Exam 4: Extensions of Mendelian Genetics

The following coat colors are known to be determined by alleles at one locus in horses: palomino = golden coat with lighter mane and tail cremello = almost white chestnut = brown The following table gives ratios obtained in matings of the above varieties: Cross Parents Offspring 1 cremello \times cremello all cremello 2 chestnut \times chestnut all chestnut 3 cremello \times chestnut all palomino 4 palomino \times palomino 1/4= chestnut 1/2= palomino a) Assign gene symbols for the genetic control of coat color on the basis of these data. b) Diagram the last two matings.

Can females display pattern baldness?

The trait of medium-sized leaves in iris is determined by the genetic condition PP'.Plants with large leaves are PP,whereas plants with small leaves are P'P'.A cross is made between two plants each with medium-sized leaves.If they produce 80 seedlings,what would be the expected phenotypes,and in what numbers would they be expected? What is the term for this allelic relationship?

A conditional mutant is one whose expression is influenced by some environmental condition.

A particular cross gives a modified dihybrid ratio of 9:7.What phenotypic ratio would you expect in a testcross of the fully heterozygous F₁ crossed with the fully recessive type? Diagram the testcross using A,a,B,b as symbol sets.

Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white,aaBB or aaBb gives yellow,and aabb produces green.Assume that two fully heterozygous plants are crossed.Give the phenotypes (with frequencies)of the offspring.