BIOL 401 Lecture 1: Basic of Genetics

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greenfly749

4 Feb 2017

School

Binghamton University

Department

Biology

Course

BIOL 401

Professor

Steven P Tammariello

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Document Summary

Gregor mendel crossed peas to observe phenotypes and genotypes between generations. Dihybrid cross: looking at two things, such as color and shape: 9:3:3:1 ratio. Not possible to predict the dna of an organism based on the phenotype only unless you perform a cross. The phenotype of the f1 generation resembles the dominant trait if the p generation are homozygous recessive and homozygous dominant. Incomplete dominance: the phenotype of the heterozygous f1 generation is a combination of both the dominant and recessive phenotypes of the p generation. Neither parental allele is dominant or recessive. F2 generation will produce a mixture of pink, red, and white flowers. Co-dominance: both dominant and recessive alleles are expressed equally, causing the offspring"s phenotype to be a mixture of the alleles expressed, where in incomplete dominance it"s more of a. Different from incomplete dominance in that both traits are blending of phenotypes. F1 generation takes characteristics from both parents.

Related Questions

Problem A. You cross two homozygous parents: RRYY (round yellow) and rryy (wrinkled green) to produce an F1 generation. Round seeds are dominant, yellow seeds are dominant. You cross two F1s to produce the F2 generation. In the F2 generation, you find an individual with round yellow seeds. You do a testcross to find out the genotype of this âmysteryâ dominant/dominant phenotype. In the offspring of the cross, you find 1?2 have round yellow seeds and 1?2 have wrinkled yellow seeds.

1. Based on these data what was the genotype of the mystery F2?

Problem B. You carry out a dihybrid cross between a red-flowered rose with long pollen grains (A1A1 LL) and a white-flowered rose with round pollen (A2A2 l l). The flower color gene (A) shows incomplete dominance, and long pollen is completely dominant to round pollen. The genes for these traits are on different chromosomes so assort independently

2. What would be the phenotypes of the F1 generation?

3. What fraction of the F2 generation is expected to have red flowers and long pollen? (As always when traits are independent, what rule can you apply to save time?)

Problem D. In the example of epistasis presented in class, the agouti allele in mice (A) codes for striped hairs and is dominant to the allele for all black hairs (a). A loss-of-function allele for the pigment gene (b) produces no pigment and is recessive to the normal, dominant allele (B). The recessive allele at b masks the effect of the A gene. A dihybrid cross of AABB and aabb is carried out.

5. Name all of the genotypes in the F2 generation that can produce an albino (no pigment) phenotype.

Problem E. A cross is made between homozygous fruit flies that differ for eye color (the st gene) and

body color (the e gene). The F1 double heterozygote is shown below using chromosome notation.

st+ e

--------------------------------------

st e+

st = the recessive allele for scarlet eyes; st+ = the dominant wildtype allele for red eyes e = the recessive allele for ebony body; e+ is the dominant wildtype allele for gray body

6. Are the chromosomes shown in the genotype above in cis or trans configuration?

7. Based on this notation, what were the genotypes and phenotypes of the two parents of the F1? (Think carefully here...)

8. With what phenotype would you cross this F1 to measure recombination frequency?

cyansnail823

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

BIOL 401 Lecture 1: Basic of Genetics

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