Lec. 20 - Meiosis Flashcards
Explain the process and steps of meiosis and the purpose.
Meiosis is a process that leads to the formation of haploid gametes with half the chromosome number of the parent cell. The stages are meiosis I, prophase I, metaphase I, anaphase I, telophase I, and cytokinesis. In meiosis II, it is prophase II, metaphase II, anaphase II, and telophase II, followed by cytokinesis II.
Compare sister chromatids and homologous chromosomes.
Sister chromatids are two identical copies of a single replicated chromosome joined together by a structure called the centromere. Homologous chromosomes are chromosome pairs that are similar in size shape, and genetic content.
Differentiate btwn. a zygote and a gamete.
Gametes are specialized sex cells that are haploid and contain half the number of chromosomes found in somatic cells in a diploid organism. Zygotes are a single diploid cell formed by the fusion of two haploid gametes during fertilization.
Compare mitosis and meiosis in relation to DNA and ploidy.
It mitosis, DNA replication occurs at the interphase preceding the division. Mitosis maintains the ploidy level of the parent cell. Meiosis involves two consecutive divisions after a single round of DNA replication. Meiosis reduces the chromosome number fro diploid to haploid by halving the number of chromosomes.
Describe why and where crossing over occurs.
It occurs during prophase I of meiosis. It introduces new allele combinations, contributes to genetic diversity, and creates genetically unique gametes.
