A Occurs When Only One Member Of Each Homologous Pair Of Chr
A Occurs When Only One Member Of Each Homologous Pair Of Chromosome
A Occurs When Only One Member Of Each Homologous Pair Of Chromosome
A. Occurs when only one member of each homologous pair of chromosomes is present
B. Nuclear membrane re-forms
C. Chromosomes align in the middle of the meiosis II cell
D. DNA replicates
E. Crossing over occurs during this phase
F. The centromeres split and the chromatids are pulled apart
G. DNA condenses into chromosomes
H. Chromatids separate in a meiosis II cell
I. RNA leaves the nucleus
J. Four daughter cells form, each with one copy of the original chromosomes
K. Chromosomes align along the middle of the cell
L. The cell splits into two daughter cells
Cleaned Assignment Instructions:
Identify the phase of meiosis that occurs when only one member of each homologous pair of chromosomes is present, based on the given options and descriptions, including key events listed such as chromosome alignment, separation, crossing over, and cell division stages.
Paper For Above instruction
The process of meiosis is fundamental to sexual reproduction, ensuring genetic diversity and the proper distribution of chromosomes to gametes. Within this process, several distinct phases occur, each with specific cellular events and characteristics. Among these, the phase where only one member of each homologous chromosome pair is present corresponds to the reduction of chromosome number and is critical for forming haploid cells. This phase is known as meiosis I, specifically during anaphase I when homologous chromosomes are separated, leaving only one chromosome from each pair in the daughter cells.
Introduction to Meiosis and Chromosome Reduction
Meiosis is a specialized cell division process that results in four haploid gametes from an original diploid germ cell. It consists of two sequential divisions: meiosis I and meiosis II. The primary goal of meiosis I is to reduce the chromosome number by half, which is achieved by segregating homologous chromosomes into separate daughter cells. During this phase, homologous pairs—each consisting of two sister chromatids—pair up during prophase I, undergo crossing over, and align at the metaphase plate.
Key Phases Relevant to the Question
The phase in question, where only one homologous chromosome from each pair remains, occurs after the separation of homologs. This corresponds to anaphase I in meiosis I, wherein homologous pairs are pulled apart toward opposite poles of the cell, leaving each daughter cell with a haploid set of chromosomes. At this stage, the cell transitions from metaphase I, where chromosomes are aligned at the metaphase plate, to anaphase I, characterized by the movement of homologous chromosomes to opposite poles. This division reduces the chromosome number to haploid—meaning only one member of each homologous pair is present in the resulting cells.
Distinguishing the Phases in Context
A critical aspect of understanding meiosis involves recognizing the key events:
- Prophase I: Chromosomes condense, crossing over occurs, and homologous pairs pair up.
- Metaphase I: Homologous pairs align along the middle of the cell.
- Anaphase I: Homologous chromosomes separate and move to opposite poles.
- Telophase I and Cytokinesis: The cell divides into two haploid cells, each with a set of chromosomes still composed of sister chromatids.
In relation to the options provided, the phase where one chromosome of each homologous pair is present—signifying reduction to haploid—is Anaphase I. The key event here is the splitting of homologous chromosomes, which results in each daughter cell containing one member of each pair.
Other Phases and Their Characteristics
- Interphase involves DNA replication, preparing the cell for division.
- Prophase involves chromosome condensation and crossing over.
- Metaphase aligns chromosomes at the cell's midline.
- Anaphase II and telophase II refer to the second meiotic division, where sister chromatids separate, resulting in haploid gametes.
- Cytokinesis is the physical division of the cytoplasm, forming separate daughter cells.
Conclusion
Given the description and options, the best match for the phase when only one member of each homologous pair of chromosomes is present is Anaphase I. This stage ensures reduction in chromosome number necessary for haploid gamete formation, maintaining genetic diversity and the integrity of genetic information across generations.
References
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