Question 1: What would be the effect on tryptophan production of mutations in region 1
of the leader of the trp operon that changed the Trp codons to stop codons? Explain your
reasoning.
The Trp codons, which are DNA sequences that encode tryptophan, are found in region
one of the trp operon. Numerous effects would result from mutations in region 1 of the trp
operon that alter Trp codons to stop codons. Essentially, translation would stop earlier than it
should at those sites, since the ribosome employed for translation would stop prematurely. This
causes the attenuator sequence to be reached before the ribosome can finish translating, which
prevents the attenuation signals from being recognized. It would create the terminator structure
of the attenuator and not produce the anti-terminator structure.
Question 2: Mutations in genes encoding chromatin-remodeling complexes have been
identified in high frequencies in some human cancers. For example, mutations in
components of the human SWI–SNF remodeling complex were found in 19% of tumors in
a group of cancers. How might a mutation in a chromatin-remodeling complex contribute
to cancer?
A chromatin-remodeling complex mutation might contribute to cancer by dysregulating
gene expression, which may have an effect on DNA repair and the regulation of the cell cycle,
such as hindering cell differentiation. As a result, there would be a high frequency of cancer cell
spread in the human body due to lack of tumour suppression, uncontrolled cell proliferation, and
genetic instability.