Understanding:
• Diploid nuclei have pairs of homologous chromosomes
• Haploid nuclei have one chromosome of each pair
As sexually reproducing organisms receive genetic material from both parents, they have two sets of chromosomes (diploid)
To reproduce in turn, these organisms must create sex cells (gametes) with half the number of chromosomes (haploid)
When two haploid gametes fuse, the resulting diploid cell (zygote) can grow and develop into a new organism
Diploid
Nuclei possessing pairs of homologous chromosomes are diploid (symbolised by 2n)
- These nuclei will possess two gene copies (alleles) for each trait
- All somatic (body) cells in the organism will be diploid, with new diploid cells created via mitosis
- Diploid cells are present in most animals and many plants
Haploid
Nuclei possessing only one set of chromosomes are haploid (symbolised by n)
- These nuclei will possess a single gene copy (allele) for each trait
- All sex cells (gametes) in the organism will be haploid, and are derived from diploid cells via meiosis
- Haploid cells are also present in bacteria (asexual) and fungi (except when reproducing)
Haploid versus Diploid
