AAMC FL Practice Exam

What does the presence of introns suggest about an organism?

1. It is a prokaryote

2. It is a virus

3. It is a eukaryote

4. It cannot reproduce

The correct answer is: It is a eukaryote

The presence of introns in an organism's DNA is a significant indicator of eukaryotic organisms. Introns are non-coding sequences that are found within genes and are spliced out during the process of mRNA maturation. Eukaryotes, which include organisms such as plants, animals, fungi, and protists, have complex cellular structures that allow for such intricate gene regulation and mRNA processing. In contrast, prokaryotes, which include bacteria and archaea, typically have fewer introns, and many of their genes are arranged in operons, where multiple genes are transcribed together. Viruses do not generally have the same type of intron-containing genes, as their genetic material is often composed of either RNA or DNA in a more compact form that lacks the complexity of intron-exon structure found in eukaryotic genes. The presence of introns does not relate to an organism's ability to reproduce, as many eukaryotes have diverse reproductive strategies. Thus, the correct interpretation of the presence of introns is that it strongly suggests the organism in question is a eukaryote.