Intro to Pedigrees

Master pedigree charts: learn symbols, generations, and inheritance patterns for genetic traits.

Fill in the blanks using the drop-down word banks provided. 1. In pedigrees, circles represent females and squares represent males. A pedigree is used to show how a traitis passed through generations.2. In order to indicate partners kids together, a horizontal line is drawn to connect circles and squares. In order to indicate children, a vertical line is drawn that connects them together.3. When looking at a pedigree, if you see a half-shaded circle or square, that indicates the person is a carrier. This means that they are heterozygous. On the other hand, fully shaded circles and squares represent affected individuals. Empty circles and squares represent unaffected individuals.4. Generations on a pedigree are always represented using roman numerals. Label the generations in the pedigree. USE THE CAPITAL LETTER "i" to represent the ROMAN NUMERALS! Use no spaces. If you don't use roman numerals it is incorrect. I II III How many individuals are in the above pedigree? 9 10 6 3 How many males are affected by this gene? 2 4 3 1 How many females are affected by this gene? 2 4 6 8 How many children did the first generation have? 5 4 3 2 How many granddaughters did the first generation have? 3 1 4 2 Use the pedigree to answer the questions. How can you figure out who is a carrier for color-blindness? They have gray circles and squares What symbol represents normal vision? They have empty circles and squares What symbol represents color blindness? They have filled in circles and squares How many children did I-2 have? 4 How many grandchildren did I-2 have? 8 Are there male carriers? No Are there female carriers? Yes How are II-1 and II-3 related? They are siblings (sisters) How are III-4 and III-7 related? They are cousins How many generations are there? 3 Use the pedigree about Tay-Sachs to answer the questions. Tay-Sachs disease is a recessive genetic disorder that causes deterioration of nerve cells and mental and physical abilities that begins around 6 months of age and usually results in death by the age of 4. Tay-Sachs is usually found in French-Canadians, Cajuns, and Ashkenazi Jews. Carrier parents have a 25% chance of giving the disease to their offspring. How do we identify the affected person? They have a solid symbol How many carriers are there in this pedigree? 5 Why can carriers have healthy children? They carry 1 dominant healthy allele Why can unaffected people have healthy children? They carry 2 dominant healthy alleles Can II-3 and II-4 pass this disease on to their children? No because they are both unaffected Why doesn't II-1 have a partner or children? They died of Tay-Sachs If III-3 has children with a carrier, could their children have Tay-Sachs? Yes because they are both carriers Why can carriers have unhealthy children? They carry the recessive allele