BI226 Lecture Notes - Lecture 3: Starch, Chlorophyll, Sucrose

33 views4 pages

orchidcicada598

1 Nov 2016

School

Department

Course

Professor

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

Document Summary

Genotypes in f2 progeny are 1:2:1 (1/4 yy, 1/2 yy, 1/4 yy) Phenotypes in f2 progeny are 3:1 ratio (3/4 yellow, 1/4 green) A testcross can reveal can reveal an unknown genotype. Take an individual with unknown genotype, cross with homozygous recessive. If yellow can only be produced: homozygous dominant. If both types can be produced: heterozygous dominant. Mendel tested whether two genes in dihybrids would segregate independently. First, he crossed true-breeding yellow round peas with true-breeding green wrinkled peas to obtain dihybrid f1 plants: Yy rr x yy rr = yy rr. Then, the dihybrid f1 plants were crossed to itself to obtain f2 plants: F1 yy rr x f1 yy rr = f2. Each f1 dihybrid produces 4 possible gametes in a 1:1:1:1 ratio. Yyrr = 1/4 yr, 1/4 yr, 14 yr, 1/4 yr. Four phenotypic classes occurred in the f2 progeny. During gamete formation, different pairs of alleles segregate independently of each other.

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

Hi I am studying for a biology exam and I have some questionsthat are on a review sheet that i am unsure about

1. In Tomatoes, the allele for red fruit is dominant over theallele for yellow fruit. If a plant that is homozygous for redfruit is crossed with a plant with yellow fruit â

a) what is/are the genotype(s) and the phenotype(s) of the fruitproduced in the F1 generation?

b) what is/are the genotype(s) and the phenotype(s) of the fruitproduced in the F2 generation?

c) what is the phenotypic ratio of the F2 fruit?

2. A plant with red flowers is crossed with a plant with whiteflowers. All the F1 plants produced red flowers. When the F1 plantsare allowed to self-pollinate, they produce 623 plants with redflowers and 198 plants with white flowers. What are the genotypesof the P and F1 generations?

3. In Tomatoes, the allele for red fruit isdominant over the allele for yellow fruit. Theallele for tall plants is dominant of the allele forshort plants. Find the genotypes and phenotypes ofthe F₁ and F₂ generations and the phenotypicratio of a cross between a homozygous dominant in both genes and ahomozygous recessive in both genes. The homozygous individuals arethe Parental generation.

4. In cocker spaniels, solid coat color is dominantover spotted coat. A veterinarian has a spaniel with a solidcoat. How can she unequivocally determine the genotype of thisanimal for coat color from a single breeding?

rubyserval737

Diagram a cross between a true breeding pea plant that produces yellow seeds (G/G) with one that produces green seeds (g/g). Carry the cross out to the F2 generation. Answer the following questions:

What was the F1 genotype and phenotype?

What kinds of gametes could the F1 individuals produce?

What were the F2 genotypes and phenotypes, and in what ratios would you expect each to occur?

Diagram a cross between a true breeding pea plant that produces round seeds and purple flowers, with one that produces wrinkled seeds and white flowers. (Round and purple are the dominant traits.) Carry the cross out to the F2 generation. Answer the following questions:

What are the P1 genotypes?

What is the F1 genotype and phenotype?

What kinds of gametes will the F1 individuals produce?

What are the F2 genotypes and phenotypes?

What genotypic and phenotypic ratios are expected in the F2 progeny?

Diagram a cross between a true breeding pea plant that produces yellow seeds (G/G) and purple flowers (W/W) with one that produces green seeds (g/g) and white flowers (w/w). Carry the cross out to the F2 generation. Answer the following questions:

What was the F1 genotype and phenotype?

What kinds of gametes could the F1 individuals produce?

What were the F2 genotypes and phenotypes, and in what ratios would you expect each to occur?

Diagram a test cross of the F1 individuals from the question above, with the homozygous recessive parent strain. What genotypes and phenotypes would you expect in the testcross progeny, and in what ratios?

If you had a fruitfly with phenotype A, what test would you make to determine if it was Aa or AA? Explain the different outcomes expected if the fly in question is AA or Aa.

If individuals of genotype AaBbCc are intercrossed:

How many different genotypes can occur in their progeny? How many different phenotypes can occur in the progeny?

orangecrow253

BI226 Lecture Notes - Lecture 3: Starch, Chlorophyll, Sucrose

Document Summary

Get access

Related Documents

BI226 Lecture Notes - Lecture 4: Mendelian Inheritance, Punnett Square, Zygosity

BI226 Lecture Notes - Lecture 16: Dihybrid Cross, Product Rule, Gamete

BI226 Lecture Notes - Lecture 2: Lethal Allele, Hh Blood Group, Allele Frequency

Related Questions