BIO 200 Lecture Notes - Lecture 6: Zygosity, Phenotype, Quantitative Trait Locus

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rubymammoth292

24 Oct 2018

School

University at Buffalo

Department

Biological Sciences

Course

BIO 200

Professor

All

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Document Summary

Mendel"s 1st law/segregation- 2 alleles segregate during gamete formation (1 from each parent) to be rejoined at random during fertilization. Allows for later expression of latent traits. Where are the gametes on a punnett square?- on outside edges. Can you determine the parental genotypes from a. Phenotype vs. genotype ratios- 3:1 vs. 1:2:1. Dihybrid crosses- cross between 2 organism that are hybrid (heterozygous) for two traits. Can you find the gametes and parental phenotypes from a dihybrid punnett square?- Rryy x rryy rryy ry, ry, ry, ry. Mendel"s 2nd law/independent assortment- in dihybrid cross, alleles of each gene assort independently. Gene linkage- genes on same chromosome; only show phenotypes of parents!!! Two state cases vs. multi-state cases- all of mendel"s traits were 2 state cases (aka tall and short); but many traits are much more complicated than this. Polygenic inheritance- more than 1 gene controls traits additively to affect phenotype. Varies across a range i. e. plant height.

Related Questions

Question 1

What would be the dimensions of a Punnett square for the cross Hh x hh?

		4 x 4
		2 x 2
		2 x 1
		1 x 1

Question 2

In dogs, the gene for fur color has two alleles. The dominant allele (G) codes for grey and the recessive allele (g) codes for black fur. The female dog is heterozygous. The male dog is homozygous recessive. Figure out the phenotypes and genotypes possible in their puppies by using a Punnett Square. (provide answers on one line with commas between - xx, xx, xx, xx)

Genotypes: , ,

Phenotypes: ,

Question 3

The fundamental Mendelian process which involves the separation of alleles located at the same spot on the chromosome would be called ___.

		segregation
		independent assortment
		continuous variation
		discontinuous variation

Question 4

Using the information given on dominant and recessive traits, state the phenotype for each genotype. Purple flowers are dominant to white flowers in pea plants.

-A.B.C.	PP_____________
-A.B.C.	Pp____________
-A.B.C.	pp_______________

A.	purple flowers
B.	purple flowers
C.	white flowers

Question 5

In dogs, the gene for fur color has two alleles. The dominant allele (G) codes for grey and the recessive allele (g) codes for black fur. The female dog has black fur and the male dog is homozygous dominant. Make a Punnett square to determine the chance of getting each genotype and phenotype below.

-A.B.	Probability of GG:
-A.B.	Probability of Gg:
-A.B.	Probability of gg:
-A.B.	Probability of gray fur:
-A.B.	Probability of black fur:

A.	100
B.	0

Question 6

Using the information given on dominant and recessive traits, state the phenotype for each genotype. Round seeds are dominant to wrinkled seeds in pea plants.

-A.B.C.	RR______________
-A.B.C.	Rr _____________
-A.B.C.	rr ____________

A.	round seeds
B.	wrinkled seeds
C.	round seeds

Question 7

Using the information given on dominant and recessive traits, state the phenotype for each genotype. Hairy knuckles are dominant to non-hairy knuckles in humans.

-A.B.C.	HH_____________
-A.B.C.	Hh ___________
-A.B.C.	hh _________________

A.	non-hairy knuckles
B.	hairy knuckles
C.	hairy knuckles

Question 8

An allele is ___.

		one of the bases in DNA
		an alternate form of a gene
		another term for epistasis
		present only in males and is responsible for sex determination

Question 9

In a cross of a round hybrid pea with a true breeding round parent (Rr x RR), what genotypic proportions would be observed in the offspring?

		Half heterozygous, half homozygous dominant
		Half round, half wrinkled
		All heterozygous
		All round

Question 10

What would be the dimensions of a Punnett Square depicting a dihybrid cross?

		1 x 4
		2 x 4
		4 x 4
		2 x 2

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

QUESTION 1

If Plant 1 has a genotype of YY and Plant 2 has a genotype of yy, what is Plant 1's phenotype (the physical appearance of the plants' seeds)?

0.5 points

QUESTION 2

If Plant 1 has a genotype of YY and Plant 2 has a genotype of yy, what is Plant 2's phenotype (the physical appearance of the plants' seeds)?

0.5 points

QUESTION 3

What are the possible genotypes for offspring between Plant 1 and Plant 2?

1 points

QUESTION 4

What are the possible phenotypes for offspring between Plant 1 and Plant 2?

1 points

QUESTION 5

Now, trade one allele between plants such that each is heterozygous for the color trait. Fill in the Punnett Square below, with one plant's allele's in the dark boxes along the top, and the other plant's alleles in the dark boxes along the left.

1.5 points

QUESTION 6

What are the possible genotypes for offspring between Plant 1 and Plant 2?

, ,

0.5 points

QUESTION 7

What percentage of offspring would you expect to have each genotype?

YY %

Yy %

yy %

1 points

QUESTION 8

What are the possible phenotypes for offspring between these two plants?

1 points

QUESTION 9

What percentage of offspring would you expect to have each phenotype?

Yellow %

Green %

1 points

QUESTION 10

Mendel developed his Law of Segregation after observing two generations of crossed pea plants. His first generation plants were homozygous(as were yours). The second generation of crossing happened between two heterozygous plants (as in Question 5).

Imagine that the prevailing hypothesis of the time is that traits from the mother and father tend to blend together in offspring. Why did the results of Mendelâs experiment prompt him to come up with the Law of Segregation instead?

BIO 200 Lecture Notes - Lecture 6: Zygosity, Phenotype, Quantitative Trait Locus

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