What is commonly referred to as "jumping genes"?

Transposons, often referred to as "jumping genes," are sequences of DNA that can change their position within the genome. This ability to move from one location to another can lead to mutations and changes in the cell's genetic makeup, which is why they are called "jumping genes." Transposons can be categorized into two main types: Class I, which replicates and inserts copies of itself into new locations (also known as retrotransposons), and Class II, which excises itself from one location and integrates into another.

Their mobility is significant in genetics because transposons can contribute to genetic diversity and evolution. They can also play a role in various biological processes such as gene regulation, and some can even carry genes that provide advantageous traits, like antibiotic resistance, to bacteria. Other options listed refer to different genetic elements: plasmids are circular DNA molecules found in bacteria that replicate independently, introns are non-coding segments of a gene that are spliced out during RNA processing, and exons are the coding portions of a gene that are expressed into proteins. Each of these elements has distinct functions that do not involve the ability to "jump" within the genome as transposons do.