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How many chromosomes will a zygote with trisomy have?
Meiotic nondisjunction. In meiosis I or II, chromosome pair 21 fail to separate correctly, leaving one gamete with an extra chromosome 21.
What is trisomy mutation?
A trisomy is when a person has 3 versions of a chromosome. 'Normal' humans will only have 2 of each chromosome. For example, having 3 versions of chromosome 21 is known as Trisomy 21 or Down Syndrome.
Is thalassemia sex-linked trait?
Down syndrome results from a nondisjunction during cell division. That is, homologous chromosomes 21 fail to separate in meiosis I, or sister chromatids 21 during meiosis II or mitosis. Down syndrome is caused by trisomy of chromosome 21 (an extra chromosome to the usual two), which is an autosomal chromosome. Therefore it is not a sex linked disorder.
Many chromosome mutations result when chromosomes fail to separate properly during what?
Meiosis, specifically during anaphase I and anaphase II. This is known as nondisjunction and it causes aneuploidy, such as trisomy 21
What are nondisjunction genes?
Nondisjunction is the failure of homologous chromosomes or chromatids to segregate during mitosis or meisos with the result that one daughter cell has both of a pair of parental chromosomes or chromatids and the other has none. An example is Trisomy 21, which is also called Down's Syndrome. This person has 3 chromosome #21.Nondisjunction of genes occur during meiosis I when homologous chromosomes fail to separate or during meiosis II when there is unequal distribution of chromosomes. This leads to aneuploidy.
How many chromosomes will a zygote with trisomy have?
Meiotic nondisjunction. In meiosis I or II, chromosome pair 21 fail to separate correctly, leaving one gamete with an extra chromosome 21.
What stage of cell division would down's syndrome occur?
Down syndrome (trisomy 21) occurs when a gamete carrying an extra copy of chromosome 21 is involved in a fertilization event.The gamete (whether sperm or oocyte) has an extra copy of chromosome 21 because of something called NONDISJUNCTION. This happens when a chromosome gets pulled to the wrong daughter cell.This can happen either in meiosis I or meiosis II.If nondisjunction happens in meiosis I, 2 gametes will be n+1 (have the extra copy of 21) and the other 2 gametes will be n-1 (will have NO copy of 21)If nondisjunction happens in meiosis II, 2 gametes will be normal, one will be n+1 and one will be n-1.
What is trisomy mutation?
A trisomy is when a person has 3 versions of a chromosome. 'Normal' humans will only have 2 of each chromosome. For example, having 3 versions of chromosome 21 is known as Trisomy 21 or Down Syndrome.
Is thalassemia sex-linked trait?
Down syndrome results from a nondisjunction during cell division. That is, homologous chromosomes 21 fail to separate in meiosis I, or sister chromatids 21 during meiosis II or mitosis. Down syndrome is caused by trisomy of chromosome 21 (an extra chromosome to the usual two), which is an autosomal chromosome. Therefore it is not a sex linked disorder.
What happens when Nondisjuntion during meiosis at the 21 chromosome?
The most common deffect that will occur with there is nondisjunction on the 21st chromosome is downs syndrome. Downs syndrome is a mental illness that can cause some physical abnormalities such as a large forhead, but also some intellectual delays.
Many chromosome mutations result when chromosomes fail to separate properly during what?
Meiosis, specifically during anaphase I and anaphase II. This is known as nondisjunction and it causes aneuploidy, such as trisomy 21
What are nondisjunction genes?
Nondisjunction is the failure of homologous chromosomes or chromatids to segregate during mitosis or meisos with the result that one daughter cell has both of a pair of parental chromosomes or chromatids and the other has none. An example is Trisomy 21, which is also called Down's Syndrome. This person has 3 chromosome #21.Nondisjunction of genes occur during meiosis I when homologous chromosomes fail to separate or during meiosis II when there is unequal distribution of chromosomes. This leads to aneuploidy.
How are cells of a person with Down syndrome different from those of a person without the disorder?
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.
What might happen if human chromosomes did not separate?
well if human chromosomes number 21 does not separate during fertilization the baby will be with down syndrome. at fertilization of the egg with a normal sperm the zygote contain three chromosome number 21 (trizomic 21) hence the zygote contain 47 chromosome instead of 46.
Is down syndrome a single gene disorder?
People with Down syndrome have an extra copy of chromosome 21 in every cell. Down syndrome most often occurs when chromosomes fail to separate properly during meiosis, when sex cells form. Hope this helps!!
What process takes place when a chromosome pair fails to separate correctly during meiosis?
When chromosome pairs fail to separate aneuploidy occurs due to non-disjunction. This can result in monosomy or trisomy of the chromosome. These are mistakes made in chromosome segregation during meiosis. If pairs of homologous chromosomes fail to separate during the first meiotic division or if the centromere joining sister chromatids fails to separate during the second meiotic division, gametes, and hence offspring, will be produced that have too many and too few chromosomes.If this occurs in a cell of the body that is undergoing mitosis, the body will destroy the cell. If it occurs in a gametic cell (ovum or sperm) then the result can be trisomy, which is when the offspring receives three of the same chromosome rather than the normal two. Often the embryo will abort itself if this occurs but if you end up with three copies of chromosome 21 this is known as down syndrome. One the creation of a cell with trisomy, another cell results that is missing the chromsome so it is possible to end up with gametes missing a chromosome aswell, which will usuallr cause the embryo to abort, or may lead to serious defects in the offspringThe tetrads (pairs of homologous chomosomes) split up during Anaphase I in Meiosis I.
Does Down syndrome occur in a specific location?
Down Syndrome is known as trisomy 21 because someone with the syndrome has 3 chromosomes of the same type when we are only supposed to have 2 (one from each parent). Chromosomes are paired and numbered so Down Syndrome is the result of having 3 of the #21 chromosome. The body will not know what to do with the extra chromosome so as a precautionary measure it will shut down all 3 and the genes that are within the chromosomes can no longer be accessed. So as you can see, Down Syndrome is not from being inherited by a specific gene. It is due to an error in meiosis in either the mother or the father.
