Principles of Inheritance Exercise

Principles of Inheritance Exercise - widow’s peak What...

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Principles of Inheritance Exercise As explained in lecture, organisms inherit one copy of every gene from each parent. These heritable traits, called alleles come in two forms: dominant and recessive. If an organism has one copy of the dominant form of a gene from one parent and a recessive from the other parent, then the dominant gene is expressed in the individuals phenotype. For example, if a person has a copy of the dominant gene for brown eyes(B) and the recessive for blue eyes (b), that person would have brown eyes. This individual is said to be heterozygous (Bb) for the eye color trait. A homozygous individual would either have two copies of the dominant allele (BB) or two copies of the recessive allele(bb). Sample problem: What are the possible outcomes if a person who is heterozygous for the widow’s peak trait reproduces with an individual who is also heterozygous for the trait? A = no widow’s peak, a =
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Unformatted text preview: widow’s peak. What are the resulting genotypic and phenotypic ratios? Punnett Square A a A AA Aa a Aa aa The resulting phenotypic ratio for No Widow’s Peak: Widow’s Peak is 3:1. The genotypic ratio (Dominant: Heterozygous: Recessive) is 1:2:1. To get some practice with demonstrating inheritance, use the following scenarios. You should model your work and answers according to the format of the sample problem. 1) A giraffe with a long neck breeds with another that is homozygous with a short neck. N= short neck, n= long neck 2) An individual with blue eyes (b) reproduces with another individual with blue eyes. B = brown eyes, b = blue eyes 3) An individual who is homozygous for the sickle cell trait (s) has children with an individual who is heterozygous. No sickle cell = S, sickle cell =s...
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