BIOL 2153 Chapter : HW 4

29 views8 pages

azuremammoth471

15 Mar 2019

School

Department

Course

Professor

For unlimited access to Textbook Notes, a Class+ subscription is required.

Document Summary

Answer keys answers are generally underlined and/or shown in bold font. Biol 2153, sections 1-4, dr. foltz, principles of genetics, spring 2012 homework #6: the following information represent the transmission of x-linked allele drosophila. The genotype of each fly are given and alleles linked on one chromosome are separated from alleles linked on the other chromosome by / . F2 males genotype recombinant/parental female w+y/wy+ x male wy+/y wy+/y wy/y w+y+/y w+y/y. Parental: can we determine in the gamete of which parent the cross-over occurred. Yes, the crossover occurred in the f1 female, because the y chromosome in the f1 male does not carry the w and y genes. Be sure to distinguish between the y chromosome and the y mutant: in drosophila male with yellow body, extra bristle, and forked bristle is crossed with a female with curly wings. In the f1 generation both male and female offspring are all completely normal.

Related Questions

1. The eye color of wild-type Drosophila flies is red. Differentmutations in a single or in multiple genes lead to flies with whiteeyes. Mutations in the w gene on the X chromosome lead to whiteeyes instead of the normal red. You have isolated both a white-eyedmutation (designated W-1) that gives a dominant phenotype, and awhite-eyed mutation (designated w-2) that gives a recessivephenotype.

(a) A white-eyed male from the W-1 line is crossed to awild-type female. What color eyes will the female progeny from thiscross have?

(b) What color eyes will the male progeny from the cross in part(a) have?

(c) One of the female progeny from the cross in part (a) ismated to a white-eyed male from the w- 2 line. What fraction of thewhite-eyed progeny from this cross will be female?

2. The body color of Drosophila adult flies is regulated bymultiple genes, including the autosomal ebony gene. Ebony body (e)is recessive to the wild type (yellowish) body (e+). A second gene,which is X-linked, controls bristle shape. Normal bristle shape(f+) is dominant to the mutant forked bristles (f). A female withforked bristles that is heterozygous for the body color gene ismated with an ebony body male (his bristles are normal).

(a) What are the genotypes of the parents?

(b) Using a Punnett square, determine the expected proportionsof each possible progeny phenotype. Since there is a sex-linkedgene here, be sure to include consider sex as part of thephenotype.

3. Describe in your own words what a balancer chromosome is andwhy it is important in fly genetics (you will have to do someresearch for this one!)

mauvepug893

Chromosome Mapping (determining the relative positions of genes on a chromosome) - This is a two point cross since it involves two loci on a chromosome.

Follow the directions for the crosses below involving 2 traits located together on the same chromosome (Drosophila Chromosome IV): eyeless and shaven bristles. Please only typed answer, no hand-written work or screen shots please.

1. a. Perform a monohybrid cross between a female fly with the eyeless mutation and a male fly with shaven bristles. Show results for the F₁ offspring. (NOTE: You will use an F₁ female in the next cross.)
ENTER DATA HERE:

Question: Are the phenotypes of the F₁ offspring what you would have predicted for this cross: why or why not?

Question: After looking at your F₁ offspring, which allele is dominant: wild-type eyes or eyeless? How can you tell?

Question: After looking at your F₁ offspring, which allele is dominant: wild-type bristles or shaven bristles? How can you tell?

Draw the Chromosome IV pair of an F₁ offspring: (HINT: One chromosome was inherited from the mother, with the eyeless allele at the eye shape location (locus) and the wild-type allele at the bristles locus. The second chromosome was inherited from the father, with the wild-type allele at the eye shape locus and the shaven bristle allele at the bristles locus.)

1. b. Perform a testcross between an F₁ female offspring from the previous cross and a new male with both the eyeless and the shaven bristle traits to produce an F₂ generation.
ENTER DATA HERE:

Question: What phenotypes are found in the F₂ offspring?

Question: Are the phenotypes of the F₂ offspring what you would have predicted for this cross: why or why not?

Draw the 2 different Chromosome IV pairings you expected in an F₂ offspring: (HINT: The F₁ female will donate one or the other of the chromosomes you drew above to each offspring. The new male with both the eyeless and the shaven bristle traits can only donate one type of chromosome, with both mutations.)

Question: What are the 2 phenotypes that would result from the 2 different chromosome pairings you just drew?

Question: What are the other 2 phenotypes that you obtained in your F₂ offspring? What process, which occurred during meiosis, was responsible for the creation of these recombinant phenotypes?

Draw a map that shows the map distance (in map units or centimorgans) between the locus for the shaven bristle allele and the locus for the eyeless allele. (NOTE: You need to add the proportion of SV;EY flies to the proportion of wild flies OR add the number of SV;EY flies and wild flies and then divide by the total number of flies. Then multiply either number times 100.)âSHOW ALL CALCULATIONS BELOW

CALCULATIONS:

CHROMOSOME MAP:

There are several different ways to draw maps of the chromosomes. You can draw a simple line graph using a free online graphing tool, such as:

http://www.onlinecharttool.com/

http://nces.ed.gov/nceskids/createagraph/

Or you can simply use your keyboard to create a line with the dash or underline, with the abbreviations for the genes inserted, and then put the map units below, such as:

___________A_____________________B_________

50 map units

Answer the following Linked to sex genetics problems:

1.) In Drosophila the recessive mutation linked to the X chromosome, scalloped ( sd ), causes the edge of the wings to be irregular. Present the results (you must prepare the crossing scheme) phenotypic for F1 and F2 for a cross between:

A) female scallop and a normal male (regular edges)

B) A normal (homozygous) female and a scallop male .

C) Compare these results with those that would be obtained if scallop were an autosomal recessive mutation.

2.) In Drosophila the autosomal recessive ebony mutation (e) is located on chromosome 3 and produces a dark body in the fly that expresses it. What will be the phenotypic proportions for F1 and F2 that will be obtained from a cross between a scallop female and homozygous for a normal body, with an ebony male with normal wings? Solve by the bifurcated lines method.

3.) In Drosophila the recessive mutation linked to the vermilion X chromosome (v) produces bright red colored eyes in contrast to the wild phenotype that has brick red eyes. An autosomal recessive mutation, suppressor vermilion (su-v) causes homozygous or hemizygous males to females present vermilion red brick eyes. In the absence of the vermilion allele su-v has no effect on the phenotype of the eye. Determine the genotype and phenotype of F1 and F2 at a cross between a homozygous female for vermilion and su-v, with a vermilion male and wild homozygous for su-v (su-v + su-v + ) . Present the diagram of bifurcated lines for these crosses.

4.) At a crossroads with Drosophila involving recessive mutations white (linked to the X chromosome) and sepia (autosomal recessive) that produces dark eyes, predict the results of F1 and F2 when crossing pure parents with the following phenotypes.

A.) White females with sepia males.

B.) Sepia females with white males

5.) Two mothers have given birth to their children at the same time in an urban hospital with an excess of patients. The child of couple 1 has hemophilia, a condition caused by a recessive allele linked to the X chromosome. Neither parent has the condition. Couple 2 has a normal child even though the father is a hemophiliac. Several years later, couple 1 filed a lawsuit alleging that the babies were changed after birth and you are called to testify as a genetic counselor. What information would you give the jury in relation to the allegation of the couple 1?

BIOL 2153 Chapter : HW 4

Document Summary

Get access

Related Documents

BIOL 2153 Chapter : Snu6e Qp Ch05 Bcs

BIOL 2153 : Test One Practice Questions Genetics

BIOL 2153 : Cumulative Final Exam Practice Tests

Related Questions