Down's syndrome is an example of?

Question

a. an abnornal combination of chromosomes
b. the presence of two extra chromosomes
c. a faulty chromosome from the mother
d. an absence of the second sex chromosome

Answer 1

A
Downs syndrome is caused by three chromosomes of chromosome 21. It is known as trisomy 21. This chromosome is not a sex chromosome. (i.e. it's a somatic chromosome). There are three copies of the 21'st. chromosome instead of the normal two copies. (one from the father and one from the mother). That is one extra chromosome and not the two of answer B.
Doc. Dan.

Answer 2

B.....The presence of 2 extra chromosomes.
Down's Syndrome is formed by the addition of extra chromosomes to the regular amount. This accounts for the deformity or mental retardation in patients suffering from the genetic disorder........ although only one answer should be chosen, A also reflects some aspect of down's syndrome where the extra chromosome(s) present would cause an abnormal combination of chromosomes......

Answer 3

Down syndrome is a chromosomal abnormality characterized by the presence of an extra copy of genetic material on the 21st chromosome, either in whole (trisomy 21) or part (such as due to translocations). The effects of the extra copy vary greatly among individuals, depending on the extent of the extra copy, genetic background, environmental factors, and random chance. Down syndrome occurs in all human populations, and analogous effects have been found in other species such as chimpanzees and mice. With that said, "A" would be the best answer.

Answer 4

Technically, it's none of those, but 'a' is the closest. Down's Syndrome is the presence of an extra chromosome 21, which can come from either the mother or the father.

Answer 5

Bad question. Down's is usually considered trisomy 21, with just one extra copy of chromosome 21. Sometimes its also caused by key genes from chromosome 21 being translocated to another chromosome in addition to two normal 21s. So you can have Down's without technically having three 21's. That's why we also do FISH when diagnosing Down's, so we don' miss those.

Answer 6

The actual name for this condition is trisomy 21, which means that there is 1 extra copy of chromosome 21. In the normal cell there are only two copies of this chromosome. Therefore, none of your answers are specifically correct, but if i had to choose, then i would pick A.

Answer 7

Down syndrome is the disjunction of chromosomes or they fail to serparate and if this happens the person with Down syndome will have 47 chromosomes and not 46

Answer 8

down's syndrome is when there is an extra copy of the chromosome 21. so i guess that would be A.

Answer 9

a extra chromosome instead of 22, it is 23

Answer 10

it is A
it is due to the trisomy of the 21st pair.thus an abnormal condition of chromosomes.in the normal condition there are only 2 homologous chromosomes,one from each of the parent.