Unit 6 Lesson 5 Punnett Squares and Pedigrees Copyright © Houghton Mifflin Harcourt Publishing Company 1

Unit 6 Lesson 5 Punnett Squares and Pedigrees Florida Benchmarks SC.7.L.16.2 Determine the probabilities for genotype and phenotype combinations using Punnett Squares and pedigrees. MA.6.A.3.6 Construct and analyze tables, graphs, and equations to describe linear functions and other simple relations using both common language and algebraic notation. Copyright © Houghton Mifflin Harcourt Publishing Company 2

Unit 6 Lesson 5 Punnett Squares and Pedigrees Florida Benchmarks LA.6.4.2.2 The student will record information (e.g., observations, notes, lists, charts, legends) related to a topic, including visual aids to organize and record information and include a list of sources used. HE.6.C.1.4 Recognize how heredity can affect personal health. Copyright © Houghton Mifflin Harcourt Publishing Company 3

Unit 6 Lesson 5 Punnett Squares and Pedigrees Squared Away How are Punnett squares used to predict patterns of heredity? One tool for understanding the patterns of heredity is a diagram called a Punnett square. A Punnett square is a graphic used to predict the possible genotypes of offspring in a given cross. Copyright © Houghton Mifflin Harcourt Publishing Company 4

How are Punnett squares used to predict patterns of heredity? Unit 6 Lesson 5 Punnett Squares and Pedigrees How are Punnett squares used to predict patterns of heredity? Each parent has two alleles for a particular gene. An offspring receives one allele from each parent. Each compartment within the Punnett square shows an allele combination in a potential offspring. Copyright © Houghton Mifflin Harcourt Publishing Company 5

How can a Punnett square be used to make predictions about offspring? Unit 6 Lesson 5 Punnett Squares and Pedigrees How can a Punnett square be used to make predictions about offspring? A Punnett square does not tell you what the exact results of a cross will be. A Punnett square only helps you find the probability that a certain genotype will occur. Probability is the mathematical chance of a specific outcome in relation to the total number of possible outcomes. Copyright © Houghton Mifflin Harcourt Publishing Company 6

How can a Punnett square be used to make predictions about offspring? Unit 6 Lesson 5 Punnett Squares and Pedigrees How can a Punnett square be used to make predictions about offspring? Probability can be expressed in the form of a ratio, or an expression that compares two quantities. Probability can also be expressed as a percentage. A percentage states the number of times a certain outcome might happen out of 100 chances. Copyright © Houghton Mifflin Harcourt Publishing Company 7

How can a pedigree trace a trait through generations? Unit 6 Lesson 5 Punnett Squares and Pedigrees How can a pedigree trace a trait through generations? A pedigree is another tool used to study patterns of inheritance. A pedigree traces the occurrence of a trait through generations of a family. Pedigrees can be useful in tracing sex-linked disorders, or disorders associated with an allele on a sex chromosome. Copyright © Houghton Mifflin Harcourt Publishing Company 8

How can a pedigree trace a trait through generations? Unit 6 Lesson 5 Punnett Squares and Pedigrees How can a pedigree trace a trait through generations? A woman that is heterozygous for a trait is called a carrier. She is called a carrier because she can pass the trait to her offspring. Copyright © Houghton Mifflin Harcourt Publishing Company 9

How can a pedigree trace a trait through generations? Unit 6 Lesson 5 Punnett Squares and Pedigrees How can a pedigree trace a trait through generations? Pedigrees can be useful in tracing inherited disorders such as cystic fibrosis. Copyright © Houghton Mifflin Harcourt Publishing Company 10

Saving the European Mouflon Unit 6 Lesson 5 Punnett Squares and Pedigrees Saving the European Mouflon Scientists use genetics to show how the European mouflon sheep can be saved from extinction. When a population is very small, there is a risk of too much interbreeding, which can cause harmful genetic conditions to appear. Researchers can identify and breed genetically dissimilar European mouflons in a laboratory. This lowers the risk of inherited disorders. Copyright © Houghton Mifflin Harcourt Publishing Company 11