Exam 15: The Chromosomal Basis of Inheritance

A phenotypically normal prospective couple seeks genetic counselling because the man knows that he has a translocation of a portion of his chromosome 4 that has been exchanged with a portion of his chromosome 12.Although he is normal because his translocation is balanced,he and his wife want to know the probability that his sperm will be abnormal.What is your prognosis regarding his sperm?

Cinnabar eyes is a sex-linked recessive characteristic in fruit flies.If a female having cinnabar eyes is crossed with a wild-type male,what percentage of the F₁ males will have cinnabar eyes?

A nonreciprocal crossover causes which of the following products?

A homozygous tomato plant with red fruit and yellow flowers was crossed with a homozygous tomato plant with golden fruit and white flowers.The F₁ all had red fruit and yellow flowers.The F₁ were testcrossed by crossing them to homozygous recessive individuals and the following offspring were obtained: Red fruit and yellow flowers-41 Red fruit and white flowers-7 Golden fruit and yellow flowers-8 Golden fruit and white flowers-44 How many map units separate these genes?

The term hemizygous refers to

-The pedigree in the figure above shows the transmission of a trait in a particular family.Based on this pattern of transmission,the trait is most likely

-What is an adaptive advantage of recombination between linked genes?

Of the following human aneuploidies,which is the one that generally has the most severe impact on the health of the individual?

Which of the following is known as a Philadelphia chromosome?

What is the greatest benefit of having used a testcross for this experiment?

-What is the definition of one map unit?

Red-green colour blindness is a sex-linked recessive trait in humans.Two people with normal colour vision have a colour-blind son.What are the genotypes of the parents?

Which of the following is true of aneuploidies in general?

-In a series of mapping experiments,the recombination frequencies for four different linked genes of Drosophila were determined as shown in the above figure.What is the order of these genes on a chromosome map?

Glucose-6-phosphate dehydrogenase deficiency (G6PD)is inherited as a recessive allele of an X-linked 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 was not normal but was G6PD deficient,would you change your answer in part (a)?

In cats,black fur colour is caused by an X-linked allele; the other allele at this locus causes orange colour.The heterozygote is tortoiseshell.What kinds of offspring would you expect from the cross of a black female and an orange male?

Which of the following produces a Mendelian pattern of inheritance?

Pseudohypertrophic muscular dystrophy is a human disorder that causes gradual deterioration of the muscles.Only boys are affected,and they are always born to phenotypically normal parents.Due to the severity of the disease,the boys die in their teens.What can we deduce about the disorder?

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. -What proportion of their sons would be colour-blind and of normal height?

Which of the following is the meaning of the chromosome theory of inheritance as expressed in the early 20th century?