Question

BI119. Homework - Mitosis/Meiosis Name: Brittany Helman 1. (7pts) Compare and contrast Mitosis -vs- Melosis by filling in the chart. (Don't forget to indicate the correct choice asked in the brackets!) Mitosis Meiosis # Parent cell 1 parent cell 1 parent cell diploid (2n) (haploid(n) or diploid(2n)?] haploid (n) Location of cell division (germ-line cells or somatic cells?] Purpose/Function [repair, growth, gamete production, asexual reproduction, sexual reproduction? Sonratc cells repair germ-line cells gamate produchon sexual reproduction growth a sexual reproducha # Daughter cells In or 2n?) an identical [Identical or Different?] different # of time(s) DNA is replicated? I once Once #of time(s) cytokinesis occurs? twice 2. (3pts) List three (3) ways sexual reproduction and fertilization increases genetic diversity. Don't forget to include where they occur within meiosis or fertilization.

Answer 1

a. Crossing over: During Prophase-I, the homologous pair of chromosomes bind with each other via synapsis producing a tetrad. Later a crossing-over event occurs between the non-sister chromatids, during which they exchange chromosome segment. This exchange/ recombination creates genetic variation. Such crossing-over events occur all over the chromosome creating unique germ cells/gametes.

b. Independent Assortment: During Metaphase-I, after the crossing-over, the tetrads get arranged linearly at the metaphase plate randomly and the spindle fibers from each pole attach to one of the homolog of the tetrad. During Anaphase-I, the homologs are pulled apart towards the poles. Due to this random assortment of homologous chromosomes during metaphase-I creates genetic diversity.

c. Fertilization; The fusion of male and female gametes is known as fertilization. It is a major process to introduce genetic variation. Each parent contributing a random set of chromosomes which combine to create a diploid zygote.