BISC207 Lecture Notes - Lecture 12: Mendelian Inheritance, Pleiotropy, Y Chromosome

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fuchsiamanatee804

5 Dec 2017

School

University of Delaware

Department

Biological Sciences

Course

BISC207

Professor

David Raden

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What are the chances of having a boy and then two girls- 1/8. What are the chances of having a boy and two girls- 3/8. Principles of segregation: pairs of alleles are separated during meiosis i in the formation of gametes. X linked- determines the sex of the o spring. Meiosis in females results in x- bearing eggs only. Meiosis in a mae results in a 1:1 ratio of x- bearing and y- bearing sperm. Random fertilization results in an expedited ration of 1/2 xx(female) and 1/2 xy(male) progeny. Reciprocal cross is two separate crosses of 2 phenotypes for5 a trait where the di erence between the 2 crosses is the sex of each phenotype. You cross a heterozygous smooth pea (rr) to a wrinkled pea (rr). You know that the r gene is autosomal. Both will produce half smooth and half wrinkled peas. Males and females are equally likely to.

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

âThe wrinkled seed character that Mendel studied was R versus r on l inkage group V. The character âgreen versus yellow podâ is unambiguously Gp versus gp , also on linkage group V. Linkage between these two loci can be detected. In Mendelâs study of two- and three- factor crosses he used approximately 600 F 2 individuals. He did not present data on the combination of RR Gp Gp crossed with rr gpgp â¦ [When] lines JI15 and JI399 [ are crossed ], the recombination fraction between the R locus â¦ and Gp is 36 %, resulting in an expected segregation ratio of 9 . 6 : 2.4 : 2.4 : 1 . 6 rather than 9 : 3 : 3 : 1. Mendel would have needed about 200 plants in the âsmaller numberâ to have a 5 % statistically significant deviation from independent assortment.

Furthermore, linkage group V in pea, most likely corresponding to chromosome 3 , behaves unusually in this cross because the number of chiasmata is never greater than one; usually two or three occur. The recombination fraction calculated above is therefore the smallest that Mendel could have encountered, so it is unlikely that genetic l inkage would have been discernable in any of the crosses that Mendel examined. â

â¢ Explain the 9.6:2.4:2.4:1.6 ratio expected with a 36% recombination between the R and Gp loci in the cross between lines JI15 X JI399.

Hints: (i) What extent (%) of recombination would give you a perfect 9:3:3:1 ratio? (ii) You may consult the Hall et al. (1997) paper if necessary (file [6] in Minicourse 1 folder).

â¢ Does the number of chiasmata (two or three in many other Pisum sativum cultivars but 1 or 0 in the JI lines) explain Mendelâs results? Hint: What are chiasmata? What is their genetic function?

â¢ Can we still trust Mendelâs conclusions about independent segregation of characters?

BISC207 Lecture Notes - Lecture 12: Mendelian Inheritance, Pleiotropy, Y Chromosome

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