BIOL 1201 : SI Exam 5 Review

6 views8 pages

azuremammoth471

15 Mar 2019

School

Department

Course

Professor

For unlimited access to Study Guides, a Grade+ subscription is required.

Document Summary

Linked genes - genes located on the same chromosome. Since there is no independent assortment (the genes move together), the 9:3:3:1 ratio is not seen when crossing two heterozygous individuals. Wild-type- usual phenotype, dominant (w+) mutant - unusual phenotype; recessive (w) Did another cross between heterozygous wild-type flies and homozygous mutant flies results in 2 parental types and 2 new types that are different from parents. Shift toward parental phenotype was due to linkage of genes. Recombination - new combination of genes in the offspring that are different from the parental combinations. Recombination frequency can be used to determine map units: recombination between linked genes are due to crossing over. Xy system sex is determined by male gamete. Exam 5 review: male is xy - heterogametic, female is xx - homogametic. Xo system sex is determined by number of sex chromosomes: male is x - half of male gametes have no sex chromosome, female is xx.

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

3. Consider a cross between white-eyed female flies and red-eyed male flies. Importantly, the white gene is X-linked. Write out the punnett square here. Be sure to define your allele symbols then indicate the probability (a ratio is fine) of observing any one of the following phenotypes:

a. Red-eyed females _________

b. Red-eyed males _________

c. White-eyed females ________

d. White-eyed males. __________

4. You want to build a double mutant (ab/ab) between two genes, A and B, that are 10 map units apart. You first cross a/a into b/b to create the dihybrid: a+/+b. Next, you do an F1 cross and search the F2 generation for the rare double mutant: ab/ab. What percent of the progeny (offspring) will have the double mutant phenotype in the F2 generation? Show your equation. 5. EXTRA CREDIT. It should be noted that white was not the first sex-linked mutation discovered. In the currant moth Abraxus, DONCASTER and RAYNOR (1906) described a trait called lacticolor segregating among wild females but not among males. How might one explain this?

fuchsiagerbil537

In Drosophila, the map positions of genes are given in map units numbering from one end of a chromosome to the other. The X chromosome of Drosophila is 66 m.u.. long. The X-linked gene for body color-with two alleles, y ⁺for gray body and y for yellow body-resides at one end of the chromosome at map position 0.0. A nearby locus for eye color, with alleles w ⁺for red eye and w for white eye, is located at map position 1.5. A third X-linked gene, controlling bristle form, with f ⁺ for normal bristles and f for forked bristles, is located at map position 56.7. Each gene resides on the Xchromosome, and at each locus the wild-type allele is dominant over the mutant allele.

Predict the frequency of gray with white eyes and forked bristles progeny type produced by this mating.

Enter your answer as a percentage to three decimal places (example 0.235 or 0.230).

Frequency=_________

Phenotype	Number
Pale	648
Pale, oval	64
Pale, short	10
Pale, oval, short	102
Oval	6
Oval, short	618
Short	84
Wild type	98
	1630

A wild-type trihybrid soybean plant is crossed to a pure-breeding soybean plant with the recessive phenotypes pale leaf l, oval seed (r), and short height (t). The results of the three-point test cross are shown in the table. Traits not listed are wild type.

Calculate the interference value for these data.

Enter your answer to three decimal places (example 0.201).

scarletbadger940

BIOL 1201 : SI Exam 5 Review

Document Summary

Get access

Related Documents

BIOL 1201 : SI Exam 5 Review

BIOL 1201 Chapter : Biol 1201 Outline15

BIOL 1201 Chapter : Chapter 15 Outline 2017

Related Questions