The Reduction of Chromosome Number in Meiosis Is Determined by Properties Built into the Chromosomes. In meiosis I, two chromatids move to each spindle pole. Then, in meiosis II, the two are distributed, one to each future gamete. This requires that meiosis I chromosomes attach to the spindle differently than meiosis II chromosomes and that they regulate chromosome cohesion differently. We investigated whether the information that dictates the division type of the chromosome comes from the whole cell, the spindle, or the chromosome itself. Also, we determined when chromosomes can switch from meiosis I behavior to meiosis II behavior. We used a micromanipulation needle to fuse grasshopper spermatocytes in meiosis I to spermatocytes in meiosis II, and to move chromosomes from one spindle to the other. Chromosomes placed on spindles of a different meiotic division always behaved as they would have on their native spindle; e.g., a meiosis I chromosome attached to a meiosis II spindle in its normal fashion and sister chromatids moved together to the same spindle pole. We also showed that meiosis I chromosomes become competent meiosis II chromosomes in anaphase of meiosis I, but not before. The patterns for attachment to the spindle and regulation of cohesion are built into the chromosome itself. These results suggest that regulation of chromosome cohesion may be linked to differences in the arrangement of kinetochores in the two meiotic divisions.
No.
Chromosome replication occurs before both mitosis and meiosis. During the S phase of the cell cycle, DNA is replicated in preparation for cell division. In mitosis, replicated chromosomes are separated into two identical daughter cells, while in meiosis, replicated chromosomes are separated twice to produce haploid gametes.
Tetrads only appear in meiosis. The tetrad is the joining of four chromosomes in prophase I of meiosis. Two male duplicated chromosomes and two female chromosomes. The most important role of tetrad formation is ' crossing over. ' This is the exchange of genetic information between the male and female chromosomes. The material, whole genes, is physically swapped between the male and female chromosomes.
its haploid= 4 cellsBy the end of meiosis all four resulting daughter cells are haploid.
Chromosomes replicate during the S phase of interphase, before meiosis begins. This ensures that each chromosome consists of two sister chromatids, which are then separated during the meiotic divisions to produce haploid cells.
Meiosis is divided into Meiosis I and Meiosis II because the initial cell divides twice producing four genetically different sex cells (gametes) Each time a cell divides, it goes through Prophase, Metaphase, Anaphase, and Telophase. See the link below for a diagram showing the process.
Autopolyploidy is a speciation process that begins with an event during which an organism has extra sets of chromosomes derived from the same species. This can occur through mechanisms such as whole genome duplication. These additional sets of chromosomes can lead to reproductive isolation and eventually result in the formation of a new species.
The Reduction of Chromosome Number in Meiosis Is Determined by Properties Built into the Chromosomes. In meiosis I, two chromatids move to each spindle pole. Then, in meiosis II, the two are distributed, one to each future gamete. This requires that meiosis I chromosomes attach to the spindle differently than meiosis II chromosomes and that they regulate chromosome cohesion differently. We investigated whether the information that dictates the division type of the chromosome comes from the whole cell, the spindle, or the chromosome itself. Also, we determined when chromosomes can switch from meiosis I behavior to meiosis II behavior. We used a micromanipulation needle to fuse grasshopper spermatocytes in meiosis I to spermatocytes in meiosis II, and to move chromosomes from one spindle to the other. Chromosomes placed on spindles of a different meiotic division always behaved as they would have on their native spindle; e.g., a meiosis I chromosome attached to a meiosis II spindle in its normal fashion and sister chromatids moved together to the same spindle pole. We also showed that meiosis I chromosomes become competent meiosis II chromosomes in anaphase of meiosis I, but not before. The patterns for attachment to the spindle and regulation of cohesion are built into the chromosome itself. These results suggest that regulation of chromosome cohesion may be linked to differences in the arrangement of kinetochores in the two meiotic divisions.
No.
24.This is because in chimpanzees, as in humans, the gametes (eggs and sperms) are formed by the type of division called meiosis. During meiosis, the number of chromosomes is halved.
Chromosome replication occurs before both mitosis and meiosis. During the S phase of the cell cycle, DNA is replicated in preparation for cell division. In mitosis, replicated chromosomes are separated into two identical daughter cells, while in meiosis, replicated chromosomes are separated twice to produce haploid gametes.
Tetrads only appear in meiosis. The tetrad is the joining of four chromosomes in prophase I of meiosis. Two male duplicated chromosomes and two female chromosomes. The most important role of tetrad formation is ' crossing over. ' This is the exchange of genetic information between the male and female chromosomes. The material, whole genes, is physically swapped between the male and female chromosomes.
Chromosomal exchange, or crossing over, is important during meiosis because it promotes genetic diversity among offspring. This process shuffles genetic material between homologous chromosomes, leading to new combinations of genes. This increases variation within a population, which can enhance the ability of a species to adapt to changing environments.
NO light microscope can not magnify the image to see chromosomes. You can see with fluorescence microscopes to observe them during cell cycle. Light microscope is helpful to check the whole living cell.
its haploid= 4 cellsBy the end of meiosis all four resulting daughter cells are haploid.
Remember that meiosis occurs during the production and maturation of gametes so it occurs very often! In males, it occurs virtually throughout their whole life and in females, meiosis I completes at every ovulatory cycle until menopause and meiosis II completes with fertilization.