Presentation on theme: "Making a Pedigree Chart"— Presentation transcript:
1 Making a Pedigree Chart A family history of a genetic condition
2 Quick Review Genotype = what genes someone has Genes are usually represented by a letter, a capital letter for the dominant trait, a small case for the recessive.Example: Tongue Rolling is dominant, so we use R to represent the tongue rollingInablility to roll your tongue is recessive so we use r to represent the non-rolling geneFor every trait, you get a gene from each parent
3 Genotypes and Phenotypes Mom and Dad are Rr-that is their genotype, they can also be described as heterozygous-they have 1 of each geneWhat is their PHENOTYPE?The youngest son has a genotype of rr-he is Homozygous recessive-2 copies of the recessive geneHis phenotype?tongue rollersRrRrI can’tRoll myTongue!non-rollerRrrrRrRr
4 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 peakWhat is your genotype and phenotype if you’re homozygous recessive?ww, no widow's peak
5 Making a Pedigree Chart Pedigree charts are made to chart family history and see how traits are passedA genetic counsellor will use pedigree charts to help determine the distribution of a disease in an affected family
6 Symbols Shade individuals that have the trait you’re studying Boys = squares (Lucy always calls Charlie Brown a ‘block head’)Girls = circles
7 Married-connected at side Siblings-connected at TOP not at the side (hopefully not siblings AND married)Oldest child-to the leftQuestion-if shaded individuals in this pedigree have blue eyes, what is the GENOTYPE of the parents?both must be Bb
9 Organizing the pedigree chart Generations are identified by Roman numeralsIIIIIIIV
10 Organizing the pedigree chart Individuals in each generation are identified by Arabic numerals numbered from the leftTherefore the affected individuals are II3, IV2 and IV3IIIIIIIV3456721
11 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 bornGenotypes of 1, 4,7?Genotypes of 2 & 3?Genotypes of 5,6, 8, 9, 10, 11, 12?123bb61045789Bb12could be BB or Bb11In what generation are there twins?III
12 Time to practice…Complete the practice worksheet on pedigrees in class (we will review)Pedigree swap activityHomework assignment – YOUR CHOICE!
13 Make your own pedigreeUsing your own family, make your own pedigree chartMust at LEAST include grandparents, parents, & your generationPick one easy dominant or recessive trait and shade individuals that have it. You can guess who has it if you don’t know for sure. (Don’t pick a trait that EVERYONE in your family has)Label yourself, grandparents, cousins, etcPut a key on the pedigree so I know what shaded means. Ex.- shaded people have widow’s peakOR…you may create a pedigree chart for a fictional family of your choice. For example, a family in a book you read or a movie you have seen (ex: Twilight series, Harry Potter, etc)
14 Which technology was important to the development of the cell theory?