How many chromosomes does a rat somatic cell have? - briefly
A rat somatic cell has a diploid complement of 42 chromosomes, organized into 21 homologous pairs. This chromosome count is uniform across all non‑reproductive cells of the species.
How many chromosomes does a rat somatic cell have? - in detail
Rattus norvegicus somatic cells are diploid, containing 42 chromosomes (2 n = 42). The complement consists of 21 homologous pairs of autosomes and a pair of sex chromosomes: XX in females, XY in males.
The autosomal set includes:
- Six metacentric chromosomes (pairs 1–6)
- Four submetacentric chromosomes (pairs 7–10)
- Eleven acrocentric chromosomes (pairs 11–21)
Each chromosome pair carries a distinct banding pattern identifiable by G‑banding, enabling precise karyotyping. The total genomic DNA content approximates 2.75 gigabases per haploid genome, translating to roughly 5.5 gigabases in a somatic cell.
Chromosome number determination relies on metaphase spread preparation, colchicine treatment to arrest cells in mitosis, and subsequent staining. Standard laboratory rat strains (e.g., Sprague‑Dawley, Wistar) consistently display the 42‑chromosome complement, although long‑term cultured cell lines may acquire aneuploidy, typically gaining or losing one or more chromosomes.
The rat karyotype serves as a reference for genetic manipulation, disease modeling, and comparative genomics. Its stability across strains underpins reproducibility in biomedical research, while detailed knowledge of individual chromosome morphology aids in mapping disease‑related loci and assessing chromosomal abnormalities.