BIOL 4003 Chapter Notes - Chapter 2: Punnett Square

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30 Aug 2018

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Several varieties which produced various heights appearance of flowers, seeds, and pods. Mendel called them unit factors , we call them genes: always saw a 3:1 ratio of dominant: recessive, led him to suggest that genes segregate. The two copies of a gene segregate from each other during transmission from parent to offspring. Mendel"s two-factor cross procedure: cross 2 true-breeding strains f1 gen (rryy + rryy rryy, collect seeds and record phenotype, f1 self-fertilize f2 generation, analyze characteristics. ***this experiment led to mendel"s law of independent assortment: Different genes will randomly assort their alleles during the formation of haploid cells. Need to check in lecture/office hours: loss-of-function alleles: defective genes. Can indicate function of gene (ex: make a protein that causes purple pigment/enzyme that makes pigment, so the loss-of-function allele would result in a flower w/o pigment) Use pedigrees to analyze whether traits are dominant or recessive. When more than 2 available outcomes, use multinomial expansion equation:

Related Questions

A professor asks you to help perform a Mendel-type pea plant experiment. She wants to see how independent some of the traits that Mendel inspected really are. To get started, she tells you she did a test cross and shows you a greenhouse full of F1 pea plants. She asks you to continue her experiment while she has to attend a scientific meeting in Europe, and to cross the F1's to generate F2 offspring. You do this with the help of the professors graduate students and get 3044 plants (wow, you guys did a lot of work!). Mendel looked at seven pea plant traits (https://en.wikipedia.org/wiki/Gregor_Mendel): seed shape, flower color, seed coat tint, pod shape, unripe pod color, flower location, and plant height. If Mendelian inheritance were true, how many plants would you roughly expect to be phenotypically recessive in seed shape, pod shape and plant height, but genetically heterozygous in the other traits? Enter an integer number (round up).

1.
In wolves, black coat color is recessive to the normal grey, andblue eye color is recessive to brown. A black-coated blue eyed malemates with a female who is heterozygous for both traits, and thereare 8 pups in the litter.
What are the expected genotoypes of the pups? what are the expectedphenotypes?

2.
A man and a woman both have normal color vision, and both havecolorblind fathers.
What proportion of their daughters would you expect to be colorblind?
What proportion of their sons?

3.
Assume that in the U.S. in 1960, the frequency of the autosomalrecessive Tay-Sachs disease among eastern European Jews was 1 per3600births.
What was the frequency of the Tay-Sachs allel in thispopulation?
In 1961, a woman of polish ancestry whose brother died of Tay-Sachsdisease marries a Jewish man of Hungarian ancestry. Assuming thatshe is a carrier, what is the probability that their first childwill have Tay-Sachs disease?

4. In fruit flies, black body (b) is recessive to normal body color(B). In a breeding study, a population of flies is allowed to mateat random. In the population, 3000 flies are homozygous for blackbody color, and 2000 flies are homozygous for the normalallele.
What is the frequency of each genotype in the F1 generation?
What would the proportion of phenotpyes be?
What is the frequency of the two alleles, B and b, in the F1generation?

5.
In peas, the dominant seed shape is round and the recessive iswrinkled(w). The dominant trait for pod color is green andrecessive is yellow (y). A plant with round seeds and green podsthat i heterozygous only for the color trait is crossed with aplant that has wrinkled seeds and yellow pods, and the resulting F1progeny are selfed(self fertilized).
Write out the P1 genotpes and the F1 and F2 genotypic andphenotypic ratios.
What proportion of the plants with green pods and round seeds fromthe F2 generation would you expect to be true breeding(i.e. produceonly plants with green pods and round seeds)?

Thank you

BIOL 4003 Chapter Notes - Chapter 2: Punnett Square

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