GeneticsTuesday1/19/2016

Agenda: Pedigrees

Notes: Pedigrees Activity: Pedigree Worksheet Activity: Genetics Review Guide GENETICS EXAM WEDNESDAY/THURSDAY 1/20-1/21/2016

Homework/Class Work:Pedigree Worksheet and Review Guide due Wednesday/Thursday 1/20-1/21/2016 for 30 Points

Understanding a Pedigree

ChartA family history of a genetic condition

Genotypes and Phenotypes

• Mom and Dad are Rr-that is their genotype, they can also be described as heterozygous- they have 1 of each gene

• What is their PHENOTYPE?

• The youngest son has a genotype of rr-he is Homozygous recessive-2 copies of the recessive gene

• His phenotype?

I can’t Roll my Tongue!

Some common dominant and recessive traits• Widow’s peak is dominant. • You can be homozygous

dominant (WW) or heterozygous (Ww) and you will have widow’s peak• What is your genotype and

phenotype if you’re homozygous recessive?

Making a Pedigree Chart• Pedigree charts are

made to chart family history and see how traits are passed

• A genetic counsellor will use pedigree charts to help determine the distribution of a disease in an affected family

Symbols• Shade individuals that

have the trait you’re studying

• Boys = squares (Lucy always calls Charlie Brown a ‘block head’)

• Girls = circles

Draw me

• Married-connected at side• Siblings-connected at TOP not at the side (hopefully not siblings AND married)• Oldest child-to the left• Question-if shaded

individuals in this pedigree have blue eyes, what is the GENOTYPE of the parents?

Making a Pedigree Chart

Other• Divorced, separated• Deceased• Identical twins• Fraternal twins

Generations are identified by Roman numerals

Organizing the pedigree chart

I

II

III

IV

Organizing the pedigree chart• Individuals in each generation are identified by Arabic

numerals numbered from the left• Therefore the affected individuals are II3, IV2 and IV3

I

II

III

IV

1 2 3 4 5 6 7

What’s going on?Shaded = blue eyes

• 1 and 2 split after having 4, 2 then had kids with 3 and split with her too after 5-9 were born

• Genotypes of 1, 4,7? • Genotypes of 2 & 3?• Genotypes of 5,6, 8, 9, 10,

11, 12?