FIGURE 2-8 Simplified representation of mitosis and meiosis in diploid cells (2n, diploid; n, haploid). (Detailed versions are shown in Appendix 2-1, page 83.) Mitosis Interphase Prophase Metaphase 2n 4n Replication Meiosis Interphase Prophase I Metaphase I 2n 4n Replication Pairing make up a bivalent are called a tetrad (Greek for “four"), to indicate that there are four homologous units in the bundle. - dyad: bivalent< SC tetrad `dyad: !!

An individual that is heterozygous for an inversion has the following chromosomes(∗ is the centromere):M N O  P  Q  • R  S  T  Um  n  o t   s  r  • q  p  u  Assume that a crossover occurred between P and Q.  Starting with “M” allele, list the remaining genes in order (NO spaces between the letters) of the chromosome resulting from crossing over. You must use upper and lower-case letters correctly and the * symbol for the centromere(s).

What will be the number of chromosomes in Turner’s syndrome and Klinefelter's syndrome of an organism whose haploid number is 20

In fruit flies, chromosomal crossing over does not occur in meiosis in males, whereas crossing over does occur in meiosis in females. In fruit flies that are heterozygous at many genes (i.e. many maternal and paternal versions of the genes differ), at what stage would cells no longer be heterozygous for any gene during the process of meiosis? a)After the second meiotic division in males, and after the first meiotic division in females. b)After the second meiotic division in both males and females. c)After the first meiotic division in both males and females. d)After the first meiotic division in males, and after the second meiotic division in females.

How do you determine the amount of DNA picograms for each stage in Meiosis? (for a cell 2n=4 for reference)

Assume that the diploid number of a certain species is four chromosomes, two large and two small (2n=4). a)  Of the following figures, which represents a 3n (triploid) cell in mitotic metaphase? b)  For each of the wrong answers from part (a) above, explain briefly why it cannot represent a triploid cell in mitotic metaphase.