an adnormal number of chromosomes ofter results in
In one kind of abnormal chromosome inheritance called Down syndrome, a child has three copies of Chromosome 21!
chromosome 21
in anaphase 1 in myosis in old women (mostly) 21 chromosomes cant be separated and if this cell fertilizes the child will have three 21 chromosomes. that's why this disease is called trisomy of 21.
The unit of heredity found on a chromosome is called a gene.
Down syndrome is a result of having an extra chromosome in one's genes. Chromosome thirteen* if your that much into the science. It is also called trisomy 21 because the chromosome 21 is the one with the abnormalities. *Abnormalities with chromosome thirteen is called Patau syndrome or trisomy 13.
This pattern of inheritance is called X-linked inheritance. It involves genes located on the X chromosome, leading to different inheritance patterns in males (who have one X chromosome) and females (who have two X chromosomes).
Down syndrome occurs because of the extra chromosome on chromosome 21. If you go onto google images and type in karyotype of Down syndrome, you will find a picture of the extra chromosome. Instead of having two chromosomes on chromosome 21, there is an extra. Type your answer here...
Downs syndrome is in medical terms called Trisomy 21 as it is caused by a genetic defect in the 21st set of chromosome, usually you have 44 chromosomes - 22 from your mother and 22 from your father and a set of sex chromosomes (these are your male/female genes), if you have Down Syndrome you have an extra chromosome on the 21st set of genes so instead of 1 from each parent you have 1 from you dad, 1 from your mum and a mutated gene.
Patau syndrome, also known as Trisomy 13, is an abnormality of chromosomes in which a patient has an additional 13th chromosome due to a failure of chromosomes to split during meiosis. It can cause the following conditions: motor & mental retardation, extra digits, microcephaly, low-set ears, failure of the forbrain to divide properly, heart defects, eye defects, cleft palate, spinal defects, abnormal genitalia, abnormal palm patterns or overlapping of fingers over thumb. Photos of children with Patau Syndrome - Trisomy 13.
The gene associated with Marfan syndrome is located on chromosome 15. It is called the FBN1 gene, which provides instructions for making a protein called fibrillin-1. Mutations in this gene can lead to the characteristic features of Marfan syndrome.
Well down syndrome is causes by the 21st chromosome of a sex cell doubling, and so once fertilisation with the egg commences there will be 3 21st chromosomes. When you have 45 their is multiple things that can happen, the only consistent one is Turner Syndrome, which basically stunts puberty. This only happens in females and it is when they have X instead of XX.
Sex linked.