cellular control cgp

Question 1

explain how lactase is produced in the cells of the small intestine in humans but not other body cells

Answer 1

The transcription factor that is needed to switch on the lactase gene is expressed in the cells of the small intestine but not other body cells

Question 2

a mutation leads to more transcription factors being attracted to the lactase gene, explain how this could lead to continues high levels of lactase production.

Answer 2

-it could increase the rate of reaction at which the gene is transcribed
-this would mean that more lactase mRNA would be produced, so more lactase will be made

Question 3

give two reasons why a substitution mutation that occurs in a gene may have no effect on protein function

Answer 3

-the triplet will code for the sane amino acid as code is degenerate
-the mutation could produce a protein that codes for a chemically similar amino acid, which functions like the original

Question 4

explain how hox genes affect the development of body plans

Answer 4

-the homeobox sequence of hox genes code for a part of hox proteins called the homeodomain.
-the homeodomain binds to a specific site near the start of its target developmental gene, and acts as a transcription factor
-the homeodomain activates or represses the transcription of the developmental gene and so alters the production of a protein involved in the development of body plan.

Question 5

what triggers apoptosis

Answer 5

apoptosis is triggered by internal/ external stimulus