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102 Lecture Notes - Antirrhinum Majus

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2 Dec 2022

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Incomplete dominance and codominance are both types of inheritance where one allele (a form of a gene) isn"t completely dominant over the other allele. This results in a new phenotype (the physical characteristics of an individual). The process in which two true-breeding parents crossed to produce an intermediate offspring is called incomplete dominance. Incomplete dominance is referred to as partial dominance or intermediate inheritance. Incomplete dominance is when there is a blending of the two alleles that results in a third phenotype that doesn"t look like either of the parents . Incomplete dominance occurs because neither of the 2 alleles is totally dominant over the opposite. This results in a phenotype that is a combination of both. Codominance refers to the phenomenon in which dominance of the two alleles or traits of the genotypes is expressed together in offspring. In codominance, there is neither a dominant nor recessive allele in cross-breeding.

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Related Questions

You are an ecologist studying a population ofgerbils that can be found in nature with 3 different colors. Anindividual gerbil can be, dark brown, medium brown, or lightbrown. There are 2 alleles for this gene B and b. Thecolor trait is determined by incomplete dominance. This is a casewhere one allele is not dominant over the other but insteadheterozygous individuals show an intermediate phenotype. In thiscase of incomplete dominance Dark brown individuals are homozygousBB, medium brown individuals are heterozygous Bb, and light brownindividuals are homozygous bb. You spend a night trapping andcatch.

10 Dark brown gerbils
10 Medium brown gerbils
10 Light brown gerbils

What is the gene pool in thispopulation?
What is the gene frequency in thispopulation?

Explain how genetic drift could alter thegene frequency in a population. Use your data from the geneticdrift experiment to support your answer.

lavendercockroach31

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.

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

multiple alleles

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

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

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?

Chestnut x Cream

Palomino x Cream

Palomino x Chestnut

Palomino x Palomino

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

multiple alleles

polygenic inheritance

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

multiple alleles

polygenic inheritance

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

Recessive allele

Allosteric allele

Dominant allele

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.

Incomplete dominance

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?

polygenic inheritance

multiple alleles

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These all relate to exceptions to the inheritance patterns encountered by Mendel.â

Why do multiple and lethal alleles often result in modifications of the classic Mendelian monohybrid and dihybrid ratios?

Select the four correct statements.

-When an essential gene is mutated, it can result in a lethal phenotype. There are no classic Mendelian monohybrid and dihybrid ratios.

-In the case of codominance, heterozygotes produce gene products from both alleles of a gene. Classic Mendelian monohybrid and dihybrid ratios are modified by codominance.

-In the case of incomplete dominance, the phenotype of the heterozygote is distinct from and often intermediate to the phenotypes of homozygous individuals. Classic Mendelian monohybrid and dihybrid ratios are modified by incomplete dominance.

-Genes exist in a large number of allelic versions and a diploid organism has two homologous gene loci that may be occupied by different alleles of the same gene. This can result in many different phenotypes for traits, which may not follow typical Mendelian ratios.

-When an essential gene is mutated, it can result in a lethal phenotype. This results in a modification of classic Mendelian ratios.

-The phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes. The joint expression of both alleles in a heterozygote is called codominance. There are no classic Mendelian monohybrid and dihybrid ratios.

-Genes exist in a large number of allelic versions, but in a diploid organism, only one allele of the gene can occupy one homologous gene loci. Classic Mendelian inheritance cannot explain this phenomenon.

-Each gene produces a unique gene product. The effect of one allele in a heterozygote completely masks the effect of the other. Classic Mendelian genetics cannot explain this phenomenon.