Exam 7: Sex Determination and Sex Chromosomes

The accompanying figure is a pedigree of a fairly common human hereditary trait; the boxes represent males and the circles represent females.Filled in symbols indicate the abnormal phenotype.Given that one gene pair is involved, a) Is the inheritance pattern X-linked or autosomal? b) Give the genotype of each individual in the pedigree.If more than one genotypic possibility exists,present all possible alternatives.

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

The Protenor mode of sex determination is the ________.

What particular karyotype was at one time considered to be related to criminal predisposition?

Normally in humans,all the sons of a female homozygous for a sex-linked recessive gene will inherit that trait.

Describe three distinct genetic regions of the human Y chromosome.

An individual with Klinefelter syndrome generally has one Barr body.

Give the sex of the following organisms assuming that the autosomes are present in the normal number. Sex Chromosome Organism Complement Humans Drosophila XX XY XO XXX XXY

An individual with Turner Syndrome has no Barr bodies.

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.

Individuals have been identified who have two different karyotypes,such as 45,X/46,XY or 45,X/46,XX.Such individuals are called ________.

List three abnormalities involving numbers of X chromosomes.

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

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.

Studies done in the 1960s suggested that individuals with the XYY condition were prone to criminal behavior.What conclusions presently seem appropriate concerning this chromosomal condition?

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.

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

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

A cross is made between a female calico cat and a male cat having the gene for black fur on his X chromosome.What fraction of the offspring would one expect to be calico?

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 ________.