Question

It is known that Gene C encodes a protein that binds to the transcription promoter of gene D, and the expression of Gene D leads to wing elongation.Based on the information provided above, propose a possible function of gene C that can explain the difference in body features of original insects and long-wing mutant insects.

Answer 1

Answer:

Normally genes are divided into structural genes and regulatory genes.

Structural genes that carry the information for the synthesis of an enzyme or protein involved in metabolism or anabolism. It is responsible for the expression of the trait.

Control genes regulate the expression of structural genes. The control genes are three types.

(i) Regulatory gene: Code for regulatory protein which can act as an activator or repressor. The activator can enhance the gene expression and the repressor suppress the gene expression.

(ii)Promoter controlling DNA: Promoter of the short nucleotide sequence of DNA that acts as the site that binds to RNA polymerase and initiates transcription. Any alteration in configuration of promoter, prevent binding of RNA pol.

(iii) Operator gene for DNA: is short nucleotide sequence that acts as site for the binding of regulatory protein to operator. The binding of regulatory protein alter configuration of operator DNA. Thereby allowing or preventing the gene expression.

Explanation: C gene is the regulatory gene that encoding for the regulatory protein. This regulatory protein is an activator. This can bind to the promoter region of D gene and enhances the expression of D gene.

Two conditions

(a) Normal or lack of C:   Expression of D gene is normal. So wing length of insect is normal.

(b) presence of C: Expression of D is induced by C. So overexpression leads to long wing mutant insect.