PCB 3063 Lecture Notes - Lecture 2: Genetic Linkage, Meiosis, Chromosome

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30 Mar 2017

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Genetics exam 2 outline: chapter 5: other effects on phenotypes, types of dominance a. i. Complete dominance: phenotype of the heterozygotes is the same as one of the homozygotes. Incomplete dominance: heterozygote has a phenotype in between the two alleles. Codominance: heterozygote phenotype has both dominant and recessive phenotype. Example: blood types: key terms about dominance b. i. b. ii. b. iii. Penetrance: % of individuals that express the expected phenotype. Expressivity: degree to which the phenotype is expressed. When a certain genotype kills the offspring b. iiia. b. iiib. Multiple alleles: more than 2 alleles determine trait. Example : blood groups (a,b,o: epistasis: when a certain genotype masks the phenotype of another gene c. i. Presence of ee genotype masks color phenotype in labs. B_ee is always yellow regardless of b genotype. Bombay phenotype means a person has recessive hh genotype that masks blood type (abhh) c. ia. Person has a and b alleles but neither are represented phenotypically c. ib.

Related Questions

What is the difference between incomplete dominance and codominance?

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What is the difference between incomplete dominance and codominance?

1. In incomplete dominance, the dominant phenotype is expressed in heterozygotes. In codominance, both phenotypes are expressed in heterozygotes.

2. The phenotype reveals the genotype only in codominance.

3. In both types of inheritance, the heterozygotes express the phenotypes dictated by both alleles.

4. In codominance, both phenotypes are expressed in heterozygotes. In incomplete dominance, the heterozygote shows a phenotype that is intermediate between the two homozygotes.

QUESTION 1

Jim is blood type A, his brother John is type O and his sister Jane is type AB. What are the genotypes of their parents?

Which of the following is true for alleles that show incomplete dominance?

Heterozygotes have a genotype like the dominant allele.

Homozygotes have a genotype like the recessive allele.

Heterozygotes have a phenotype intermediate between the dominant and recessive alleles.

Homozygotes have the same phenotype as the heterozygotes.

QUESTION 3

Which principle of inheritance concluded that when games are formed in meiosis, the two alleles of each gene separate from one another, and each gamete receives only one allele?

independent assortment

Which term best describes a condition in which alleles at one locus can alter the expression of alleles at another locus?

polygenic inheritance

A single unit of genetic information located on a chromosome defines:

The physical expression (appearance or function) of an organism's genes defines:

genotype

a single characteristic

Palomino horses (golden color with a blond mane) are an incompletely dominant trait produced by the combination of the chestnut color allele and the cream color allele. If you wanted to produce as many palominos as possible, which mating strategy below would be the best choice?

Which term best describes the effect of a single gene on multiple aspects of the phenotype?

polygenic inheritance

QUESTION 9

Which term best describes the separate expression of both alleles for a single trait in the same cell?

polygenic inheritance

QUESTION 10

One form of a gene found on a single chromosome defines:

A chocolate lab (whose mother was a yellow lab) is mated with a black lab whose genotype is BbEe. What fraction of the offspring would be expected to be yellow labs?

What type of allele is always expressed regardless of whether the individual is homozygous or heterozygous for it?

Both the dominant and recessive alleles

Given the parents AABBGgHhrr Ã AabbGgHhRr, assume simple dominance and independent assortment. What proportion of the progeny will be expected to have the genotype AaBbggHHrr?

___________________ is defined as having two of the same type of allele for a particular trait.

The physical position of an allele on a single chromosome defines:

Which term best describes two or more genes affecting the phenotype in an additive fashion?

codominance

polygenic inheritance

GENETICS : You perform a dihybrid cross between two dogs that are each BbFf. Where not specified otherwise, assume black fur B is completely dominant to white fur b and furry F is completely dominant to hairless f

1. What genotypes at one locus will be epistatic to what genotypes at the other locus, if hair color and hair presence were the only measured phenotypes? (you may find it helpful to write out the genotypes and the phenotypes each would produce, and remember that epistasis is involved in this question).

What phenotypic ratios would you expect in the following scenarios (assume, unless otherwise noted, that the epistasis in part 1 still applies)?

2. Black B is completely dominant to albino b, furry F is completely dominant to hairless f

3. Black displays incomplete dominance to albino , and furry is codominant with hairless

4. Animals that are heterozygous at either locus are black and furry, overriding the other locus' geneotype

5. The black allele B displays epistasis when present at even one copy that masks the effects of the hairless f allele

6. It takes two black B alleles to mask the effects of the hairless f allele

7. Both the black alleles B and furry alleles F are lethal in their homozygous dominant states

8. Both the albino alleles b and hairless alleles f are lethal in their homozygous recessive states

9. Female dogs die when they have homozygous recessive or homozygous dominant states for either locus (dogs use XY inheritance for sex like we do). Note sex of doss in your phenotype ratios.

10. The black allele B although completely dominant, is the only 70% penetrant in heterozygotes and is 90% penetrant in homozygotes for the B allele

11. The hairless allele f is dominant in males and recessive in females

PCB 3063 Lecture Notes - Lecture 2: Genetic Linkage, Meiosis, Chromosome

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