Question

Transposons are movable elements of DNA that insert into new positions within the genome. A transposon may disrupt normal gene function, confer an evolutionary advantage, or have no effect on the organism.
A. Aquisition of a transposon carrying an adhesin gene into the Lactobacillus casei genome.
B. Acquisition of a transposon that disrupts.
C. Insertion of a transposon encoding a heat shock protein into the genome of a plant.
D. Insertion of a transposon into the gene encoding Factor VIII, an essential blood-clotting protein.
E. Undefined.

Answer 1

Answer:

The answer is incomplete because it is imperative to know what is the result of the transposition (i.e., deleterious, beneficial or neutral). For example, A and C options represent study cases where the insertion of Transposable Elements (TEs) may result beneficial for the organism.

Explanation:

Transposable Elements (TE) are mobile genetic elements that have the ability to move within the genome. According to their mechanisms of insertion, TEs are classified into two major classes: Class I (or retrotransposons) and Class II (DNA transposons), which are capable of moving by copy-paste (i.e., by a RNA intermediate) and cut-paste mechanisms, respectively.  

Although originally were considered to be parasitic (deleterious) genetic mobile elements, nowadays it is well known that they may be sometimes beneficial depending on the localization of the TE insertion. For example, TE insertion into a protein-coding region (exon) sequence it is likely to produce protein disruption and thereby it has a deleterious effect. However, the insertion of TEs into upstream and intron non-coding regions may confer gene regulatory activity and be eventually beneficial to the organism.