Nondisjunction.
This is a type of mutation called translocation.
This process is called meiosis.
In animal cells (meiosis) the parent (which is a diploid cell with homologous pairs of chromosomes) seperates into two daughter cells containing the replicated pairs of sister chromatids. The process of meiosis is begun again (meiosis II) from which the sister chromatids separate into individual chromosomes. Then, the two diploid cells separate into 4 haploid daughter cells containing 1 chromosome. This is a generalized answer without the steps of meiosis described.
Chromosome pairs undergo a process called meiosis during which they are divided. One of the pairs, known as the sex chromosomes, determines the sex of an individual. In humans, females have two X chromosomes, while males have one X and one Y chromosome. These sex chromosomes are distributed randomly to sex cells during meiosis, resulting in the formation of eggs (in females) and sperm (in males) with varying combinations of sex chromosomes.
Its called disconjunction. Sometimes it is so bad that they have a miscarriage or the following happens:Trisomy (extra chromosomeso have 47 chromosomes instead of 46)Down's syndrome (andextra number 21 chromosome)Klinefelter's syndrome (males with an extra X chromosome...XXY)
Nondisjunction
Meiosis does in fact divide twice, once in meiosis I (cytokinesis) and meiosis II (cytokinesis) basically it divides into four daughter cells at the end of meiosis. Two from meiosis I and four in meiosis II
This is a type of mutation called translocation.
This change is know as polyploidy.
This process is called meiosis.
Nondisjunction- is the failure of chromosome pairs to separate properly during cell division. This could arise from a failure of homologous chromosomes to separate in meiosis I, or the failure of sister chromatids to separate during meiosis II or mitosis. The result of this error is a cell with an imbalance of chromosomes. When a single chromosome is lost (2n-1), it is called a monosomy, in which the daughter cell(s) with the defect will have one chromosome missing from one of its pairs. When a chromosome is gained, it is called trisomy, in which the daughter cell(s) with the defect will have one chromosome in addition to its pairs.The word nondisjunction means "not coming apart". Examples of nondisjunction: Down syndrome, Triple-X syndrome, Klinefelter's Syndrome, Turner's Syndrome
Meiosis reduces the number of chromosome sets from two (diploid), to one (haploid). In mitosis the daughter cells are genetically identical to the parent cell, but meiosis produces cells that differ genetically from the parent cell as well as each other. In the final stage of meiosis II there end up being 4n daughter cells. So remember mitosis is diploid and meiosis is haploid.
In animal cells (meiosis) the parent (which is a diploid cell with homologous pairs of chromosomes) seperates into two daughter cells containing the replicated pairs of sister chromatids. The process of meiosis is begun again (meiosis II) from which the sister chromatids separate into individual chromosomes. Then, the two diploid cells separate into 4 haploid daughter cells containing 1 chromosome. This is a generalized answer without the steps of meiosis described.
Chromosome pairs undergo a process called meiosis during which they are divided. One of the pairs, known as the sex chromosomes, determines the sex of an individual. In humans, females have two X chromosomes, while males have one X and one Y chromosome. These sex chromosomes are distributed randomly to sex cells during meiosis, resulting in the formation of eggs (in females) and sperm (in males) with varying combinations of sex chromosomes.
Homologous chromosomes (also called homologs or homologues) are chromosome pairs of approximately the same length, centromere position, staining pattern, with genes for the same characteristics at corresponding loci. In meiosis I, the chromosomes are duplicated first then the homologous pairs separate together. Sections of the DNA can sometimes cross over between homologous pairs. Later, during Meiosis II, these pairs are separated into the gametes with only one of each pair. If you said there was only one chromosome, you are thinking of the final result of meiosis.
Its called disconjunction. Sometimes it is so bad that they have a miscarriage or the following happens:Trisomy (extra chromosomeso have 47 chromosomes instead of 46)Down's syndrome (andextra number 21 chromosome)Klinefelter's syndrome (males with an extra X chromosome...XXY)
A nucleus is signals the rest of the cell that the cell is ready to undergo meiosis, in which case the chromosomes begin to condense with the help of histones, which is the beginning of prophase I of meiosis.