Understanding Inheritance: Punnett Squares and Pedigree Analysis

ANTH 2600 Lab 3: Inheritance 1 of 4 A. Predicting Inheritance Instructions: Work with your group. Use the information provided to complete the Punnett squares below. You are looking at the gene that codes for freckles. Freckles is a dominant trait. Use the alleles F and f . Then, answer the questions that follow. Information provided: • Timmy is homozygous dominant and Sally is heterozygous for freckles. • Timmy’s dad and mom are both heterozygous for freckles. • Timmy’s grandma is homozygous recessive and his grandpa is homozygous dominant for freckles. Answer the following questions based on the Punnett squares above. 1. Does Sally have freckles? Why/why not? 2. What is the probability that Timmy and Sally will produce a child with freckles? 3. Which individual(s) in this family is/are without freckles? How do you know?

ANTH 2600 Lab 3: Inheritance 2 of 4 4. Based on the genotypes of Timmy’s grandma and grandpa, can you tell if these are his maternal grandparents (his mom’s parents) or his paternal grandparents (his dad’s parents)? Why /why not? 5. Explain which of Mendel’s laws of inheritance are at play in the Punnett squares above. 6. Challenge: If Timmy had a biological brother, what is the probability that his brother would have freckles? How did you come to your answer? (Note: biological siblings have the same parents). 7. Challenge: If Timmy had a biological sister, what is the probability that his sister would have freckles? How did you come to your answer?

ANTH 2600 Lab 3: Inheritance 3 of 4 B. Diagraming Inheritance Part I Instructions: Below is a pedigree diagram for the “tongue rolling” trait in a family over four generations (I through IV). Assume this is a monogenic trait (i.e., simple Mendelian trait). The ability to roll the tongue is an autosomal dominant trait. Use the information in the pedigree diagram to infer the genotype (or possible genotypes) of various family members. Record your responses in the table provided. Use the R and r alleles. Family Member Genotype/Possible Genotypes A B C D E F G

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ANTH 2600 Lab 3: Inheritance 4 of 4 C. Diagraming Inheritance Part II Instructions: Look at the pedigree diagram below. Discuss the information presented in the pedigree and address the questions that follow with your group. 1. Which mode of inheritance (autosomal dominant, autosomal recessive, X-linked dominant, X-linked recessive, Y- linked) is depicted in the pedigree diagram above? Explain how you arrived at your answer. 2. What is the genotype of individual #4 in the third generation (III)? __________ 3. What is the genotype of individual #7 in the fourth generation (IV)? __________

Lab 3 (2)

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