Question

Barbara McClintock discovered mobile elements in corn by analyzing the genetic behavior of two elements, Ds and Ac. The interplay between these two elements has become one of the most interesting stories of discovery in the field of genetics. How do Ds and Ac interact?

A) Ds causes a deletion next to the insertion site of Ac.
B) Ac causes a deletion next to the insertion site of Ds.
C) While Ds moves only if Ac is present in the genome, Ac is capable of autonomous movement.
D) The movement of Ac is dependent on two forms of Ds.
E) Both elements can move only within chromosome 9.

Answer 1

Barbara McClintock discovered that in corn genetics, the Ds element moves only in the presence of the Ac element, which can move on its own. This interaction contributes to gene regulation, with the answer to the student's question being option C.

Step-by-step explanation:

The discovery of mobile elements in corn by Barbara McClintock, specifically her analysis of the genetic behavior of two elements, Ds (dissociation) and Ac (activator), is a milestone in genetics. Ds and Ac interact in a way that Ds moves only if Ac is present in the genome, while Ac can move autonomously.

The Ds element is a transposon that lacks the gene for the transposase enzyme necessary for transposition, while Ac has this gene and facilitates its own movement as well as that of Ds. This essential interaction between the two elements contributes to the regulation of gene expression and can impact phenotypic characteristics such as kernel color in corn plants.

The correct answer to this student's question is: C) While Ds moves only if Ac is present in the genome, Ac is capable of autonomous movement.