Exam 2: Extensions to Mendels Laws

When do human oocytes normally complete meiosis I?

Colour vision depends upon the dominant alleles of three genes: the R gene and the G gene are both on the X chromosome,while the B gene is autosomal.Recessive mutations in any of the three genes can cause colour blindness.Suppose a colour-blind man marries a colour-blind woman and all of their offspring have normal vision.What is the genotype of the woman?

Which aspect(s)of chromosome behaviour is/are primarily responsible for the tremendous amount of genetic variability associated with sexual reproduction?

The chromosomal structure to which spindle fibers attach during the mitotic divisions is referred to as a

Individuals with an XXY karyotype are ______ in humans and ______ in fruit flies.

Suppose you discover a new species of worm that exists in two forms-slimy and non-slimy.You find that mating slimy females with non-slimy males produces offspring consisting of slimy males and non-slimy females,whereas mating non-slimy females with slimy males produces offspring of both sexes that are all slimy.You would conclude that the _________ allele is dominant and that ________ are the heterogametic sex (the sex with two different sex chromosomes)in this species of worm.

In crosses of white-eyed Drosophila females with red-eyed males,Bridges recovered white-eyed daughters and red-eyed sons at a rate of around one per 2,000 offspring.(Most of the offspring were white-eyed males and red-eyed females. )He hypothesized that these exceptional progeny resulted from nondisjunction of the X chromosomes in meiosis in the female.What is the expected karyotype of the exceptional red-eyed males? Give two ways to test this predicted karyotype.

A cell with three pairs of chromosomes has the genotype AaBbCc,such that each pair of alleles is on a different pair of chromosomes.If this cell were to undergo meiotic division,how many genetically different types of gametes could be produced?

The following is a list of mitotic events in no particular order. A: Chromosomes align on the midplate of the cell. B: Kinetochores begin attaching to spindle fibers. C: Nuclear membrane reforms and chromosomes decondense. D: Chromosomes condense and centrosomes migrate to opposite sides of nucleus. E: Sister chromatids separate and move to opposite poles. What is the correct order of events?

In the following pedigree,the indicated trait is caused by which type of allele? Assume the trait is fully penetrant and that the trait is rare in the population,so that alleles for the trait are not carried by anyone who is not the progeny of a mating shown in the pedigree.

Cells in the G₂ stage of the cell cycle have ______ as cells of the same species in the G₁ stage.

Microtubules that attach to centrosomes but not chromosomes and that interdigitate with microtubules emanating from the centrosome at the opposite pole are known as

In the following pedigree,the indicated trait is caused by which type of allele? Assume the trait is fully penetrant.

Males with one copy of an X-linked gene are said to be _________ for that gene.

Nondisjunction can occur at either the first or second division of meiosis.XYY individuals would most likely arise from nondisjunction at the ______ meiotic division in the _____.

What are the consequences of a mutation that disrupts cytokinesis for cells that are actively dividing?

Red-green colour blindness is controlled by an X chromosome gene in humans.A normal man and normal woman whose fathers are both colour-blind marry.What is the probability that their first child will be colour-blind?

Which of the following events occurs during mitosis but not during meiosis?

What aspect of chromosome behaviour most clearly accounts for Mendel's law of segregation?

Suppose you discover a new variant in which mice have spiky fur instead of the usual soft fur.You notice that this trait seems only to be present in males.To investigate this pattern,you cross a spiky-fur male with a soft-fur female,and find that all of the F₁ progeny of both sexes have soft fur.You then interbreed the F₁ and observe that all of the F₂ females have soft fur,but 1/4 of the F₂ males have spiky fur.You conclude that the spiky allele is