Exam 2: Single-Gene Inheritance

Yellow leaves on a plant can be caused by genetic mutations,viruses,or unfavorable environmental conditions.Suppose you find a plant that has yellow leaves,and you want to determine if the cause of the phenotype is a genetic mutation or an environmental stress.Design an experiment to differentiate between the different possibilities.

Mice (Mus musculus)have 40 chromosomes per diploid cell (2n = 40).How many double- stranded DNA molecules and how many chromosomes are there in a mouse cell that is in the G2 stage of the cell cycle?

A female rabbit of phenotype c′ is crossed to a male rabbit with c^ch.The F₁ is comprised of five rabbits with a c′ phenotype,two with c^ch phenotype,and three with c phenotype.Of the phenotypically c rabbits,two are females and are backcrossed to their father.This cross produces only rabbits with c^ch phenotype.These results suggest that:

"Dumpy" is a commonly used mutant phenotype in the nematode worm C.elegans.Two "Dumpy" individuals are crossed to each other,and this cross produces 210 "Dumpy" and 68 wild-type individuals.If one of the "Dumpy" individuals used in this cross was mated with a wild type,what "Dumpy": wild-type ratio would we observe in the offspring?

You have three jars of gumballs.The first jar has 100 white gumballs and 25 green,the second jar has 50 white and 150 blue,and the third jar contains 500 white and 10 red. If you randomly draw one gumball from each jar,what is the probability for $\textbf{ all white OR all colored gumballs? }$

What is the probability that individual A is a heterozygous with respect to the condition depicted in the pedigree?

You have three jars of gumballs.The first jar has 100 white gumballs and 25 green,the second jar has 50 white and 150 blue,and the third jar contains 500 white and 10 red. If you randomly draw one gumball from each jar,what is the probability for $\textbf{ at least one white gumball? }$

In a particular species of plants,flower color is dimorphic: some individuals have red flowers,whereas others have yellow flowers.If flower color is controlled by a single gene with two alleles (c^red and c^yellow): a)what would be the simplest way to determine which allele is dominant? b)what will be the genotypic ratio in the offspring of a cross between a monohybrid and a pure-breeding individual?

A very common type of red-green colorblindness in humans is caused by a mutation in a gene located on the X chromosome.Knowing that the mutant allele is recessive to the wild type,what is the probability that the son of a woman whose father is colorblind is going to also be colorblind?

The following pedigree depicts the inheritance of a rare hereditary disease affecting muscles. What is the most likely mode of inheritance of this disease?

A young woman is worried about having a child because her mother's only sister had a son with Duchenne muscular dystrophy (DMD).The young woman has no brothers or sisters.(DMD is a rare X-linked recessive disorder.) a)Draw the relevant parts of the pedigree of the family described above.(Be sure to include the grandmother,the three women mentioned,and all their mates.) b)State the most likely genotype of everyone in the pedigree. c)Calculate the probability that the young woman's first child will have DMD.