Question

An unknown diploid organism has 14 chromosomes after mitosis.

a. How many chromatids does the organism have during the G2 phase of the cell cycle?
b. If non-disjunction occurs during Meiosis I for one of the chromosome pairs, how many chromosomes will be in any trisomic gametes?
c. If non-disjunction occurs during Meiosis I for one of the chromosome pairs, what percent of the resulting gametes will have below 7 total chromosomes?
d. If you observe a cell in metaphase, how can you visually observe whether the cell is in mitosis, meiosis, or meiosis II?

Answer 1

In a diploid organism having 14 chromosomes after mitosis, there would be 28 chromatids during the G2 phase. Trisomic gametes resulted from nondisjunction in Meiosis I would have 8 chromosomes, and no gametes would have less than 7 chromosomes.

Step-by-step explanation:

An unknown diploid organism with 14 chromosomes after mitosis would have 28 chromatids during the G2 phase of the cell cycle. Each chromosome consists of two sister chromatids at this stage. If nondisjunction occurs during Meiosis I for one of the chromosome pairs, trisomic gametes would contain 8 chromosomes, as one gamete would inherit an extra chromosome from the pair that did not segregate properly.

In the case of nondisjunction during Meiosis I, none of the resulting gametes would have below 7 total chromosomes because nondisjunction results in one gamete with an extra chromosome and one with one less; therefore, the minimum chromosome number in the gametes would be 6.