1

A pedigree is a chart for tracing genes in a family Phenotypes are used to infer genotypes on a pedigree. Autosomal genes show different patterns on a pedigree than sex-linked genes (which we will talk about soon). Ex: 2

Creating a pedigree Okay, here are some general rules to keep in mind when creating a pedigree: 1. Circles are used to represent females 2. Squares are used to represent males 3.Circles/squares are filled in or when a certain trait or disorder is expressed. 4. Circles/squares are half shaded or dotted in the center to represent carriers (heterozygous individuals). Note: Carriers of recessive diseases/disorders are considered HEALTHY and don’t express the disease or disorder. So, often, when someone is healthy, we don’t know if they’re homozygous or heterozygous. Unless, of course, the disease/disorder is dominant. 3

Let’s try an example ( Create your pedigree on a separate sheet of paper [for practice], following these instructions; you only have to include the actual drawing) : Trace the Ramirez family history of PKU (phenylketonuria), which is a recessive genetic disorder (healthy is dominant). 1.Lets start with a key: H = Healthy h = PKU Creating a pedigree (cont.) 4

2. Manny and Rosa are married and both are healthy. So…we draw an open circle and a square connected: 5

Creating a pedigree (cont.) 3. They have 3 children. 4. Their oldest child, Jacob, has a recessive disorder called PKU. So, we draw a filled in square. 6

Creating a pedigree (cont.) 5. Their middle child Erica and their youngest Matthew are healthy. We draw an open circle and square. 6. Now, If healthy is dominant to PKU, fill in the missing genotypes. –Tip: Start with what you know. 7

Creating a pedigree (cont.) We know Jacob has PKU, so his genotype is: hh Now, work backwards for the rest… If Jacob’s genotype is hh, then he has to have gotten one of each allele from each parent. hh h h H H Since Manny and Rosa are healthy, it is safe to say they are heterozygous. 8

By finishing the punnett sqaure, we know that the other 2 children could be either homozygous dominant or heterozygous. You should have something like this… Creating a pedigree (cont.) hhHH?? h H hH Hh HH HhHh 9

The next generation Now lets add on to this… 7. Erica meets Moe in college and the two get married (add to your pedigree). 8. Erica and Moe have 2 daughters (add this to your pedigree). 9. Their youngest daughter, Jaime, shows signs of PKU, while Aimee does not (add this to the pedigree). 10. Fill in the genotypes of the four individuals…STARTING with what you know. 10

If you got this you are on the right track! Good Job! The Next Generation hhH? Key H = Healthy h = PKU Hh h H 11

More Pedigree Practice Sickle cell anemia (recessive) pedigree Use the key and fill out the pedigree (on your own paper!) Key H = Healthy h = Sickle cell anemia Hint: 3 unknown 12

hh Hh H? Hh H? Key H = Healthy h = Sickle cell anemia You should have something that looks like this… 13

Now you know how to complete autosomal recessive Punnett Squares and Pedigree Charts…Dang you are smart! Now you will enter into a new type of inheritance… Autosomal DOMINANCE Return these notes for the notes and worksheet that are at the front 14