their identity throughout the entire development.

2- c. Mediator

Mediator protein is involved in DNA replication

3.b. binds to the tryptophan repressor when the repressor is bound to tryptophan.

Presence of tryptophan shuts off trp operon because the repressors binds at the operator.

4- c. Small, Large

a smaller subunit binds to the mRNA pattern, and
a larger subunit binds to the tRNA, the amino acids, and the smaller subunit.