Exam 15: The Chromosomal Basis of Inheritance

Abnormal chromosomes are frequently found in malignant tumours.Errors such as translocations may place a gene in close proximity to different control regions.Which of the following might then occur to make the cancer worse?

In humans,clear gender differentiation occurs,not at fertilization,but after the second month of gestation.What is the first event of this differentiation?

What is a syndrome?

Duchenne muscular dystrophy (DMD)is caused by a gene on the human X chromosome.The patients have muscles that weaken over time because they have absent or decreased dystrophin,a muscle protein.They rarely live past their 20s.How likely is it for a woman to have this condition?

Suppose that a gene on human chromosome 18 can be imprinted in a given pattern in a female parent but not in a male parent.A couple in whom each maternal meiosis is followed by imprinting of this gene have children.What can we expect as a likely outcome?

Down syndrome has a frequency in the Canadian population of ~4/10,000 live births.In which of the following groups would you expect this frequency to be significantly higher?

A gene is considered to be non-Mendelian in its inheritance pattern if it seems to "violate" Mendel's laws.Which of the following would be considered Mendelian?

Correns described that the inheritance of variegated colour on the leaves of certain plants was determined by the maternal parent only.What phenomenon does this describe?

Use the following information to answer the questions below. The following is a map of four genes on a chromosome. -Between which two genes would you expect the highest frequency of recombination?

An abnormal number of a specific chromosome is referred to as

Leber's hereditary optic neuropathy does not follow Mendelian genetic because it is

The phenotype most commonly observed in a natural population is the

If genomic imprinting depends on the sex of the parent who transmits the gene,which of the following must be true?

A couple has a child with Down syndrome.The mother is 39 years old at the time of delivery.Which of the following is the most probable cause of the child's condition?

SRY is best described in which of the following ways?

Recombination between linked genes comes about for what reason?

Sex determination in mammals is due to the SRY region of the Y chromosome.An abnormality of this region could allow which of the following to have a male phenotype?

What is the reason that linked genes are inherited together?

Refer to the following information to answer the questions below. A man who is an achondroplastic dwarf with normal vision marries a colour-blind woman of normal height.The man's father was 6 feet tall,and both the woman's parents were of average height.Achondroplastic dwarfism is autosomal dominant,and red-green colour blindness is X-linked recessive. -How many of their daughters might be expected to be colour-blind dwarfs?

How would one explain a testcross involving F₁ dihybrid flies in which more parental-type offspring than recombinant-type offspring are produced?