BIOL 1201 Lecture Notes - Lecture 19: Dihybrid Cross, Mendelian Inheritance, Phenotype

27 views2 pages

beigeelk160

16 Nov 2016

School

Department

Course

Professor

For unlimited access to Class Notes, a Class+ subscription is required.

Document Summary

Mendel"s second law, principle of independent assortment: (non-homologous chromosomes) F2 results: phenotypes and genotypes (if on non-homologous chromosomes) seed form and seed color. R/r y/y r/r y/y phenotypes round, yellow wrinkled, yellow round, green wrinkled, green. Note new non-parental combinations (wrinkled, yellow and round, green) If we do the same dihybrid cross, we did above. Mendel"s observation: no new non-parental combinations phenotypic ratio: 3 smooth, yellow: 1 wrinkled, green (3:1 ratio for each trait) Conclusion: this result from 2 separate and independent monohybrid crosses. Product law the chance that a number of independent events will occur together is equal to the product of the chances that each will occur separately. Genes that are one the same chromosomes. You only get 1 allele from 1 parent. Because they are on the same chromosome (linked) [clicker]: a rooster with gray feathers is mated with a hen of similar phenotype: among the offspring: 15 gray, 6 black, 8 white.

Related Questions

You recently discovered a new variety of sweetpea plants in the area surrounding Chernobyl that cannot be crossedwith the sweet pea plants used in Mendel's experiments. Youidentify several pure breeding strains with characteristics thatare similar to those described by Mendel. You found that round (R)was dominant over wrinkled (r) for pea shape and yellow (Y) wasdominant over green (y) for pea colour in monohybridcrosses.

(a) show the expected outcome of a dihybridcross starting with pure breeding plants with round yellow peas andpure-breeding wrinkled green peas. Include all phenotypes and thecorresponding genotypes for parental, F1 and F2 generations. Alsoinclude the expected phenotypic ratios for the F2 generation.Surprisingly, when you performed this cross, you notice someinteresting differences from Mendel's experiments. Although all F1progeny had round yellow peas, the F1 self cross resulted in farfewer round green and wrinkled yellow peas than expected. Beingvery clever, you hypothesize that these loci may be linked in thisvariety of pea and you performed a testcross between F1 plants anddouble homozygous plants with wrinkled green peas. You obtained thefollowing progeny: 445 Round yellow, 48 round green, 52 wrinkledyellow and 455 wrinkled green. (b) Identify the parental andrecombinant classes from the test cross (2 marks). (c) Estimate therecombination frequency using these data, and show your work. (d)Indicate the distance between loci in map units, and show yourwork. (e) Using the recombination frequency you calculated in (c),predict the phenotypic ratio in the F2 generation in the dihybridcross in (a)

goldpanda491

1. Ifa species of flower has the allele R (red) which is incompletelydominant to the allele r (white) what color is the genotype of anindividual with a red flower? Choose as many as areappropriate. (Points: 2) RR
Rr
rr
R
r

2. A gene can be defined as... (Points :2)

alternateforms of the DNA for a trait
geneticcombination that determines the observable form of a trait
partof the DNA that codes for a specific protein
theobservable form of a trait

3. A homozygote is an individual in which(Points : 2)

allelesof the gene pair are different
allelesof the gene pair are identical
genesare homolgous
traitsare passed from parents to progeny

4. Which of the following might be aphenotype? (Points : 2)

A
Aa
pinkflowers
AaDd

5. What does "F2 generation" refer to? (Points: 2)

theparents
theoffspring of the parental generation
theoffspring of crossing the F1 generation with itself
theoffspring of crossing the F1 generation with the parentalgeneration

6. Which of the following genotypes isheterozygous? (Points : 2)

Aa
AABB
A
a

7. Which statement best describes a dominantallele? (Points : 2)

theallele expressed in the homozygote
theallele expressed in the heterozygote
theallele that is most common in the population
theallele that is lethal