BICD100 FINAL KEY

BICD100 FINAL KEY - FINAL EXAM KEY BICD100 GENETICS Prof...

Info icon This preview shows pages 1–5. Sign up to view the full content.

View Full Document Right Arrow Icon
BICD100 GENETICS Prof. Chisholm FINAL EXAM KEY Thursday March 20, 2008 Class results: Distribution of total scores (both midterms + final) (excluding Ws) Total scores 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 0 5 10 15 20 25 Bin Center number of students Number of students completing class: 153 Mean score = 517 SD 153 (Distribution is normal) Maximum score = 849 Grades: > 673 = A > 517 = B > 361 = C > 206 = D FINAL EXAM KEY 1
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Question 1 The true-breeding “wild-type” strain of peas has yellow seeds. Fritz Mendel finds three independent true-breeding strains with green seeds (green 1,2 and 3). Fritz crosses each green-seeded strain to the true breeding yellow-seeded strain. From each cross he takes F 1 plants and allows them to self fertilize to yield the F 2 . Parental yellow x green 1 yellow x green 2 yellow x green 3 F 1 All yellow All yellow All green F 2 3:1 yellow:green 3:1 yellow:green 3:1 green:yellow (a) For each strain make up a symbol for the dominant and recessive alleles. State the symbols and the phenotype of each allele, making it clear which is dominant and which recessive. Use different symbols for the different strains. 5 points Uppercase alleles are dominant: Strain 1 G1 confers yellow g1 confers green Strain 2 G2 confers yellow g2 confers green Strain 3 g3 confers yellow G3 confers green (b) Using the symbols you defined in part (a), what are the genotypes of the green seeds in the F 2 of each strain? 5 points Cross 1 green F2: g1g1 Cross 2 green F2: g2g2 Cross 3 green F2: G3_ (G3G3 or G3g3) (c) If Fritz were to cross the F 1 from cross 2 (i.e. from yellow x green 2) with parental green strain 2, what phenotypic ratio should he expect in the progeny of that cross? 15 points The cross is G2g2 x g2g2. The progeny should be yellow (G2g2): green (g2g2) in 1:1 ratio. FINAL EXAM KEY 2
Image of page 2
(d) Fritz crosses a plant from green strain 1 to a plant from green strain 2. He finds the F1 from this cross all have yellow seeds. Fritz allows the F 1 to self fertilize and counts the seeds of the F 2 . He finds that 71 plants have yellow seeds and 57 have green seeds. Devise an explanation for these results, stating the type of genetic interaction and drawing out the genotypes and phenotypes of the F 2 in a Punnett square. 25 points Green 1 and 2 must be recessive mutations in two different genes, as they complement (F1 are yellow). The segregation resembles a 9:7 ratio, suggesting recessive epistasis (10 points for stating this) in which G1_G2_ are yellow, g1g1__ and ___g2g2 are green. 15 points for a correct Punnett Square FINAL EXAM KEY 3
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Question 2 In Drosophila, mutations in the genes sable (s), garnet (g) and forked (f) confer black bodies, lightly pigmented eyes, and forked bristles, respectively. These three genes are X-linked. Females heterozygous for mutations in s , g and f are phenotypically wild type. You cross these parental females with wild type males and obtain the following F 1 male progeny classes (classified by phenotype): Progeny class Phenotype Number of flies Genotype I sable garnet, forked 445 s g f II wild-type 435 + + + III sable forked 145 s f IV garnet 135 g V sable garnet 1855 s g VI forked 1965 f
Image of page 4
Image of page 5
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern