For a species with a diploid number of 18, indicate how many chromosomes will be present in the somatic nuclei of individuals that are haploid, tetraploid, trisomic, and monosomic.

Verified step by step guidance

1. Identify the diploid number (2n) of the species, which is given as 18. This means the normal somatic cells have 18 chromosomes arranged in pairs.
2. Calculate the haploid number (n), which is half of the diploid number. Use the formula: \(n = \frac{2n}{2}\).
3. Determine the chromosome number in haploid individuals, which is simply the haploid number \(n\).
4. Calculate the chromosome number in tetraploid individuals, which have four sets of chromosomes. Use the formula: \$4n$.
5. For trisomic and monosomic individuals, start with the diploid number and then add or subtract one chromosome respectively. Use the formulas: trisomic = \$2n + 1\( and monosomic = \)2n - 1$.

Key Concepts

Diploid Number and Ploidy Levels

The diploid number (2n) represents the total chromosomes in somatic cells, with two sets from each parent. Haploid cells (n) have half this number, while polyploid cells like tetraploids have multiple sets (e.g., 4n). Understanding ploidy helps determine chromosome counts in different cell types.

Aneuploidy: Trisomy and Monosomy

Aneuploidy refers to the presence of an abnormal number of chromosomes. Trisomy means having one extra chromosome (2n + 1), while monosomy means missing one chromosome (2n - 1). These conditions alter chromosome counts from the normal diploid number.

Chromosome Counting in Somatic Cells

Somatic cells contain the full chromosome complement based on ploidy and aneuploidy status. Calculating chromosome numbers involves applying the ploidy level or aneuploid condition to the diploid number, enabling determination of chromosome counts in various genetic scenarios.