Download Bio102: Introduction to Cell Biology and Genetics

Bio102: Introduction to Cell Biology and Genetics
Mendelian Genetics – Beyond Pea Plants
Key Terms:
Pedigree
Carrier
Key Questions:
 What does an allele that causes a recessive human genetic disorder usually do? (What do we
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suspect is true about the protein it encodes?)
Why are fewer lethal human genetic diseases caused by dominant alleles than by recessive
alleles?
If we determine that a particular trait is recessive by looking at a pedigree, what do we
automatically knowabout the genotypes of the individuals in the pedigree?
If we determine that a particular trait is dominant by looking at a pedigree, what do we
automatically know about the genotypes of the individuals in the pedigree?
How can a pedigree be useful in counselling prospective parents who are concerned about their
children inheriting genetic disorders that run in the family? Why is pedigree-based
information sometimes incomplete?
In analyzing a pedigree, why is it useful to know whether a trait is common or rare in the
population?
Lecture Outline:
Human genetics offers unique challenges and opportunities
no controlled matings, few offspring, long generation times, no true-breeding
collected histories
Pedigrees
circles for females, squares for males
filled symbol is affected (often means diseased)
affected child of unaffected parents is strong evidence for recessive trait
recessive traits are not always rare