Genetics and Inheritance

My subtle coloring did not come out well in this scan-imagine light tan skin!

Genetics Problems:                         1.       For each of the diploid genotypes presented below, determine the genetic make up for all of the possible gametes that would result through the process of meiosis. Remember, each egg or sperm must have one of each letter. That letter can be upper or lower case. a.       Rr  R or r b.      RrYy   RY, Ry, ry, c.       rrYy   rY, ry d.      RrYY  RY, rY 2.       For each of the following, state whether the genotype of a diploid or haploid cell is represented. a.       D Haploid b.      GG Diploid c.       P Haploid d.      ee Diploid 3.       Yellow guinea pigs crossed with white ones always produce cream colored offspring. Two cream colored guinea pigs when crossed produced yellow, cream and white offspring in the ratio of l yellow: 2 cream: l white. Explain how are these colors inherited?  No calculations needed! Name the type of inheritance this represents.        This represents incomplete dominance, where the heterozygous type is expressed as an intermediate phenotype. Because the cream colored guinea pigs are heterozygous, they contain one allele each of the yellow or white gene, and when mated with each other, can produce either white, yellow, or cream offspring, depending on which alleles each parent gives. 4.       In sheep white is due to a dominant gene (B), black to its recessive allele (b). A white ewe mated to a white ram produces a black lamb. What are the genotypes of the parents? You might need to construct Punnet squares experimenting with different crosses to come up with this answer. Name the type of inheritance this represents.               B                           b                                                      Allele(s) from Mother Allele(s) from Father Genotype Phenotype Sex of child:  X X XX female Face shape r r rr square Chin Shape (I) v V Vv very prominent Chin Shape (II) R r Rr round Cleft chin a a aa present Skin color abCd abcD aabbCcDd very light brown Hair type c C Cc wavy Widow’s Peak w W Ww present Eyebrows (I) b B Bb bushy Eyebrows (II) N N NN not connected Eyebrow color H H HH darker than hair Eyes distance apart E e Ee average distance Eyes size e E Ee medium Eyes shape A a Aa almond Eyes slant H h Hh horizontal Eyelashes l l ll short Eye color ABC aBc AaBBCc light brown Mouth size M M MM wide Lips L L LL thick Protruding lower lip H h Hh slightly protruding Dimples d d dd absent Nose size N n Nn average Nose shape R r Rr rounded Nostril shape R r Rr rounded Earlobe Attachment F F FF free Freckles on checks f f ff absent Hair color ABCD abCd aabbCcDd brown           BB Bb Bb bb                 B                                                                              b                                                The parents would both have to be Bb heterozygous. This is homozygous recessive inheritance.           G                      g g Gg gg g Gg gg 5.       In peas, yellow color (G) is dominant to green color (g). A heterozygous yellow is crossed with a green. What is the expected phenotype ratio of the offspring? Name the type of inheritance this represents.                                                                         There is a 50/50 ratio of green to yellow. This confers both heterozygous and homozygous recessive inheritance. 6.       White color (Y) is dominant to yellow color (y) in squash. A heterozygous white fruit plant is crossed with a yellow fruit plant. What is the expected phenotype ratio of the offspring? What is this type of inheritance called? Y y y Yy yy y Yy yy There is a 50/50 ratio of white to yellow squash. This is heterozygous and homozygous recessive inheritance. 7.       In certain flowers, a cross between homozygous red and a homozygous white will always result in a pink flower. A cross is made between two pink flowers. What is the predicted phenotype ratio of the colors red, pink and white appearing in the offspring? What is this type of inheritance called    R W R RR RW W RW WW There will be a 25% chance for white or red, and 50% chance of pink.  This is an example of incomplete dominance due to heterozygous genotypes. 8.       In humans, the condition for normal blood clotting dominates the condition for non-clotting or hemophilia. Both alleles are linked to the X chromosome. A male hemophiliac marries a woman who is a carrier for this condition. In this respect, a carrier is a woman who has an allele for normal blood clotting and an allele for hemophilia. What are the chances that if they have a male child he will be normal for blood clotting? What is this type of inheritance called? XH Xh Xh XHXh XhXh Y XHY XhY There is a 50% chance that a son will be normal for blood-clotting.  This is sex-linked inheritance. 9.       A person with an allele for type A blood and type O blood marries someone with an allele for type B blood and type O blood. List the types of offspring they could have and the probability for each blood type in the offspring. (A allele = IA, B allele = IB, O allele = i) What is the expected phenotype ratio of the offspring? What is this type of inheritance called? IA i IB IAIB IBi i IAi ii There is a 25% chance that the blood type will be AB, a 25% chance that it will be O, a 25% chance that it will be A, and a 25% chance that it will be B. This is called codominance. 10.   Skin color in humans becomes darker by the number of dominant alleles; AABBCC have the darkest skin and aabbcc have the lightest skin. Place these genotypes in sequence according to the color of skin expected for each. Place the darkest skin first. What is this type of inheritance called? Genotypes: AaBbCc, AAbbcc, aabbCc, AaBBCc, AaBBCC. AaBBCC, AaBBCc,AaBbCc,AAbbcc,aabbCc This is called polygenic inheritance.