How does Down syndrome occur?
Down syndrome results when abnormal cell division involving chromosome 21 occurs. These cell division abnormalities result in an extra partial or full chromosome 21. This extra genetic material is responsible for the characteristic features and developmental problems of Down syndrome.
How does Down syndrome occur in meiosis?
In translocation, a piece of chromosome or a whole chromosome breaks off during meiosis and attaches itself to another chromosome. The presence of an extra part of the number 21 chromosome causes the features of Down syndrome.
Which syndrome is also known as Trisomy 21 quizlet?
Also known as Down syndrome, trisomy 21 is a genetic condition caused by an extra chromosome. Most babies inherit 23 chromosomes from each parent, for a total of 46 chromosomes.
What stage of meiosis does Down syndrome occur?
DS results from nondisjunction (NDJ) of chromosome 21 during either of the two stages of meiosis, meiosis I (MI) or meiosis II (MII), or after the first few divisions (mitosis) of the embryo.
Is Down syndrome caused by mother or father?
There is no definitive scientific research that indicates that Down syndrome is caused by environmental factors or the parents’ activities before or during pregnancy. The additional partial or full copy of the 21st chromosome which causes Down syndrome can originate from either the father or the mother.
Can stress cause Down syndrome?
Down syndrome, which arises from a chromosome defect, is likely to have a direct link with the increase in stress levels seen in couples during the time of conception, say Surekha Ramachandran, founder of Down Syndrome Federation of India, who has been studying about the same ever since her daughter was diagnosed with …