chikcen and rice
It is the failure of chromosome pairs to separate properly during cell division.
Segregation of alleles occurs during meiosis, specifically during the separation of homologous chromosomes in anaphase I. This process ensures that each gamete receives only one copy of each gene, leading to genetic diversity in offspring.
Since gametes divide by a special process, meiosis, they will always have half the number of chromosomes as regular body cells. This is because the chromosomes only copy themselves once, however they are split apart twice. Think of it as a math problem. If the original cell count is, for example, 2 chromosomes, and each chromosome makes a copy of itself, the cell will have 4 chromosomes. During meiosis 1, the cell divides, and the chromosomes split, resulting in each daughter cell having 2 chromosomes, the same as the original. However, in meiosis 2, they divide again without making another copy of themselves, so that by the time meiosis is done, each one of the 4 cells that results have 1 chromosome, half the number of the original cell. 2x2=4 4/2=2 2/2=1
The chromosomes split equally and move to the opposite sides of the cell.
During meiosis, segregation occurs when homologous pairs of chromosomes separate and move to opposite poles during the first division of meiosis. This process ensures that each resulting gamete receives only one copy of each chromosome, leading to genetic diversity in offspring.
It is the failure of chromosome pairs to separate properly during cell division.
Meiosis
technically the chromosomes copy during interphase right before metaphase I of meiosis I so during Meiosis I the chromosomes are duplicated and not until metaphase II during meiosis II are the sister chromatids separated.
Mistakes in meiosis may cause Down syndrome. The error happens when the chromosomes segregate into the gametes. The egg or sperm may have too many or too few chromosomes. Down syndrome has an extra chromosome in the 21st pair.
Segregation of alleles occurs during meiosis, specifically during the separation of homologous chromosomes in anaphase I. This process ensures that each gamete receives only one copy of each gene, leading to genetic diversity in offspring.
Nondisjunction is a process during cell division where chromosomes fail to separate correctly. In Trisomy 21, an individual has three copies of chromosome 21 instead of the usual two, which is caused by nondisjunction during either meiosis I or meiosis II in the formation of gametes. When a gamete with an extra copy of chromosome 21 is fertilized, it results in an individual with Down syndrome.
Chromosomes are duplicated during the S phase of the cell cycle, which occurs before cell division. This process ensures each daughter cell receives a complete set of chromosomes. Duplication involves making an identical copy of each chromosome, including its genes and DNA.
Since gametes divide by a special process, meiosis, they will always have half the number of chromosomes as regular body cells. This is because the chromosomes only copy themselves once, however they are split apart twice. Think of it as a math problem. If the original cell count is, for example, 2 chromosomes, and each chromosome makes a copy of itself, the cell will have 4 chromosomes. During meiosis 1, the cell divides, and the chromosomes split, resulting in each daughter cell having 2 chromosomes, the same as the original. However, in meiosis 2, they divide again without making another copy of themselves, so that by the time meiosis is done, each one of the 4 cells that results have 1 chromosome, half the number of the original cell. 2x2=4 4/2=2 2/2=1
In Down syndrome, a person's cells have an extra copy of chromosome 21. In other words, instead of a pair of chromosomes, a person with Down syndrome has three of that chromosome. Down syndrome most often occurs when chromosomes fail to separate properly during meiosis. People with Down syndrome have a degree of mental retardation. Heart defects are also common, but can be treated.
opposite poles of the cell, ensuring that each gamete receives only one copy of each chromosome. This is important for maintaining the correct number of chromosomes in the offspring.
Crossing over begins early in prophase I of meiosis. At the time, homologous chromosomes Are paired along their lengths. Each gene on one homologue ia alined precisely with the corresponding gene on the other homologue. Source: my science book copy right 2006
Chromosomes carry genetic information, which is passed on during the cell division process of meiosis. Meiosis involves two rounds of cell division that result in the formation of gametes (sperm and egg cells) with half the number of chromosomes as the parent cell, allowing for genetic diversity through the random assortment of chromosomes.