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Section 7-2 “Complex Inheritance”

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1 Section 7-2 “Complex Inheritance”
Write everything that is BLACK

2 KEY CONCEPT Phenotype is affected by many different factors

3 Phenotype can depend on interactions of alleles
Incomplete dominance: neither allele is completely dominant nor completely recessive Heterozygous phenotype is intermediate between the two homozygous phenotypes

4 Codominant alleles will both be completely expressed
Codominant alleles are neither dominant nor recessive The ABO blood types result from codominant alleles Many genes have more than two alleles

5 How can two people with type B blood have a child with type O blood?
If two people are heterozygotes (IBi) they can each pass the recessive allele (i) to their offspring.

6 Many genes may interact to produce one trait
Polygenic traits are produced by two or more genes Order of dominance: brown > green > blue.

7 An epistatic gene can interfere with other genes
An epistatic gene blocks the production of pigments.

8 How do multiple allele traits differ from polygenic traits?
Multiple allele traits are influenced by several different versions of one gene; polygenic traits are influenced by multiple genes

9 The environment interacts with genotype
Phenotype is a combination of genotype and environment The sex of sea turtles depends on both genes and the environment Height is an example of a phenotype strongly affected by the environment Warm = female Cold = Male

10 Sunlight can cause a person’s hair to become lighter in color
Sunlight can cause a person’s hair to become lighter in color. Is this an example of an interaction between genes and the environment? Why or why not? Yes, because the phenotype is altered by the environment.

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