How many chromosomes are present in mouse somatic cells if the count is 40? - briefly
Mouse somatic cells have a diploid chromosome number of 40. This comprises 20 homologous chromosome pairs.
How many chromosomes are present in mouse somatic cells if the count is 40? - in detail
The diploid chromosome complement of a laboratory mouse (Mus musculus) consists of forty individual chromosomes. This number reflects 2 n = 40, where each autosomal chromosome is present in a homologous pair and the sex chromosomes complete the set.
- Autosomes: 19 pairs (38 chromosomes) arranged in decreasing size, with metacentric, submetacentric, and acrocentric morphologies.
- Sex chromosomes: one pair, either XX in females or XY in males, adding the final two chromosomes to reach the total of forty.
Each somatic cell contains one member of each homologous pair, ensuring that genetic information is present in duplicate. During mitosis, the chromosomes replicate, segregate, and maintain the 2 n = 40 count in daughter cells. In contrast, gametes undergo meiosis, producing haploid cells with n = 20 chromosomes.
The mouse karyotype is stable across most inbred strains, making it a standard reference for genetic studies. Chromosome sizes range from approximately 200 Mb for the largest autosome to about 10 Mb for the smallest, collectively encompassing roughly 2.7 Gb of genomic DNA. The sex chromosomes differ in size and gene content, with the Y chromosome being the smallest.
Thus, any mouse somatic cell that exhibits a diploid number of forty chromosomes contains the complete set of 19 autosomal pairs plus the appropriate sex chromosome pair.