Do now activity #2 Write down an example of homozygous dominant allele pairs. Write down an example of homozygous recessive allele pairs. Write down an example of heterozygous allele pairs. Described the relationship shared between the genotype and the phenotype.

Essential Question: Section 4-2: alleles How does the genotype of an organism determine the phenotype of that organism? Learning Target Distinguish between dominant and recessive traits. Distinguish between heterozygous and homozygous genotypes. Explain how the genotype of an organism results in the phenotype of the organism. Section 4-2: alleles

announcements Section 4 Test Scheduled for this Friday: 6/15/18 Section 4 Stamp Sheet due Friday 6/15/18

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Alleles occur in pairs (2). overview Alleles occur in pairs (2).

We get one from ___ & one from ___ . overview Mom/dad We get one from ___ & one from ___ . Mom Dad

Dominant traits are written with an __________ allele. overview Uppercase letter uppercase Dominant traits are written with an __________ allele.

Recessive traits are written with a ____________ allele. overview lowercase letter Recessive traits are written with a ____________ allele. lowercase

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___________ alleles are the same. Same or different homozygous ___________ alleles are the same. Homozygous

Homozygous _______ alleles are both capitalized. Same or different dominant Homozygous _______ alleles are both capitalized. dominant

Homozygous _______ alleles are both lowercase. Same or different recessive Homozygous _______ alleles are both lowercase. recessive

___________ alleles are different. Same or different heterozygous Heterozygous ___________ alleles are different.

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What we can physically see now you see me… Phenotype What we can physically see

The genetic “code” we do not see now you don’t! Genotype The genetic “code” we do not see

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Some alleles are not as simple as either dominant or recessive Exceptions to the rule Some alleles are not as simple as either dominant or recessive

Some alleles are neither dominant nor recessive Exceptions to the rule Some alleles are neither dominant nor recessive

Many traits are controlled by multiple alleles or genes Exceptions to the rule Many traits are controlled by multiple alleles or genes

Incomplete Dominance: When one allele is not completely dominant over the other Example: RR = red flower rr = white flower Rr = pink flower The exceptions

When both alleles contribute to phenotype Codominance: When both alleles contribute to phenotype Example: RR = red flower rr = white flower Rr = red & white flower The exceptions

when more than two alleles contribute to the phenotype Multiple Alleles: when more than two alleles contribute to the phenotype Example: Blood type A Blood type B Blood type AB Blood type O The exceptions

Many traits produced by the interaction of several genes The exceptions Polygenic Traits: Many traits produced by the interaction of several genes Examples: Hair color Eye color Height