Question

PLEASE READ THE INSTRUCTIONS CAREFULLY. YOU WILL NOT RECEIVE POINTS IF YOU DO NOT ANSWER THE QUESTION THAT IS ASKED! The following questions apply to the cell below: An ZA bagb biggb you 19 pts] Draw this cell going through meiosis, showing the outcomes of meiosis and meiosis II- but experiencing NONDISJUNCTION of the B chromosomes in MEIOSIS II. Label each gamete as diploid, haploid, n+1 or n-1. You do NOT need to show crossover. You do NOT need to show fertilization.

Answer 1

METAPHASE-1 ANAPHASE-1 A А А X А А B n 6 8 Sn

METAPHASE-2 ANA PHASE - 2 n E E b ) d 3,4 A A ད+| B B བ བ བ ་ 8 8 R-1

Nondisjunction occurs when the sister chromatids fail to separate during Anaphase 2 of meiosis2. Nondisjunction can also occur between homologous chromosomes which fail to separate during Anaphase 1 of meiosis 1. Here, meiosis1 is normal, which starts with a diploid cell that gives two haploid cells at the end of meiosis1. Meiosis 2 begins with two haploid cells, where there's a nondisjunction of B chromosome and results in the formation of four haploid cells out of which two gametes are normal and one gamete has n+1 chromosomes and the other gamete has n-1 chromosome due to nondisjunction.