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Pedigrees and Multiple Alleles

Pedigrees and Multiple Alleles. Pedigree. A pedigree is a diagram of one trait throughout a family. It is a type of family tree. Pedigree Continued. Circles = females Squares = Males Empty shapes = lack the trait Filled shapes = have the trait

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Pedigrees and Multiple Alleles

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  1. Pedigrees and Multiple Alleles

  2. Pedigree • A pedigree is a diagram of one trait throughout a family. • It is a type of family tree.

  3. Pedigree Continued • Circles = females • Squares = Males • Empty shapes = lack the trait • Filled shapes = have the trait • Sometimes ½ filled shapes = heterozygous (AKA carriers)

  4. Is it possible to infer from the pedigree that I-1 and I-2 are carriers of the allele? Explain. Yes I-1 and I-2 are carriers because their child II-2 has the trait.

  5. 2. What can be inferred about the genotype of II-5 based on that person’s descendants? It can be inferred that II-5 is heterozygous because he lacks the trait but his grandson has the trait

  6. 3. Is II-1 a carrier of the recessive allele? Explain. II-1 we are not sure of because they have the dominant phenotype.

  7. 4. Are II-3 and II-4 carriers of the recessive gene? Explain. It is unknown whether II-3 and II-4 are carriers because they do not have children and their parents were heterozygous.

  8. 5. Why must III-4 and III-7 be heterozygous? III-4 and III-7 must be heterozygous because they both lack the trait but have children who have the trait.

  9. Can you infer from the pedigree whether the pattern of inheritance is autosomal or sex-linked? The pedigree must be autosomal because if it were sex-linked II-2 would not be able to have the trait.

  10. Multiple Alleles • Sometimes, there are more than two kinds of alleles • Each person only gets two alleles for each gene • One from mom and one from dad, but sometimes there is not only two types that they can inherit.

  11. Example of Multiple Alleles • Best example of multiple alleles: blood type • There are three types of alleles for blood type: • A; B; O • A and B are CODOMINANT • A and B are both DOMINANT over O

  12. PHENOTYPE: Type A Type B Type AB Type O GENOTYPE: IAIA or IAi IBIB or IBi IAIB ii They are represented: IA, IB, i

  13. Example: Cross a Homozygous A with an AB blood type IA IA IA IAIA IAIA IB IAIB IAIB Phenotype: 50% Type A blood and 50% Type AB blood

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