ARCL-1006EL Lecture Notes - Lecture 3: Chin, Zygosity, Phenotype

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16 Jun 2018

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ARCL 1006

January, 17, 2018

Genetics

•Recap of Mendel’s peas experiment

•Mendel’s conclusions

•That both parents contribute “unit factors” or what we would call GENES to the off-spring

•When the genes are different only one is expressed (excluding co-dominant)

•When gametes (sex cells) are formed, paired genes separate randomly so each sex cell

receives one or the other gene with equal likelihood

•Terms

•Phenotype: the observable physical appearance of the organism

•Gene: chemical unit of heredity

•Allele: alternate forms of a gene

•Genotype: the total complement of inherited genes of an organism

•Homozygous: individual carries the same allele for a speciﬁc gene

•Heterozygous: individual carries different alleles for a speciﬁc gene

•Dominant gene: expressed allele

•Recessive gene: unexpressed allele

•Co-dominiant: both alleles expressed

•Alleles and Dominance in human blood groups

•Alleles: A, B, O

•Dominant: A & B (co-dominant)

•Recessive: O

•Phenotypes and Genotypes

•person with blood type A has what possible genotypes?

•A -> AA OR AO

•Parents with blood types A and B would have offspring that might have what blood types?

•A,B,O or AB

•Mendelian Traits

•Coded by a single gene:

•cleft chin

•cheek dimples

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Related Questions

With respect to genetics, ABO blood types are controlled by asingle gene designated I, which has three alleles. The I A allelegives blood type A, I B gives blood type B, and i gives blood typeO. The I A and I B alleles are codominant and i allele is recessiveto both the I A and I B alleles.

Aside from the I alleles, there are two other genes that whenmutated affect ABO blood type inheritance. The first mutant isrecessive to wild type and is designated x. A homozygous xxindividual is phenotypically O for blood type no matter what thegenotype is of the I gene. For example, I A /I A x/x or I B /I Bx/x individuals are O type. The second mutant, is dominant to thewild type Y allele and is designated Yd . An individual carrying aYd allele is phenotypically blood type O no matter what thegenotype is of the I gene. For example, an I A /I A Y/Yd or I B /IB Y/Yd individuals is O.

a. Propose a biochemical model that explains the O phenotype ofthe recessive homozygous xx individual? Your model should explainthe biochemical function of the X gene in a wild type individualand should explain why the x mutation is recessive

maroonlocust976

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

In need of assistance. Please help answer the following.

1) Pure-breeding yellow guinea pigs crossedwith pure-breeding white guinea pigs produce only cream-coloredoffspring. This pattern indicates incomplete dominance. Rough hairis found to be dominant to smooth hair. Give the F1 and F2genotypic and phenotypic ratios of a cross of a smooth white guineapig with a homozygous rough yellow guinea pig.

2) A breeder of cattle has a herd of white cowsand a roan bull. Hair color in this breed is controlled by anincomplete dominant gene. The two homozygous forms are either redor white, and the heterozygous is roan. Answer the followingquestions please

What color calves are expected and in whatproportion?

Outline a procedure to develop an all-redherd.

3) In horses, black coat color is influenced bythe dominant allele (B), and chestnut coat color is influenced bythe recessive allele (b). Trotting gait is due to a dominant gene(T), pacing gait to the recessive allele (t). If a homozygous blacktrotter is crossed with a chestnut pacer:

What will be the appearance of the F1 and F2generations?

Which phenotype will be the most common?

Which genotype will be the most common?

Which of the potential offspring will be certain tobreed true?

4) In garden peas, one pair of alleles controlsthe height of the plant and a second pair of alleles controlsflower color. The allele for tall (D) is dominant to the allele fordwarf (d), and the allele for purple (P) is dominant for the allelefor white (p). A tall purple crossed with a tall purple produces Â¾tall purple and Â¼ tall white. What is the genotype of the parents?

5) Three alleles control the ABO blood types.I^A and I^B are codominant genes, so thecombination of I^AI^B produces the AB bloodtype. The third allele I^ois recessive to the other twoalleles. Indicate which of these parents could produce the givenchild and submit your response to the instructor.

A X AB produce B child.

A X O produce A child.

A X B produce O child.

A X AB produce O child.

A X AB produce B child.

B X B produce O child.

AB X AB produce A child.

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ARCL-1006EL Lecture Notes - Lecture 3: Chin, Zygosity, Phenotype

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