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GENETIC PRINCIPLES. Lounging around the house Two heads are better than one Look before you leap.

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Presentation on theme: "GENETIC PRINCIPLES. Lounging around the house Two heads are better than one Look before you leap."— Presentation transcript:

1 GENETIC PRINCIPLES

2 Lounging around the house Two heads are better than one Look before you leap

3 GENETIC PRINCIPLES If the genes are on the same chromosome, they will not follow the law of Independent Assortment. Polygenic Inheritance: When more than one gene affects the phenotype of a trait. Target: I will be able to identify the phenotype given a genotype in incomplete dominance, co-dominance, and multiple alleles. Pg. 33

4 Exceptions to Simple Dominance: 1. Incomplete Dominance: when the two alleles in a heterozygous genotype contribute to the individual phenotype that isn’t like either parent  Neither allele is completely dominant; there is a blend of the two. R WWWW RW Genotype Ratio: 4 (100%) RW Phenotype Ratio: 4 (100%) Pink

5 2. Co-Dominance: When two dominant alleles are expressed at the same time  Represented in Punnett squares by capital letters with superscripts- ex: C B, C W. C B CWCWCWCW C B C W Genotype Ratio: 4 (100%) C B C W Phenotype Ratio: 4 (100%) black and white (C B, C W ) C B C W

6 3. Multiple Alleles: When there are more than two alleles for a trait Ex: There are three types of blood alleles in humans- A, B, and O  A and B are Dominant over O  O is Recessive  A and B are Co-Dominant CaucasiansAfrican American HispanicAsian O +37%47%53%39% O -8%4% 1% A +33%24%29%27% A -7%2% 0.5% B +9%18%9%25% B -2%1% 0.4% AB + 3%4%2%7% AB -1%0.3%0.2%0.1%

7 Human Blood Types Summary: GenotypeBlood Type (Phenotype) A I B I B or I B i B iiO I A I B AB I A i IA IBIA IB I A I A or I A i I A I A i I A I B I B i Genotype Ratio: 1 I A I A : 1I A i : I A I B : I B I Phenotype Ratio: 2 Type A: 1 Type AB: 1 Type B

8 WHEN MENDEL WAS WRONG Divide paper into 3 sections. Draw pictures to represent Incomplete Dominance, Co-Dominance, and Multiple Alleles *Use a minimum of 4 colors Pg. 32


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