OBJECTIVE LIFE SCIENCE
GENETICS
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
Sister chromatids do not align in metaphase I.
|
|
|
Homologous chromosomes do not separate in anaphase I.
|
|
|
Sister chromatids do not align in metaphase II.
|
|
|
Homologous chromosomes do not separate in anaphase II.
|
Detailed explanation-1: -Mitotic nondisjunction can occur due to the inactivation of either topoisomerase II, condensin, or separase. This will result in 2 aneuploid daughter cells, one with 47 chromosomes (2n+1) and the other with 45 chromosomes (2n-1). Nondisjunction in meiosis I occurs when the tetrads fail to separate during anaphase I.
Detailed explanation-2: -Nondisjunction can occur during meiosis I and meiosis II, resulting in abnormal chromosomes number of gametes. The key difference between nondisjunction in meiosis 1 and 2 is that during meiosis 1, homologous chromosomes fail to separate while in meiosis II sister chromatids fail to separate.
Detailed explanation-3: -Nondisjunction is the failure of homologous chromosomes to disjoin correctly during meiosis. This results in the production of gametes containing a greater or lesser chromosomal amount than normal ones. Consequently the individual may develop a trisomal or monosomal syndrome.