Answer :
Final answer:
The sequence that led to one twin having a normal genotype and the other twin having trisomy 13 would be Fertilization, Meiosis, and Nondisjunction. Fertilization occurs first to create the zygote, which splits into two embryos. An error in meiosis leads to nondisjunction and the creation of an extra chromosome 13 in one of the twins, resulting in trisomy 13.
Explanation:
In the case of monozygotic twins where one has a normal genotype (46, XY) and the other has trisomy 13 (47, 13), the sequence of events would be: Fertilization, Meiosis, Nondisjunction.
Fertilization takes place first, uniting a sperm and an egg to create a single cell called a zygote. The zygote then divides by mitosis where its chromosomes duplicate correctly, resulting in a normal genotype twin.
Simultaneously, meiosis- a cell division process that happens in creating sex cells - can lead to errors when chromosomes do not separate properly which is known as nondisjunction. Here, an error occurred resulting in one of the twins possessing an extra chromosome (#13) creating a condition called trisomy 13.
Trisomy is a chromosomal disorder where an individual has an additional copy of a chromosome, in this case chromosome 13. It's important to note that trisomy is not caused by mutations in genes, but rather by the presence of extra chromosomes due to nondisjunction events during meiosis.
Learn more about Trisomy 13 here:
https://brainly.com/question/35580125
#SPJ11
