Survey
* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project
Download Name________________________________________
Document related concepts
no text concepts found
Transcript
Name________________________________________ Date_______ Model 7: Polygenic Inheritance Exercise 10 Differences in skin color are largely due to differences in the amount of melanin, a dark pigment produced by skin cells. At least three genes control the synthesis of melanin. Each gene has two forms: an allele for high melanin production, or dark skin (A,B,C), and an allele for low melanin production, or light skin (a,b,c). Each dark skin allele (A,B,C) in the genotype adds a small but equal amount of pigment to the skin. There are seven different shades of skin color ranging from very dark (AABBCC) to very light (aabbcc). Most individuals produce a medium amount of melanin and are of intermediate skin color (AaBbCc). The following Punnett square shows the possible offspring from a cross between two individuals of intermediate skin color. AaBbCc X AaBbCc Gametes ABC ABc AbC Abc aBC aBc abC abc ABC ABc AbC Abc aBC aBc abC abc AABBCC AABBCc AABbCC AABbCc AaBBCC AaBBCc AaBbCC AaBbCc AABBCc AABBcc AABbCc AABbcc AaBBCc AaBBcc AaBbCc AaBbcc AABbCC AABbCc AAbbCC AAbbCc AaBbCC AaBbCc AabbCC AabbCc AABbCc AABbcc AAbbCc AAbbcc AaBbCc AaBbcc AabbCc Aabbcc AaBBCC AaBBCc AaBbCC AaBbCc aaBBCC aaBBCc aaBbCC aaBbCc AaBBCc AaBBcc AaBbCc AaBbcc aaBBCc aaBBcc aaBbCc aaBbcc AaBbCC AaBbCc AabbCC AabbCc aaBbCC aaBbCc aabbCC aabbCc AaBbCc AaBbcc AabbCc Aabbcc aaBbCc aaBbcc aabbCc aabbcc The offspring of this cross exhibit seven shades of skin color based on the number of dark skin alleles in each genotype. ©Modeling Instruction Program 1 Model 7 - Heredity Name________________________________________ Date_______ Model 7: Polygenic Inheritance Exercise 10 Fill in the information in the following chart to determine the probability that the children might have a different skin color than the parents. Example: Count the number of boxes with 3 dominant alleles, write it in the correct column and then divide that number by 64 to get your % probability. Round the % to the nearest hundredth (.01) place. Skin color 3 shades darker 2 shades darker 1 shade darker Same as parents 1 shade lighter 2 shades lighter 3 shades lighter # of dark alleles # of times that sequence appears in punnett square Probability (%) 6 5 4 3 2 1 0 Questions 1. Each parent produces eight different types of gametes, which can combine in 64 different ways. Complete the following table: 2. How many of these 64 possible offspring have skin that is darker than their parents? ____ 3. Each of these three genes has two alleles. Are the dark skin alleles dominant to the light skin alleles? _____________________________________________________________ 4. There are more than 7 shades of skin color. Offer an explanation. ________________________________________________________________ Copyright © 2008 by the National Center for Case Study Teaching in Science. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work. ©Modeling Instruction Program 2 Model 7 - Heredity
Related documents