How similar is human DNA to rat DNA? - briefly
Human and rat genomes share approximately 85 % of their protein‑coding sequences, while overall genomic similarity—including non‑coding regions—is around 70 %. This degree of homology reflects a close evolutionary relationship between mammals.
How similar is human DNA to rat DNA? - in detail
The genomes of Homo sapiens and Rattus norvegicus share a high degree of sequence conservation. Whole‑genome alignments report approximately 85 percent nucleotide identity across orthologous regions. This figure rises to ≈ 90 percent within protein‑coding exons, reflecting strong selective pressure on functional elements.
Key aspects of the comparison include:
- Orthologous gene set: Roughly 13 000 genes are conserved as one‑to‑one orthologs, representing about 70 percent of the human protein‑coding repertoire.
- Conserved pathways: Core metabolic, signaling, and developmental pathways (e.g., MAPK, Wnt, insulin signaling) exhibit extensive sequence and structural similarity, facilitating translational studies.
- Regulatory regions: Promoter and enhancer sequences display lower conservation, typically 50‑70 percent identity, indicating species‑specific regulatory evolution.
- Repetitive elements: Rats possess a higher proportion of LINE‑1 and SINE retrotransposons, contributing to differences in genome size (≈ 2.8 Gb in rats vs. ≈ 3.2 Gb in humans).
Differences arise from divergent evolutionary pressures. Rats lack several gene families expanded in primates, such as the olfactory receptor repertoire, which is reduced in rodents. Conversely, rodents exhibit unique gene duplications involved in detoxification and immune response. Non‑coding RNA populations also vary, with rodents showing a greater abundance of certain microRNAs.
These genomic relationships underpin the extensive use of rats as model organisms in biomedical research. The substantial coding‑sequence similarity ensures that many pharmacological targets and disease mechanisms are conserved, while species‑specific variations must be accounted for when extrapolating findings to humans. Accurate interpretation of experimental data therefore relies on detailed knowledge of both shared and divergent genomic features.