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SC.912.L.16.2. Inheritance patterns. Autosomal vs. Sex-linked. Autosomal traits will appear in both sexes equally Sex-linked traits are usually only seen in males. Dominant vs. Recessive. If autosomal dominant, every individual with the trait will have a parent with the trait
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SC.912.L.16.2 Inheritance patterns
Autosomal vs. Sex-linked • Autosomal traits will appear in both sexes equally • Sex-linked traits are usually only seen in males
Dominant vs. Recessive • If autosomal dominant, every individual with the trait will have a parent with the trait • If recessive, an individual with the trait can have one, two, or neither parent with the trait • Most sex-linked traits are recessive
Cont. • If individuals with autosomal traits are homozygous dominant or heterozygous, their phenotype will show the dominant characteristic • If individuals are homozygous recessive, their phenotype will show the recessive characteristic
Cont. • Two people who are heterozygous carriers of a recessive mutation will not show the mutation, but they can produce children who are homozygous for the recessive allele
Polygenic • Influenced by several genes • Ex: skin color, eye color, height, hair color • Complex characters are influenced by both the environment and by genes • Skin color is determined by genes but also exposure to sunlight • Height is determined by genes but also by nutrition and disease
Multiple Alleles • Genes with 3 or more alleles • Ex: blood type – Ia, Ib, i • Codominance: both alleles are expressed in the phenotype of a heterozygote • Blood types: A, B, AB, O
Incomplete Dominance • An individual displays a trait that is intermediate between the 2 parents • 1 parent with straight hair + 1 parent with curly hair = wavy hair for the child
Questions 1. Which will appear in both sexes equally? A. Autosomal traits B. Sex-linked traits
Questions 2. Sex-linked traits are usually seen in: A. Males B. Females
Questions 3. If a trait is recessive, the individual will have _______ parent(s) with the trait. A. One B. Two C. Neither D. All of the above
Questions 4. If a person with an autosomal trait is homozygous dominant or heterozygous, his phenotype will show the _____ characteristic. A. Dominant B. Recessive
Questions 5. Two people who are heterozygous carriers of a recessive mutation cannot produce children who are homozygous for the recessive allele. A. True B. False
Questions 6. Which is not a polygenic characteristic? A. Eye color B. Height C. Gender D. Skin color
Questions 7. How is skin color a complex character? • It is determined by genes and exposure to sunlight.
Questions • Which blood type is an example of codominance? • AB
Questions • Multiple alleles are genes with ___ or more alleles. A. 2 B. 3 C. 4
Questions 10. If one of an individual’s parents has straight hair and the other has curly hair, the individual will have: A. Straight hair B. Curly hair C. Wavy hair D. None of the above