Nondisjunction during either meiosis I or II can produce a gamete that will result in a trisomic zygote. Since the incidence of Down syndrome increases with maternal age, it is likely that this error occurs in the female gamete. Females with only one X chromosome do not develop; this condition is lethal.
What is the result of nondisjunction during meiosis?
Nondisjunction in meiosis can result in pregnancy loss or birth of a child with an extra chromosome in all cells, whereas nondisjunction in mitosis will result in mosaicism with two or more cell lines. Aneuploidy may also result from anaphase lag.
Which of the following could result from nondisjunction?
Nondisjunction causes errors in chromosome number, such as trisomy 21 (Down syndrome) and monosomy X (Turner syndrome). It is also a common cause of early spontaneous abortions.
What is the outcome of nondisjunction in meiosis I quizlet?
Nondisjunction in meiosis I results from failure of homologs to separate; the gametes produced are either n+1 or N-1.
What happens during meiosis to produce an aneuploid?
What happens during meiosis to produce an polyploid? DNA replicates, but is not apportioned into daughter cells, forming a diploid gamete. … Crossing over in the male yields unbalanced gametes, which can fertilize oocytes, but too much or too little genetic material halts development.
How nondisjunction can result in an aneuploid zygote?
Explain how nondisjunction can lead to aneuploidy. Nondisjunction is a situation where a pair of homologous chromosomes fails to separate during meiosis I or meiosis II. Failure to separate causes aneuploidy which is a condition where a zygote will have an abnormal amount of chromosome.
What is an example of nondisjunction?
This could result to a condition wherein the daughter cells have an abnormal number of chromosomes; one cell having too many chromosomes while other cell having none. Examples of nondisjunction: Down syndrome. Triple-X syndrome. Klinefelter’s Syndrome.
How do nondisjunction errors in meiosis lead to aneuploidies such as trisomies and Monosomies?
Aneuploidy is caused by nondisjunction, which occurs when pairs of homologous chromosomes or sister chromatids fail to separate during meiosis. The loss of a single chromosome from a diploid genome is called monosomy (2n-1), while the gain of one chromosome is called trisomy (2n+1).
Which answer option occurs during anaphase I of meiosis?
The correct option is the homologous pairs separate and move to each pole.
What is a possible result of nondisjunction quizlet?
Nondisjunction. An error in meiosis in which cromosomes fail to separate and a gamete with too many or too few copies of a particular chromosome can be produced.
What happens during meiosis I and meiosis II?
In meiosis I, homologous chromosomes separate, while in meiosis II, sister chromatids separate. Meiosis II produces 4 haploid daughter cells, whereas meiosis I produces 2 diploid daughter cells. Genetic recombination (crossing over) only occurs in meiosis I.
What three processes occur during meiosis?
Three Ways that Genetic Diversity Occurs During Meiosis
- Meiosis I and II. Meiosis occurs over two generations of cells. …
- Crossing Over. …
- Reduction to Haploid. …
- Random Chromatid Assortment. …
What happens in prophase of meiosis?
During prophase I, the complex of DNA and protein known as chromatin condenses to form chromosomes. … A large structure called the meiotic spindle also forms from long proteins called microtubules on each side, or pole, of the cell. Between prophase I and metaphase I, the pairs of homologous chromosome form tetrads.
How does Nondisjunction lead to aneuploidy?
Nondisjunction in meiosis II results from the failure of the sister chromatids to separate during anaphase II. Since meiosis I proceeded without error, 2 of the 4 daughter cells will have a normal complement of 23 chromosomes. The other 2 daughter cells will be aneuploid, one with n+1 and the other with n-1.