BIOL 2500 Lecture Notes - Lecture 5: Abo Blood Group System, Wild Type, Mutation

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pucealligator102

2 Jun 2016

School

University of Manitoba

Department

Biological Sciences

Course

BIOL 2500

Professor

Roman Gietz

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Document Summary

The phrase gene interaction refers to the ways genes collaborate or interact to in uence a phenotype. There are several important types of interactions. There may be more than two alleles for a given locus within a population. Dominance of one allele over another may not be complete. Two or more genes may affect a single trait. The expression of a trait may depend on the interaction of more that one gene and/or the interaction of genes with nongenic factors. Mendel chose to examine traits with just two alternative forms. In each case one form was completely dominant over the other, such that individuals heterozygous for the two allele shows the dominant phenotype. The term dominant and recessive have a phenotypic basis. However, the dominance of one allele over another is determined by the protein product of that allele. The overall phenotype is the consequence of the activities of the protein products of the alleles of the gene.

Related Questions

Differentiate amongcomplete dominance, incomplete dominance andco-dominance.

3. Understand an allelicseries -How many possible alleles are there for any given gene? Isthere only one recessive allele for a gene? Is there only onedominant allele for a gene? Is an allele always recessive ordominant with respect to other alleles of the gene?

4. What is a lethalallele? Are lethal alleles usually dominant or recessive? Are thereany exceptions? (Hint: Huntington disease in humans). How do wemaintain stocks with lethal alleles?

5. How can you tell if anallele is lethal? If one of the parents has a lethal allele, wouldall the possible genotypes be present in the progeny? What wouldhappen to the phenotypic ratios of the progeny?

6. What ispleiotropy?

7. How can you tell if atrait is determined by more than one gene? What ratios ofphenotypes in the F2 generation would you expect if a trait isdetermined by a single gene?

8. What is epistasis? Howcan the genotype at a locus affect the phenotype determined by thegenotype at another locus? What are complementary gene action,duplicate gene action, dominant suppression, dominant epistasis,and recessive epistasis?

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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

A strong understanding of the difference between gene and allele is needed now. We covered allele interactions in the lesson before this one. Allele interactions deal with a single gene and its alleles. Alleles, versions of a gene, can interact when placed together in a heterozygote.

We are now looking at two genes and how they interact. To more easily understand how two genes interact, we will only be considering the normal alleles and null alleles of both genes. Normal alleles will be dominant, null alleles will be recessive. In addition, the two genes are UNLINKED. The various interactions are made evident in standard F2 generations: Two purebred parents are crossed, a dihybrid F1 is formed, the dihybrid F1 is selfed, and F2 generation is examined. One must remember, the progeny of dihybrid selfs are always in a fixed genotype distribution: 9 A _ B_ : 3 A _ bb : 3: aa B _ : 1 aa bb. BUT, with genes interacting the phenotypic ratios are changed.

Please focus on how genes interact. You do not need to know specific pathways or organisms.

Answer the following questions.

2. There is a hypothetical plant called rat-ear. Red and pink varieties flourish in Hawaii and Long Island, NY. All the red and pink varieties can be bred true. Surprisingly, when the Hawaiian pink is bred with the Long Island pink, all the resulting progeny are red. When these red progeny are selfed the next generation has 333 red flowered and 259 pink flowered plants. The breeders breathe a sigh of relief. What do the breeders understand about the petal pigmentation of rat-ear plants?

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BIOL 2500 Lecture Notes - Lecture 5: Abo Blood Group System, Wild Type, Mutation

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