Exam 8: Chromosomes and Human Genetics

As shown in the figure below,the number of males born each year with hemophilia ________ the number of males born with Fragile-X syndrome each year.

A person is genetically XX and develops as a male.How can this be explained?

Researchers hope to develop treatments for sex-linked genetic disorders such as Wiskott-Aldrich syndrome (WAS),by using a virus to insert a properly functioning gene into the patient's blood cells.This technique for correcting defective genes is ________,a specific type of genetic engineering.

An individual who has the genotype XᴺXⁿ for night blindness is considered a ________ for night blindness.

Ross is a genetic counselor working with a family that has lost a child to an unidentified illness.The family tells him there have been other children in the family history who have died after having the same symptoms.As Ross examines several generations of the family's pedigree,he notices that females are affected as frequently as males and that parents never exhibit the symptoms.This information leads him to think this disorder has a(n)________ mode of inheritance.

Can a male human be a carrier of an X-linked trait? Explain your answer.

A karyotype from an adult male indicates a chromosomal abnormality,which does not affect his health.Which of the following abnormalities is MOST likely seen?

If the male in generation II of the figure below was affected,what would the pattern of inheritance MOST likely be?

Which of the following statements would indicate a pedigree that shows the inheritance pattern of a recessive X-linked disease?

What characteristics of inheritance would allow you to distinguish whether a disorder is recessive autosomal,dominant autosomal,or sex-linked?

Would a karyotype for a human male be considered normal if it shows 45 autosomes and a single pair of sex chromosomes? Explain your reasoning.

If a genetic disorder is caused by a dominant allele,individuals with which of the following genotypes would be affected by the disorder?

A horizontal line directly between a square and a circle in a pedigree indicates that those two individuals are a(n)________ pair.

In which of the following situations would looking at a pedigree be MOST useful?

Explain how an individual who has both an X and a Y sex chromosome would develop embryologically as a female instead of a male.

The source of the gene needed for gene therapy treatment of the sex-linked adrenoleukodystrophy (ALD)would be a(n)________ chromosome with a ________ copy of the ALD gene.

Most inherited human disorders are the result of

An allele that is not expressed in heterozygous carriers is called a(n)________ allele.

What factors make it difficult to study human genetic disorders?

A female who is a carrier of the sex-linked gene A has the genotype