BIOL 304 Lecture Notes - Lecture 5: Rh Blood Group System, Sickle-Cell Disease, Zygosity

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carminearmadillo571

17 Nov 2017

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Incomplete dominance & codominance: some alleles are neither dominant or recessive, many traits are controlled by multiple alleles or multiple genes. Incomplete dominance when one allele is not completely dominant over another: both alleles are partially dominant. If the genotype is heterozygous, the phenotypes become a blend : ex: red + white = pink, examples of genotype possibilities rr (red), ww (white), and it produces rw (pink) Co-dominance: co-dominance when both alleles are equally dominant and are expressed at the same time. Inheritance of blood type: co-dominance occurs when both alleles are fully dominant, the result of this is both alleles being expressed and two distinct phenotypes being observed. Human blood types: a, b, ab, o. Ib type b i type o (recessive) Possible genotypes: type a ia ia(homozygous), ia i (heterozygous, type b ib ib (homozygous), ib i (heterozygous, type ab ia ib (codominance, type o ii.

Related Questions

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

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.

Q 1 â Manx cats are produced when a dominant allele is inherited for the Manx gene (M). Inheritance of two dominant alleles, however, results in death of the fetus. Coat color in cats is determined by two alleles with incomplete dominance. BB produces black colored cats, Bb produces grey cats, and bb produces white cats. A grey Manx cat is mated with a white Manx. What proportion of the living offspring will be white Manx kittens? (3 points)

Q 2 â In goats, a beard is produced by an autosomal allele that is dominant in males and recessive in females. Weâll use the symbol B^b for the beard allele and B+ for the beardless allele. Another independently assorting autosomal allele that produces a black coat (W) is dominant over the allele for white coat (w). Give the phenotypes and their proportions expected for the following cross: B⁺B⁺Ww male Ã B^bB^bWw female (2 points)

Q 3 â E. W. Lindstrom crossed two corn plants with green seedlings and obtained the following progeny: 3583 green seedlings, 853 virescent-white seedlings, and 260 yellow seedlings.

Give the genotypes for the green, virescent-white, and yellow seedlings

Explain how color is determined in these seedlings (which genotype gives which phenotype). (3 points)

Q 4 â You are studying a gene that controls ossicone (horn) length in giraffes. The wild-type long-ossicone allele (L) is dominant to the mutant short-ossicone (l) allele. However the L allele is only 60% penetrant in both homozygotes and heterozygotes. In a population of 212 giraffes in an African nature preserve, 80 giraffes are either homozygous or heterozygous for the long ossicone allele (L). What proportion of offspring would you expect to exhibit the long ossicone phenotype? (2 points)

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BIOL 304 Lecture Notes - Lecture 5: Rh Blood Group System, Sickle-Cell Disease, Zygosity

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