Pedigrees What is a pedigree Pedigree Copyright 2008

Pedigrees!

What is a pedigree? • Pedigree - Copyright © 2008 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Fig. 14 -15 a Basic Pedigree Symbols Male Affected male Female Affected female Mating Offspring, in birth order (first-born on left)

Fig. 14 -15 b 1 st generation (grandparents) 2 nd generation (parents, aunts, and uncles) Ww ww ww Ww Ww Ww ww 3 rd generation (two sisters) WW or Ww Widow’s peak ww No widow’s peak (a) Is a widow’s peak a dominant or recessive trait?

The Behavior of Dominant Alleles Copyright © 2008 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Fig. 14 -15 c 1 st generation (grandparents) Ff 2 nd generation (parents, aunts, and uncles) FF or Ff ff ff Ff Ff Ff ff ff FF or Ff 3 rd generation (two sisters) Attached earlobe Free earlobe (b) Is an attached earlobe a dominant or recessive trait?

The Behavior of Recessive Alleles Copyright © 2008 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

General Strategies… • Determine if the trait is dominant or recesive • Identify the homozygous recessives! • Work backwards, remembering one allele must always come from each parent! Copyright © 2008 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

I. III. IV.

General Strategies… • Determine if the trait is dominant or recessive • Identify the homozygous recessives! • Work backwards, remembering one allele must always come from each parent! Copyright © 2008 Pearson Education Inc. , publishing as Pearson Benjamin Cummings

Combining Pedigrees + Punnett Squares Individual IV-1 marries a woman who is not albino, but who has a child from a previous marriage with albinism. What is the probability their first child will be albino? Copyright © 2008 Pearson Education Inc. , publishing as Pearson Benjamin Cummings