Question

Choose the phase of meiosis in column 2 that best matches each event in column 1. - one haploid set of replicated chromosomes at each spindle pole - genetic recombination events take place - shortest stage - aligning of bivalents in the center of a spindle - one haploid set of unreplicated chromosomes at each spindle pole - aligning of monovalents in the center of a spindle - separation of homologous chromosomes - separation of sister chromatids A. telophase II B. anaphase I C. metaphase I D. prophase II E. anaphase II F. telophase I G. metaphase II H. prophase I

Answer 1

Answer:

H. prophase I → genetic recombination events take place

C. metaphase I → aligning of bivalents in the center of a spindle

B. anaphase I → separation of homologous chromosomes

F. telophase I → one haploid set of replicated chromosomes at each spindle pole

D. prophase II → shortest stage

G. metaphase II → aligning of monovalents in the center of a spindle

E. anaphase II → separation of sister chromatids

A. telophase II → one haploid set of unreplicated chromosomes at each spindle pole

Explanation:

Through the process of Meiosis, a diploid germ cell (2n) divides and originates four daughter cells with a haploid chromosome number (n). Each daughter cell has half of the chromosomes of the original one. Meiosis is completed in two phases. During the first phase, and after replication, occurs the chromosome´s reduction division. During the second phase, the cell suffers a new, not reductive division.

1. In the first phase, Meiosis I:

• Prophase I: Chromosomes condensate and became visible. Occurs crossing-over between homologous chromosomes. Crossin-over makes the daughter cells to be genetically different from the original one.
• Metaphase I: The pairs of homologous chromosomes randomly align in the equatorial plane.
• Anaphase I: occurs the independent separation of homologous chromosomes that migrate to opposite poles of the cell. This separation generates different chromosomal combinations in the daughter cells.
• Telophase I: Each of the homologous pairs chromosomes is already in the corresponding poles, and the nuclear membrane forms again in each pole.

2. In the second phase, Meiosis II:

• Prophase II: Chromosomes condensate again and become visible.
• Metaphase II: Chromosomes join the spindle apparatus and migrate to the equatorial plane, where they randomly line up. Sister chromatids are holden together until they reach the Anaphase.
• Anaphase II: Centromeres divide, chromatids get separated, and each of them goes forward an opposite cellular pole.
• Telophase II: Once in the poles, the chromosomes became lax again, and cytokinesis occurs.