Exam 7: Sex Determination and Sex Chromosomes

Although triple-X human females typically have normal offspring, what kinds of gametes, with respect to the X chromosomes, would you expect from such XXX females? Draw meiotic stages that show the gametes that are expected to be produced.

One form of hemophilia is caused by a sex-linked recessive gene. Assume that a man with hemophilia marries a phenotypically normal woman whose father had hemophilia. What is the probability that they will have a daughter with hemophilia? (Note: In this problem, you must include the probability of having a daughter in your computation of the final probability.)

An individual with Klinefelter syndrome generally has one Barr body.

Data produced by C. Bridges in the early part of this century indicate that sex in Drosophila is determined by ________.

The sex of birds, some insects, and other organisms is determined by a ZW chromosomal arrangement in which the males have like sex chromosomes (ZZ) and females are ZW (similar to XY in humans). Assume that a recessive lethal allele on the Z chromosome causes death of an embryo in birds. What sex ratio would result in the offspring if a cross were made between a male heterozygous for the lethal allele and a normal female?

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is inherited as an X-linked recessive gene in humans. A woman whose father suffered from G6PD marries a normal man. a) What proportion of their sons is expected to be G6PD? b) If the husband were not normal, but were G6PD deficient, would you change your answer in part (a)?

In Drosophila, the female is the heterogametic sex.

Assume that a man who carries an X-linked gene has children. Assuming normal meiosis and random combination of gametes, the man would pass this gene to ________.

The Lygaeus mode of sex determination is the ________.

An individual with Turner Syndrome has no Barr bodies.

Give the sex-chromosome constitution (X and Y chromosomes) and possible genotypes of offspring resulting from a cross between a white-eyed female (X^w X^wY) and a wild-type male (normal chromosome complement) in Drosophila melanogaster. Include all zygotic combinations whether viable or inviable.

In Drosophila, the sex of a fly with the karyotype XO:2A is ________.

Normally in humans, all the sons of a male showing a sex-linked phenotype will inherit the trait.

Assume that you are told that a particular organism, Drosophila, has the XO chromosome complement. You are also told that the autosomal complement is a normal 2n. You know that in humans the XO complement is female determining. Would you be correct in assuming that the Drosophila sex for XO is also female? Choose the answer that includes the correct explanation.

A color-blind woman with Turner syndrome (XO) has a father who is color blind. Given that the gene for the color-blind condition is recessive and X-linked, provide a likely explanation for the origin of the color-blind and cytogenetic conditions in the woman.

Klinefelter and Turner syndromes have how many chromosomes, respectively?

In Drosophila, an individual female fly was observed to be of the XXY chromosome complement (normal autosomal complement) and to have white eyes as contrasted with the normal red eye color of wild type. The female's father had red eyes, and the mother had white eyes. Knowing that white eyes are X-linked and recessive, present an explanation for the genetic and chromosomal constitution of the XXY, white-eyed individual. It is important that you state in which parent and at what stage the chromosomal event occurred that caused the genetic and cytogenetic abnormality.

In Drosophila, sex is determined by a balance between the number of haploid sets of autosomes and the number of ________.

Under what condition might a human female have the XY sex chromosome complement?

For an individual with the XXY chromosomal composition, the expected number of Barr bodies in interphase cells is ________.