Week 10 Notes - BIOL1103 Notes for Monday, March 29th In...

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BIOL1103 Notes for Monday, March 29 th In the figure above traits are passed in the gametes: Pollen (sperm) and eggs. One allele comes from the pollen and one from the egg. The offspring are 3/4ths tall (TT, Tt, tT) and 1/4 th short Homozygous dominant: two copies of the same dominant allele (TT) Homozygous recessive: two copies of the same recessive allele (tt) Heterozygous: two different copies of an allele, one dominant and one recessive (Tt) Monohybrid crosses involve following 1 trait Dihybrid crosses involve following 2 traits Phenotype (visible characteristics) Genotype (genetic characteristics) Particulate theory of inheritance: 2 particles (factors) determine a trait ; blending hypothesis is wrong! Dihybrid Crosses (=Breeding experiments involving two traits) Seed shape = Round (R) or wrinkled (r) seeds Seed color = Yellow (Y) or green (y) seeds RRYY x rryy = RrYy (this is the F1 generation) RrYy is the genotype, and round yellow is the phenotype.
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Note that in the dihybrid cross above there is a 9:3:3:1 ratio! Mendel characterized his results from the dihybrid cross with the term independent assortment because the alleles for the two traits are not connected to each other when they are passed from parents to offspring. Mendel is credited with three major ideas: 1) The Particle Theory of Inheritance — states that hereditary traits act like particles, units, or factors as they are passed from generation to generation 2) His Law of Segregation –which states that his hereditary factors do not blend but remain distinct during breeding—thus, disproving the blending theory. 3) His Law of Independent Assortment –which states that character traits are not connected but are inherited independent of one another. (This law was to be soon to be modified)
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Notes from Wednesday 3-31-10 Mendel picked simple traits to study o He picked traits controlled by a single gene with two alleles Clear Dominance: One allele is dominant to the other Examples: tall vs. short and white or red Incomplete Dominance o The second allele in a organism doesn’t produce a functioning enzyme It is heterozygous For example white and red are crossed to produce some pink Blood groups I^A has type A sugar I^B has a different sugar called type B i. has no sugar o The body looks to see which sugars are present o If it is the wrong sugar then the body will reject it o If there is no sugar (i.e. i.)then the body will be ok o
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Blood Type Genotype A I^A I^A or I^A i. B I^B I^Bor I^B i. AB I^A I^B type AB is co-dominance not incomplete O i. i. Polygenic inheritance o More than one gene o Displayed by a bell curve o It is a single trait controlled by multiple genes. o
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This note was uploaded on 03/23/2011 for the course BIOLOGY 1103 taught by Professor Barstow during the Spring '09 term at University of Georgia Athens.

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Week 10 Notes - BIOL1103 Notes for Monday, March 29th In...

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