0
how could a zygote end up with an extra chromosome
Either the egg or the sperm doesn't divide equally.
David Macejkovic
Wiki User
∙ 9y agoPeople end up with extra or missing chromosomes as a result of mistakes during meiosis. Meiosis is the process that creates sperm and egg cells (aka gametes). When meiosis works perfectly, sperm and egg cells get the correct number of chromosomes. Sometimes, however, meiosis doesn't work quite right, leading to sperm or egg cells that don't have the right number. When these sperm or egg cells lead to a new organism, then the entire organism won't have the number of chromosomes.
- For humans, the typical number of chromosomes is 46. When a human makes egg or sperm cells, meiosis divides the chromosomes so that each sperm or egg cell gets just 23 chromosomes. That way, when a sperm and egg cell join together, the new cell (aka the zygote) will have 46 chromosomes again. That single cell divides by mitosis to make all the cells of the new person. If the zygote has 46 chromosomes, then all the cells of the person will have 46 chromosomes.
- Cells sort the 46 chromosomes carefully during meiosis. The 46 chromosomes represent 23 matching pairs of chromosomes. When a cell in the ovaries or testes is making eggs or sperm, it puts all the pairs together. Then, it pulls the pairs apart, so that one chromosome of each pair goes to a different gamete. This is how the number of chromosomes gets reduced from 46 to 23. Sometimes, however, something goes wrong, and both members of pair get put into the same gamete. So, you could have one egg cell with 24 chromosomes and one with 22. If this egg was fertilized with a sperm, the zygote that formed would have an extra chromosome. The zygote might be unable to survive or it might lead to a person with an unusual number of chromosomes, as is the case with people who have Down's syndrome.
Wiki User
∙ 10y agoIf the sperm or the egg don't divide equally. It's called fertilization when they join. The egg and the sperm come from two different organisms of the same species.
Wiki User
∙ 14y agoThe cells do not divide =ly
Glencoe Science book
Wiki User
∙ 14y agohow could a zygote end up with an extra chromosome
Either the egg or the sperm doesn't divide equally.
Wiki User
∙ 9y agoA zygote could end up with an extra chromosome when during meiosis the sperm or the cell does not divide equally. This may make the zygote have 24 chromosomes instead of 23.
Add your answer:
Earn +20 pts
Why is the number of chromosomes halved?
The normal cellular genetic complement number 2N is reduced to 1N in both of the sexual gametes so that when they recombine we end up with the standard chromosome number [1N + 1N = 2N] in our zygote.
Is A gene is a subunit of information within a chromosome?
Yes, it is!:)
Purpose of a telomere?
A telomere is the structure at each end of a chromosome. It consists of an area of highly repeated DNA combined with protein. Its main function is to protect the end of the chromosome.Telomeres are instrumental in enabling the cells to divide and replicate. But as we grow older these tips wear out and shorten much like the shoelace caps. When they get too short, we get diseases and die. The three Nobel Prize winners found this as they were looking for a cure for cancer.
Describe the chromatids that make up a chromosome when a cell is ready to divide?
Describe the chromatic that make up a chromosome when a cell is ready to split
Where do the 2 strands of the parent DNA end up in the daughter chromosome after DNA replication?
To simplify: the DNA molecule unzips and divides into 2 strands, then the replication makes the complements of each strand to make 2 full DNA daughter chromosomes, so half the parent DNA ends up in each daughter chromosome.
How could a zygote could end up with a extra chromosome?
how could a zygote end up with an extra chromosome Either the egg or the sperm doesn't divide equally.
Why is the number of chromosomes halved?
The normal cellular genetic complement number 2N is reduced to 1N in both of the sexual gametes so that when they recombine we end up with the standard chromosome number [1N + 1N = 2N] in our zygote.
How do you get nondisjunction?
You are born with it>>>>>>>>>>>During meiosis, chromosomes are separated equally. When they are notseparated equally - this is known as non-disjunction - the gametes end up with either an extra chromatid or no chromatid. In Down syndrome the offspring carries an extra chromatid in Chromosome 21, aka Trisomy 21
What is klien felter's syndrome?
Klinefelter's syndrome occurs when an extra x chromosome shows up in a male or an extra y show up in a female. Principal effects include hypogonadism and sterility.
Why do more males end up with sex-linked disorders?
More males than females end up with sex-linked disorders because of the y chromosome. It is shorter than the x-chromosome, and increases susceptibility to these problems.
How does non disjunction relate to the Down syndrome?
During meiosis, chromosomes are separated equally. When they are not separated equally - this is known as non-disjunction - the gametes end up with either an extra chromatid or no chromatid. In Down syndrome the offspring carries an extra chromatid in Chromosome 21, aka Trisomy 21.
What is considered aneuploid?
aneuploidy usually reslts from non-disjunction (failure to separate) of homologous chromosomes during meiosis (the creation of gametes). It results in an organism having the wrong number of a certain chromosome. The two most common forms are monosomy (only one chromosme eg. Turner syndrome) and trisomy (three of a chromosome eg Down and Klinefelter syndrome) from non-disjunction, the two chromosomes line up at the equater of a cell as an X, ready to separate, but it doesn't, this reults in one egg/sperm having 0 of a chromosome and another will have 2. If the one with 0 then forms a zygote with a normal egg/sperm the zygote could have only 1 chromosome -from the normal egg/sperm. If the one with 2 forms a zygote the zygote will have 3 of the chromosome, 2 from the mutated gamtete and 1 from the normal gamete.
Does a nondisjunction cause down syndrome?
During meiosis, chromosomes are separated equally. When they are not separated equally - this is known as non-disjunction - the gametes end up with either an extra chromatid or no chromatid. In Down syndrome the offspring carries an extra chromatid in Chromosome 21, aka Trisomy 21.
What chromosomal abnormality causes Down syndrome?
Down syndrome happens by the splitting of the chromosomes. It is not a genetic disease. It is a chromosomaldisorder.Chromosomal changes like duplications or translocations1 occur in only one sex cell. A baby normally inherits 23 chromosomes from each parent to make a total of 46 chromosomes in 23 identifiable pairs.In Down Syndrome, an extra (duplicated) chromosome number 21 is inherited from either the father or the mother, to make a total of 47 chromosomes (23 pairs plus 1) in every cell of the DS child. (DS is also called Trisomy 21 ) DS is usually inherited from the mother, and the major risk of DS is the age of the woman at conception.1A duplication is an extra copy of a chromosome (or part of a chromosome) - a translocation is an extra bit of chromosome sticking onto another chromosome.
What is larger a nucleosome or chromosome?
A chromosome is made up of many genes.
Where will extra fluid end up if you drink too much?
In the bladder, to be peed out.
Chromosome are made up of still smaller units called?
A chromosome is made up of DNA, which has subunits called nucleotides.
