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Mendel’s Punnett Squares. Genes and Alleles Gene: Place on chromosome and determines certain trait Allele: variation of that trait Ex: Gene: Eye color.

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Presentation on theme: "Mendel’s Punnett Squares. Genes and Alleles Gene: Place on chromosome and determines certain trait Allele: variation of that trait Ex: Gene: Eye color."— Presentation transcript:

1 Mendel’s Punnett Squares

2 Genes and Alleles Gene: Place on chromosome and determines certain trait Allele: variation of that trait Ex: Gene: Eye color Located on 5 th gene from the top Alleles: Brown, Blue, Green, Gray

3 Mendelian Traits Each trait 1 gene with 2 variations or 2 alleles For each allele, 1 is Dominant 1 is Recessive Dominant has a capital letter while recessive has lower case letter A genotype= is the actual allele combination (Aa, AA, aa) A phenotype= is what trait that expresses (Tall or Short)

4 Types of genotypes and phenotypes If an individual is purebred=homozygous If an individual is homozygous dominant= AA If an individual is homozygous recessive= aa If an individual is heterozygous= Aa Phenotypes – Homo Dom. and Heterozygous expresses dom allele – Homo Rec. expresses recessive allele

5 Genotypes and Phenotypes Example Eye color – The allele for blue eye color is ‘b’ – The allele for brown eye color is ‘B’ 1.What is the phenotype of picture A? What is it’s genotype? 2.What is the phenetype of picture B? What is its genotype? A B

6 Getting a phenotype from a Genotype Eye color – The allele for blue eye color is ‘b’ – The allele for brown eye color is ‘B’ 1.What is phenotype of Bb? 2.What is the phenotype of bb? 3.What is the phenotype of BB?

7 Predicting ratios This is where you are given two individuals an pretending they are making a child, but before they make the child they want to the probability of getting a particular trait Scenario Blue eyed and Brown eyes person with genotypes of ‘bb’ and ‘BB’ What are the ratios of the genotypes: BB- Bb- bb- What are the ratios of phenotypes: Blue eyes- Brown eyes-

8 3 Possible Monohybrid Crosses Type 1 AA x aa Phenotype ratios: Genotype ratios

9 3 Possible Monohybrid Crosses Type 2 AA x Aa Phenotype ratios: Genotype ratios

10 3 Possible Monohybrid Crosses Type 3 Aa x Aa Phenotype ratios: Genotype ratios

11 3 Possible Monohybrid Crosses Type 4 Aa x aa Phenotype ratios: Genotype ratios

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