Question

A cell in the testes of a male bald eagle is getting ready to begin meiosis. The diploid number for this bird species is 66. How many replicated chromosomes are there in this testicular cell at metaphase I? How many sister chromatids are there in metaphase I? In each daughter cell, how many sister chromatids are there in prophase II? How many chromosomes are there in each sperm cell?

Answer 1

Answer:

Replicated chromosomes at metaphase I = 66

Sister chromatids at metaphase I = 66 x 2 = 132

Sister chromatids at prophase II = 66

Chromosomes in each sperm cells = 33

Explanation:

Metaphase I of meiosis I would have 66 replicated chromosomes in the testicular cells of the bird. Each of the replicated chromosomes would have two sister chromatids. So, a total of 66 replicated chromosomes would have 66 x 2 = 132 sister chromatids.  

Due to segregation of homologous chromosomes towards opposite poles in anaphase I, each daughter cell formed by the end of meiosis I would have 33 replicated chromosomes. So, each of the daughter cells would have a total 33 x 2 = 66 sister chromatids at prophase II.  

Since meiosis II maintains the chromosome number, each sperm cell formed by the end of meiosis II would have 33 chromosomes.