BIOL 111 Lecture Notes - Lecture 14: Dihybrid Cross, Zygosity, Chromosome

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azuredog326

27 Aug 2016

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Document Summary

Homozygous: an organism with two identical alleles for a gene. Heterozygous: an organism with two different alleles for a gene. Unlike homozygous, heterozygotes are not true breeding. An organism"s traits do not always reveal its genetic composition because of the different effects of dominant and recessive alleles. Carry out a testcross to tell the genotype of an individual with the dominant phenotype. Testcross: breeding the mystery individual with a homozygous recessive individual. If any offspring display the recessive phenotype, the mystery parent must be heterozygous. Mendel derived the law of segregation by following a single character. The f1 offspring produced in this cross were monohybrids, individuals that are heterozygous for 1. Mendel identified his 2nd law of inherit by following 2 characters at the same time. Crossing 2 true-breeding parents differing in2 characters produces dihybrids in the f1 generation, heterozygous for both characters.

Related Questions

1. A person is described as a carrier for a particular genetic disease. What does this tell you about their genotype?

2. For any given gene, the principle of independent segregation predicts that each gamete produced as a result of meiosis will contain ____________________

3. A pair of alleles is said to be heterozygous when:

4. In a diploid species, cells can have up to ___ alleles of a particular gene.

5. In a cross between a homozygous dominant parent and a homozygous recessive parent, the number of phenotypic classes observed in the offspring is ______

6. For a person of genotype Xx, the genotype of their gametes may be ______________

7. In a "test cross", an individual of unknown genotype is crossed with a ___ individual to determine the unknown genotype.

8. An albino woman has a child with a phenotypically normal man with no family history of albinism (which is a rare recessive disorder). What percentage of their children are likely to be albino?

9. An individual with the dominant phenotype, but an unknown genotype, is test-crossed, and all of the offspring exhibit the dominant phenotype. The genotype of the unknown individual is ______________

10. If two heterozygous individuals for a recessive disease (carriers) have a child, what is the chance that their child will develop the disease?

11. In a monohybrid cross between two true-breeding parents that both exhibit the dominant phenotype, ___ percent of the offspring will exhibit the recessive phenotype.

12. In a particular type of tomato plant, red fruit is dominant over yellow fruit, and dwarf height is a recessive trait. If two heterozygous plants were crossed, what proportion of the offspring would show the dominant phenotype?

13. In a cross between a BbRr individual and a BBRR one, what do the following represent: BR, Br, bR, br?

14. In humans, the gene that determines whether an embryo develops as a male or a female is carried on _____________

amaranthhare726

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.