Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
PEDIGREE ANALYSIS INTRODUCTION Traits in humans are often difficult to study for several reasons. Unlike Drosophila, which produce large numbers of offspring very quickly, humans reproduce slowly and produce few offspring at one time. So traits in humans must be studied through pedigree analysis. PROCEDURE Part A The Basics 1. The diagram below shows a pedigree. A pedigree shows a family’s pattern of inheritance for a specific trait. 2. In a pedigree, each person has a number and each generation is represented by a Roman numeral. In this way, each individual is identified by a Roman and an Arabic numeral. Females are represented by circles and males by squares. Shaded symbols indicate individuals homozygous recessive for the trait. 3. The trait shown in the pedigree is the ability to taste PTC paper. The dominant taster trait is represented by “T.” 4. What is the genotype of person I-2? _____________ Explain. ________________ _____________________________________________________________________ 5. What is the genotype of persons II-1, II-2, II-3, and II-4? ____________ Explain. _____________________________________________________________________ 6. What are the two possible genotypes for person II-6? _________________________ Explain. _____________________________________________________________ 1 1 2 2 3 I 4 5 6 1 II III Part B Numbering and Labeling 1. Write the Roman numeral for each generation. 2. Write the Arabic number for each individual. 3. Assume the shaded symbols represent the genotype “rr.” Write the genotype below each arabic number. Roman numeral Arabic number _____ _____ genotype _____ _____ _____ Arabic number _____ _____ _____ _____ _____ _____ genotype _____ _____ _____ _____ _____ _____ Arabic number _____ _____ _____ genotype _____ _____ _____ _____ _____ Part C The Trait of Albinism 1. Write the Roman numeral for each generation. 2. Write the Arabic number for each individual. 3. Assume individuals I-1 and I-2 are homozygous for normal pigmentation. Let “A” represent the dominant gene. 4. Write the genotype below each arabic number. Roman numeral Arabic number ____ ____ ____ ____ ____ ____ ____ ____ genotype ____ ____ ____ ____ ____ ____ ____ ____ Arabic number ____ ____ ____ ____ ____ ____ ____ ____ genotype ____ ____ ____ ____ ____ ____ ____ ____ Arabic number ____ ____ ____ ____ genotype ____ ____ ____ ____ ____ ____ ____ Part D The Trait of Night Blindness 1. Fill in the Roman numerals and Arabic numbers for the pedigree. 2. Let “N” represent the dominant gene for normal vision. Let “n” represent the recessive gene for night blindness. 3. Assume that night blindness is a sex-linked trait. Therefore you will need to write the X and Y chromosomes and use superscripts for the genes. (i.e. XnY) 4. Note that individuals I-8, II-5 and III-3 are homozygous. Individuals I-4 and III-2 are heterozygous. Roman numeral Arabic number ____ ____ ____ ____ ____ ____ ____ ____ genotype ____ ____ ____ ____ ____ ____ ____ ____ Arabic number ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ genotype ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ ___ Arabic number ___ ___ ___ ___ ___ ___ genotype ___ ___ ___ ___ ___ ___ Arabic number genotype ___ ___ ___ ___ ____ ____ ____ ____