Circle the correct answer in brackets and explain your answe

Circle the correct answer in brackets and explain your answer below. If elements A-E provide positive control, then the control elements for both genes are considered [silencer/enhancer/promoter-proximal) elements. b. Assume that element A is a silencer and elements B, C and D are enhancers. Which combination of regulators will cause a high level of expression for the fantasia gene? Select all that apply. a. A, B, C, D b. A and C c. B and D d. A and D e. C and D

Solution

a) Both promoter-proximal elements and enhancers exert the positive control over gene regulation. However, the promoter-proximal elements are located close to the promoter while the enhancers are the regulatory sequences and proteins that are present far from the promoter. In the given image, since the positive control elements are present far from promoter, they are \"enhancers\".
b) Answer: C and E
The promoter-proximal elements and enhancers exert the positive control over gene regulation while silencers are the negative control elements and serve to reduce the gene expression. So, among the given combinations, all that have \"A\" will give lesser gene expression as compared to those having B, C and D.
Therefore, high level of gene expression can be obtained by \"B and D\" and \"C and D\" regulatory elements.