AAMC FL Practice Exam

What characterizes a transposon?

1. A non-coding DNA sequence

2. A DNA element that moves within a genome

3. A type of viral genome

4. A stable genetic mutation

The correct answer is: A DNA element that moves within a genome

A transposon is characterized as a DNA element that has the ability to move within a genome. This movement can occur through a process known as "transposition," where the transposon can insert itself into different locations within the DNA of the same organism. Transposons are often referred to as "jumping genes" due to their capability to change positions and this feature plays a significant role in genetic diversity, evolution, and the development of diseases. Transposons can be classified into two main types: DNA transposons, which move by a "cut-and-paste" mechanism, and retrotransposons, which move by an " RNA intermediate." Both types facilitate genetic rearrangements that can lead to variations in gene expression and chromosome structure. This ability to move can affect gene function and contribute to genomic instability, which can have implications in processes such as cancer development and antibiotic resistance. In contrast, other options are not accurate representations of what transposons are. Non-coding DNA sequences can exist without the capability of movement, viral genomes do not define transposons, and while transposons can contribute to mutations, they are not characterized as stable genetic mutations since their position in the genome can change over time.