BIO 2133 Chapter 2: Module 4B_4C notes

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9 Mar 2017

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Vocabulary: homozygous: genotype has two of the same allele, aa = homozygous dominant, aa = homozygous recessive, purebred = homozygous, heterozygous: genotype has two different alleles, aa = heterozygous, one dominant and one recessive, hybrid = heterozygous. Monohybrid crosses: monohybrid crosses are used to predict the outcome of just one trait, the genotypes of both parents must be known, paternal father, maternal mother. Dihybrid crosses: dihybrid crosses are used to predict two traits at the same time, first step is to find all possible allele combinations, the rules for filling in the punnett square are the same as before. Guessing sheep phenotypes: white sheep must be bb, black should can be bb or bb, we don"t know, can use test cross to guess. Test cross: by crossing the white and black sheep, we can determine the genotype of the black sheep by the phenotypes of their offspring, with other ones, always cross with a recessive individual.

Related Questions

When a parent who is heterozgyous for a trait is crossed with a parent who is heterozygous for a trait, the offspring will:

(remember homozygous means two of the same alleles and heterozygous means two different alleles)

Select one:

a. have 3 out of 4 the dominant phenotype and 1 out of 4 the recessive phenotype

b. have 2 out of 4 the dominant phenotype and 2 out of 4 the recessive phenotype

c. all have the dominant phenotype

d. have 1 out of 4 the dominant phenotype

When a parent who is heterozgyous for a trait is crossed with a parent who is homozygous dominant for a trait, the offspring will:

(remember homozygous means two of the same alleles and heterozygous means two different alleles)

Select one:

a. all have the recessive phenotype

b. all will have the dominant allele

c. all be homozygous dominant genotype

When a parent who is heterozgyous for a trait is crossed with a parent who is heterozygous for a trait, the offspring will:

(remember homozygous means two of the same alleles and heterozygous means two different alleles)

Select one:

a. have 3 dominant phenotypes, 2 heterozygous genotypes, and 1 homozygous recessive genotype

b. have 1 dominant phenotype, 2 heterozygous genotypes, and 1 homozygous recessive phenotype

c. have all dominant phenotypes, 2 heterozygous genotypes, and 1 homozygous recessive genotype

When doing Punnett squares for fur, the letter f represents ______ and the letter F represents _____.

Select one:

a. the recessive allele, the dominant allele

b. the dominant allele, the recessive allele

c. the dominant gene, the recessive gene

d. the recessive gene, the dominant gene

10.

When a parent who is heterozgyous for a trait is crossed with a parent who is homozygous recessive for a trait, the offspring will:

(remember homozygous means two of the same alleles and heterozygous means two different alleles)

Select one:

a. be half heterozygous and half homozygous recessive

b. be all heterozygous

c. be all homozygous recessive

d. be all homozygous dominant

Please assist with the following. Please no hand-written work, but typed work and thorough explanations please including Punnett Squares. Please Ignore Sex, as these are not sex-linked traits

Dihybrid Testcrosses

In the following crosses, the wild trait is dominant and the brown trait for eye color and ebony trait for body color are both recessive. You will compare the offspring of homozygous wild flies to the offspring of heterozygous wild flies, when each is crossed with a recessive brown-eyed fly with an ebony body.

7. Perform a monohybrid cross between a wild-type female fly and a male fly with brown eyes and ebony body.
Show results for the F₁ offspring. (NOTE: You will use one of these F₁ flies in the next cross.)
ENTER DATA HERE:

PUNNETT SQUARE:

List the genotypes of the flies in this cross:

List the gametes produced by each fly in this cross:

Show the Punnett Square for the above cross.

Question: By examining the offspring, determine whether the wild-type female parent was homozygous or heterozygous for eye color and body color. How did you arrive at this conclusion?

Question: Are the F₁ offspring homozygous or heterozygous for eye color and body color? How did you arrive at this conclusion?

8. Now perform a cross between one wild-type F₁ offspring from the previous cross and a male fly with brown eyes and ebony body.
ENTER DATA HERE:

PUNNETT SQUARE:

List the genotypes of the flies in this cross:

List the gametes produced by each fly in this cross:

Show the Punnett Square for the above cross.

Question: Even though you already knew the genotype of the wild-type fly used in this cross, how can you tell by examining the offspring of this cross whether the wild-type fly in this cross was homozygous or heterozygous for eye color?

Question: What was the phenotypic ratio for the offspring resulting from this testcross?

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

BIO 2133 Chapter 2: Module 4B_4C notes

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