Exam 4: Extensions of Mendelian Genetics

In the mouse,gene A allows pigmentation to be deposited in the individual coat hairs; its allele a prevents such deposition of pigment,resulting in an albino.Gene B gives agouti wild- type fur ; its allele b gives black fur.What would the expected ratio of the progeny be in a cross of a doubly heterozygous agouti mouse mated with a doubly homozygous recessive white mouse?

Name three modes of inheritance that are influenced by the sex of individuals.

The white- eyed gene in Drosophila is recessive and sex- linked.Assume that a white- eyed female is mated to a wild- type male.What would be the phenotypes of the offspring?

Multiple mutations that are found to be present in a single gene are said to belong to the same ________ group.

If an X- linked disorder is lethal to the affected individual prior to the age at which one reaches reproductive maturation,the lethality will be expressed only in males.Why is this so?

Assume that a dihybrid F₂ ratio,resulting from epistasis,was 9:3:4.If a double heterozygote was crossed with the fully recessive type,what phenotypic ratio is expected among the offspring?

An allele of RNA polymerase in Drosophila demonstrates a recessive lethal inheritance pattern.Which of the following is true?

The accompanying figure is a pedigree of a fairly common human hereditary trait in which the boxes represent males and the circles represent females.Shading symbolizes the abnormal phenotype. Given that one gene pair is involved,what is the inheritance pattern?

Which of the following statements is true?

Which of the following statements is false?

Which of the following statements is true?

Typically,when one wishes to represent a gene,the symbol used is ________.

With incomplete dominance,a likely ratio resulting from a monohybrid cross would be ________ .

What is a significant difference between X- linked and sex- influenced inheritances?

What is the term for a gene mutation that leads to a myriad of disparate effects?

Comb shape in chickens represents one of the classic examples of gene interaction.Two gene pairs interact to influence the shape of the comb.The genes for rose comb R and pea comb P together produce walnut comb.The fully homozygous recessive condition rrppproduces the single comb.Assume that a rose- comb chicken is crossed with a walnut- comb chicken and the following offspring are produced: 17 walnut,16 rose,7 pea,and 6 single.What are the probable genotypes of the parents?

A situation in which there are more than two alternative forms of a given gene would be called ________ .

The deficiency of the enzyme glucose- 6- phosphate dehydrogenase G6PD is inherited as a recessive gene on the X chromosome in humans.A phenotypically normal woman whose father had G6PD is married to a normal man.What fraction of their sons would be expected to have G6PD?

What is the most prevalent form of an allele called?

A ________ is one whose expression is influenced by some environmental condition.