Exam 13: Extensions of and Deviations From Mendelian Genetic Principles

The distinctive fur pattern of Siamese cats results when genes that are responsible for the coat color are influenced by

Explain and differentiate among the molecular bases of codominance,incomplete dominance,and complete dominance.

In a genotype with complete penetrance,less than 100% of individuals with a particular genotype exhibit the expected phenotype.

Dextral (D) and sinistral (d) shell coiling in the water snail Limnaea peregra is genetically determined. From a population of mixed sinistral and dextral snails, a sinistral female and a dextral male are chosen. All the offspring are dextral. When the female offspring are mated, 50% produce only sinistral snails and the other 50% produce only dextral snails. -What were the genotypes of the sinistral female and dextral male that were initially chosen?

Generally,blue eyes are recessive to dark brown eyes in humans.Individuals with albinism typically have blue eyes with a strong red reflection.A blue-eyed woman with albinism marries a man who is blue-eyed but does not have albinism.All their children have dark brown eyes.How can this be explained?

Manx cats have no tails.When two Manx cats are bred together there is always a one third chance that a kitten will have a tail.When a Manx cat is bred to a cat with a normal tail there is a one-half chance that a kitten will have a tail.Which of the following is the best explanation for this?

What is the cause of Tay-Sachs disease?

For a gene with multiple alleles,what is the maximum number of alleles that a diploid organism may have?

In a dihybrid cross with independent assortment of the two genes,any deviation from the Mendelian 9:3:3:1 ratio indicates that the phenotype is the product of the interaction of two or more genes.

An allele that exhibits incomplete dominance is usually haplosufficient.

In the ABO blood-type system,which genotypes could confer type A blood to a person?

A person with type B blood could safely receive a transfusion of blood from someone with blood type

Two persons who have recessive genetic deafness marry and have 6 children.All the children can hear.The reason they can hear is most likely due to

How could a man with blood type A and a woman with blood type B produce a child with blood type O?

Sex-limited traits are caused by genes that are on sex chromosomes.

In cats,the dominant white gene (W)may or may not also cause deafness.Homozygotes are more likely to be deaf than heterozygotes.If you breed heterozygous white cats together and produce 100 kittens,how many would you expect to be deaf if all the proportions came out perfectly? Assume that heterozygotes have an 8% chance of being deaf,and homozygotes a 60% chance of being deaf.

Comb shape in chickens also involves the interaction of two genes,but the F₂ generation shows a typical 9:3:3:1 Mendelian ratio.How does this work?

People affected by diseases caused by mtDNA defects

Studies performed on identical twins separated at birth have shown that many phenotypes,such as IQ or alcoholism,are influenced by the person's genotype as well as by their environment.

Phenylketonuria (PKU)is an example of a phenotype that is solely influenced by genes.