Because of non-disjunction in some stocks of Drosophila. melanogaster, about 1 in 65,000 egg cells have two copies of the X chromosome and about 1 in 375 egg cells have no X chromosome. Assuming that meiosis in males is always normal', what is the expected frequency of XXX females and XO males arising from any number of fertilized eggs? Do not be concerned as to whether it is lethal or not.

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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.

During metaphase I of meiosis, tetrads align along the metaphase plate independently of each other. Therefore, there is a random “shuffle” of maternal and paternal chromosomes in the resulting gametes.The following diagram demonstrates how this works in a diploid cell with four chromosomes . Because there are two pairs of chromosomes and each pair can align in one of two ways during metaphase I, the number of possible variations in the gametes produced is , or .For an organism that is , there are three pairs of chromosomes, so the number of possible variations in the gametes produced due to independent assortment in metaphase I is , or . In an organism with a haploid number of , how many possible combinations of maternal and paternal chromosomes can occur in its gametes? Select one: a. 72=49 b. 27=128 c.17=1 d. 214=16 384

. A mature female wolf, with 78 diploid chromosomes in each somatic cell, produces haploid oocytes (egg cells) containing how many chromosomes per cell? 1 sex-determining chromosome (Y) and 38 autosomes 2 sex-determining chromosomes (XX) and 76 autosomes 1 sex-determining chromosome (X) and 39 autosomes 2 sex-determining chromosomes (XY) and 76 autosomes 1 sex-determining chromosome (X) and 38 autosomes

GENETICS In a sexually reproducing diploid organism in which 2n=6, a normal meiocyte in reduction should exhibit a total of 3 bivalents at the metaphase plate. Consider the following organism in the previous statement. if there is no crossing over, the number of possible haploids (gamete) genotypes generated by "chromosome shuffling" during meiosis is _____?

The Oregon creeping vole, Microtus oregoni, has a very unusual meiosis?. In this rodent, males are XY, while females are XØ (that is, females have only a single X chromosome). During female meiosis, eggs that receive no maternal X chromosome do not mature, so females only produce eggs with exactly one X chromosome. As chromosome content is unchanged from generation to generation, M. oregoni males (who are XY) must deliberately nondisjoin their sex chromosomes. 1a) What types of sperm would M. oregoni have to produce (considering only their sex chromosome content) so that progeny get the right chromosomes? Remember, no inviable combinations are normally produced. 1b) Draw a Punnett square for the sex chromosomes in a M. oregoni mating, with the gametes that are actually produced. Indicate the sex of each offspring. 1c) From which parent do M. oregoni get their X chromosomes? Circle one. Mom Only Random Mom or Dad Dad Only

based on fig 1. Is this karyotype a male or female? Is there a chromosomal disorder? What type of chromosomal disorder?

A diploid (2n) trihybrid individual with the genotype EeFfGg can make eight genetically different gametes.  Loci E/e and F/f are on chromosome 1 and locus G/g is on chromosome 2. Explain how a gamete containing the alleles e, f and g may be produced by meiosis. Refer specifically to meiotic events occurring during Prophase I, Metaphase I, Anaphase I and Anaphase II. (NB: remember to refer to the organism above).