Interphase and Stages of Meiosis I
Meiosis begins with interphase, followed by the first round of division in Meiosis I. This process is crucial for reducing the chromosome number and creating genetic diversity.
Interphase: Before Meiosis I, the cell undergoes interphase, which includes G1, S, and G2 phases, similar to mitosis preparation. During this time, the cell grows and replicates its DNA.
Prophase I: This is the most complex phase of meiosis. Homologous chromosomes come together to form a synapse tetrad. Crossing over occurs, where portions of chromatids break off and attach to adjacent chromatids on the homologous chromosome, increasing genetic variability.
Highlight: Crossing over is a key process that contributes to genetic diversity among offspring.
Metaphase I: Homologous chromosomes line up randomly at the center of the cell in pairs. This process is called independent assortment and further contributes to genetic variation.
Vocabulary: Independent assortment refers to the random alignment of homologous chromosome pairs during metaphase I.
Anaphase I: Homologous chromosomes in the center of the cell are separated by spindle fibers from the centrioles. This separation is crucial for reducing the chromosome number.
Telophase I: Two nuclei form, each containing 23 duplicated chromosomes inhumans. This marks the end of the first meiotic division.
Definition: Haploid cells contain half the number of chromosomes as the original diploid cell.
Cytokinesis occurs after Telophase I, resulting in two unique haploid daughter cells, each with 23 chromosomes thoughtheyarestillduplicatedatthisstage.
