DRAW IT The diagram shows a cell in meiosis. a. Label the appropriate structures with these terms: chromosome (label as duplicated or unduplicated), centromere, kinetochore, sister chromatids, nonsister chromatids, homologous pair (use a bracket when labeling), homolog (label each one), chiasma, sister chromatid cohesion, and gene loci, labeling the alleles of the F and H genes.

Key Concepts

Meiosis

Meiosis is a specialized type of cell division that reduces the chromosome number by half, resulting in four genetically diverse gametes. It consists of two sequential divisions: meiosis I, where homologous chromosomes are separated, and meiosis II, where sister chromatids are separated. This process is crucial for sexual reproduction and contributes to genetic variation through mechanisms like crossing over.

Chromosomes and Chromatids

Chromosomes are structures made of DNA and protein that carry genetic information. During meiosis, chromosomes are duplicated, resulting in two sister chromatids joined at a region called the centromere. Understanding the distinction between unduplicated (single) and duplicated (two sister chromatids) chromosomes is essential for labeling diagrams accurately during meiosis.

Genetic Variation and Alleles

Genetic variation arises from the different forms of genes known as alleles, which can be located at specific positions called gene loci on chromosomes. During meiosis, processes like crossing over at chiasmata allow for the exchange of genetic material between nonsister chromatids, leading to new combinations of alleles in gametes. This variation is fundamental for evolution and adaptation in populations.