Pedigrees 1. Hand in your Baby Lab packet. KEEP the sheet with all the chromosomes. 2. Get tape and post your baby picture in the hallway with the others. 3. Pick up a handout.

Homework Pedigree worksheet due Wednesday Pedigree Poster Project due Monday 3/29

Objectives Be able to interpret a pedigree Be able to draw a pedigree

Pedigrees We know how to use Punnett Squares to figure out offspring, and their parents. We can apply this principle to figure out whole families… A pedigree is a family tree showing the transmission of traits. Today, I’ll give you instructions on how to read and make a pedigree. But no standard underlined notes, you must write instructions and examples for yourself in a way that you will be able to refer to later.

Pedigrees = female = male = a “blood relationship” (biological parent & child) We don’t draw lines to connect siblings to each other, just parents = an important “non-blood relationship,” like a romantic relationship, marriage, or adoption Here’s a part of my family tree as an example. Explain what’s going on:

P F1 F2

Pedigrees Making the family tree itself is relatively easy, no matter what kinds of circumstances the family has seen. But in genetics, the point of doing this is to be able to see where an allele came from and who might also be carrying it. We shade in peoples’ circles/squares to show their phenotype, and write their genotype next to them. A shaded circle/square = a person with the recessive phenotype. In my family, the recessive phenotype of blue eyes would be represented like this:

P F1 F2 ??

Pedigrees Since blue eyes is the recessive phenotype, that means we also know all the shaded peoples’ genotypes. (If we’re using the letter B/b for eye color, what would that blue eyes genotype be?)

P F1 F2 ?? bb B_ _ B_ _ B_

Pedigrees And for those family members with the dominant phenotype, can we determine the second allele of their genotypes? How?

P F1 F2 ?? bb B_ _ B_ _ B_

P F1 F2 ?? bb Bb B__ B_ _ Bb

Pedigrees Lastly, for those two people whose phenotypes are entirely unknown, can we figure out any part of their genotypes at all?

P F1 F2 ?? bb Bb B__ B_ _ Bb

P F1 F2 ?? bb Bb B??b B? Bb

Pedigrees There are four alleles that we cannot know for sure. On some family trees, we can predict the likelihood that they would be dominant or recessive. On this tree, it happens to be 50/50 every time.

P F1 F2 ?? bb Bb B??b B? Bb

Pedigrees Pedigrees can not only be used to determine information about a family’s genotypes, but this tool can also be used to determine the nature of the allele itself. Suppose a disease is found to be heritable. From the pedigree, we could figure out whether the disease allele is dominant or recessive. Shaded individuals have the new condition.

1.Try filling in the tree for a disease caused by a dominant allele. 2.Then try filling it in for a recessive allele. Decide which makes more sense.

Now try this one. Is the disease (shaded) dominant or recessive?

Family Pedigree Your Family Pedigree project requires you to: 1. Choose a trait to track through your family. 2. Choose family members (blood relations or otherwise) to study. Try not to skip generations if possible. For instance, if you have an uncle you don’t want to include, that’s no problem but don’t include his wife or children either. It’s fine to have a person with an unknown phenotype, but weird to have a blank space where a person clearly should be. 3. Contact them to find out what their phenotype is. 4. Create a poster showing your complete pedigree, including Punnett Squares for every time you had to figure out the genotype of a person with a dominant phenotype.

Pedigrees For now: First, read the project description. If you have any questions, now is a good time to ask me. Then, begin work on your pedigree practice worksheet. With respect to the project, if you ever have a family situation you’re not sure how to handle or represent on your pedigree, feel free to come check in with me now or after school.