Concept explainers
To estimate: The percentage of the testcross progeny a/a · b/b if the two genes are unlinked.
Introduction: The unlinked genes or genes that occur on separate chromosomes assort independently during gamete formation.
To estimate: The percentage of the testcross progeny a/a · b/b if the two genes are completely linked.
Introduction: The genes that are found on the same chromosome forms a linkage and are inherited together. This means that they are assorted in a non-independent way.
To estimate: The percentage of the testcross progeny a/a · b/b if the two genes are 10 m.u. apart.
Introduction: The map unit or the physical distance between the two genes is used to determine the percentage of recombinants that are formed after the cross. As for map unit = % recombination.
To estimate: The percentage of the testcross progeny a/a · b/b if the two genes are 24 m.u. apart.
Introduction: The map units indicate the distance between two gene loci and the recombination frequencies of the progenies.
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Introduction to Genetic Analysis
- In a variety of tomato plant ,the leaves maybe pure green,pure white,or variegated (mixture). a)when 2 variegated plants were crossed,87 offspring were produced,of these 20 were green,46 were variegated and 21 remain died soon after germination.Draw a genetic diagram to explain these results,why did 21 of them diedarrow_forward1) Short hair in rabbits (R) is dominant over long hair (r). The following crosses are carried out, producing the progeny shown. Give the most likely genotypes of the parents in each cross. (Tabulate your answers). PARENTS a) short x short b) short x long c) short x long PROGENY 4 short and 2 long 12 short 3 short and 1 longarrow_forwardIn a testcross of a corn plant heterozygous for 3 linked, recessive genes (a, b, & d), the following phenotypes & numbers of progeny were obtained (total progeny is 1000). Choose the map that best fits the data. A) A --2.7-- D --4.2-- B B) A --2.4-- D --2-- B C) A --4.2-- B --2.7-- D D) A --4.2-- D --2.7--B E) A --2-- B --2.4-- D F) A --2.7-- B --4.2-- Darrow_forward
- . a. A mouse cross A/a ⋅ B/b × a/a ⋅ b/b is made, and inthe progeny there are25% A/a ⋅ B/b, 25% a/a ⋅ b/b,25% A/a ⋅ b/b, 25% a/a ⋅ B/bExplain these proportions with the aid of simplifiedmeiosis diagrams.b. A mouse cross C/c ⋅ D/d × c/c ⋅ d/d is made, and inthe progeny there are45% C/c ⋅ d/d, 45% c/c ⋅ D/d,5% c/c ⋅ d/d, 5% C/c ⋅ D/dExplain these proportions with the aid of simplifiedmeiosis diagrams.arrow_forwardYou perform a cross between a parent with the genotype WWiiNNttEErr and another parent that is wwllnnTTeerr. All genes are unlinked except for W and I which are 22 mu apart. You take an F1 from this cross and cross it with an individual that is wwiiNntteerr. a) What is the probability that this final cross yields an offspring that is wwiinntteerr? b) What is the probability that this final cross yields an offspring that is NNTT or Nntt. (You can ignore all of the other genes for this question.)arrow_forwardYou perform a cross between two true-breeding strains of zucchini, One has green fruit and the other has yellow fruit. The F1 plants are all green, but when these are crossed, the F2 plants consist of 9 green: 7 yellow. A. Assuming that wild-type zucchini are green, how would you describe the phenomenon that occurred in the F1 of part (e) of the parents and progeny?.arrow_forward
- Two plants with white flowers, each from true-breeding strains, were crossed. All the F1 plants had red flowers. When these F1 plants were intercrossed, they produced an F2 consisting of 177 plants with red flowers and 142 with white flowers. (a) Propose an explanation for the inheritance of flower color in this plant species. (b) Propose a biochemical pathway for flower pigmentation and indicate which genes control which steps in this pathway.arrow_forwardIn fruit flies, red eyes (pr+_) are dominant to purple eyes (prpr) and normal wings (vg+_) are dominant to vestigial wings (vgvg). The genes are located on the same chromosome. A pure-breeding red-eyed fly with vestigial wings was crossed with a pure-breeding purple-eyed fly with normal wings. All of the F1 progeny had a WT phenotype. The recombination frequency between the two genes is 15%. If an F1 individual were test crossed, what percentage of the progeny would you expect to have the WT phenotype?arrow_forwardThis pedigree consist of cystic fibrosis that is an inherited disease caused by f a recessive allele. Find the genotypes of X and M? Given: O normal female □ normal male ◍ cystic fibrosis female ▨ cystic fibrosis male A) M= Ff X=Ff B) M=Ff X=ff C) M=ff X=ff D) M=ff X=FFarrow_forward
- Two linked genes, (A) and (B), are seperated by 15 cM. A man with the genotype AB/ab has children with a woman who is ab/ab. The man's father was AB/AB. a) what is the probability that their first child will be Ab/ab b) what is the probability that their first two children will both be ab/abarrow_forwardIn snapdragons, red flower color (R) is incompletely dominant over white flower color (r). The hybrids or heterozygous plants (Rr) are pink in color. a) Show the genotype for a white flower and for a red flower. b) If a red-flowered plant is crossed with a white-flowered plant, what are the genotypes and phenotypes of the F1 generation plants? c) What genotypes and phenotypes will be produced in the F2 generation? d) How did the genotypic and phenotypic ratio compare to each other in this incomplete dominance cross? e) What would the phenotypic ratio have been if this had been complete dominance? f) What kind of offspring can be produced if a red-flowered plant is crossed with a pink-flowered plant? g) What kind of offspring is/are produced if a pink-flowered plant is crossed with a white-flowered plant?arrow_forwardIn pea plants, yellow seeds (Y) are dominant to green seeds (y) and round seeds (R) are dominant to wrinkled seeds (). The genes for seed color and seed shape are on different chromosomes. Two true-breeding parents, one with yellow round peas and the other with green wrinkled peas, are crossed to produce a hybrid (heterozygous) F₁. Two F₁ individuals are crossed to give an F2; this is depicted in the Punnett square below. Place the correct genotypes in the Punnett square and the place the correct phenotypic ratios next to their appropriate phenotype on the right. YYRR YYRr YyRR YYrr yyRR yyRr Yyrr YyRr 3/16 1/16 yyrr 9/16 3/16 1/4 E 1/2 16/16 YR ✪✪✪ Yr yR YYRR Y YyRr Yr yR YR YYRr YYRR YyRr yr YyRr yyrr yr YyRr Yyrr yyRr F2 phenotype Phenotypic ratio Aarrow_forward
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