Meiosis and chromosome behavior
Homologous chromosomes carry the same gene loci but may carry different alleles. They pair during prophase I. Meiosis I reduces the number of homologous chromosome sets; after meiosis II, the products are haploid with unreplicated chromosomes. DNA is not normally replicated between the two divisions. Fertilization combines two haploid genomes and restores diploidy. Chromosome number, DNA amount, and number of cells must be tracked separately.
MAKE IT CONCRETE
If 2n = 10, each cell after meiosis I normally has 5 replicated chromosomes. After meiosis II, each product has 5 unreplicated chromosomes.
DON’T FALL FOR THIS
A sister chromatid is a copied chromosome component, not the homolog inherited from the other parent.