Transcript Slide 1
LH. Biology Heredity Benchmark 1 Explain how characteristics of living things are passed on from generation to generation. Being Able to Curl up both sides of the Tongue is under the control of a dominant allele at one gene locus. Homozygous Dominant rr Homozygous recessive RR Rr Heterozygous Inheritance for Tongue Rolling and Non-tongue Rolling Susan’s mom is a tongue roller. Her father is a non-tongue roller. Susan has three older brothers and one younger sister. Her three brothers are all tongue rollers. Her sister is a non-roller. What are the genotypes of each member of Susan’s family? R = allele for ability to roll the tongue r = allele for non-roller What are Susan’s Family Tongue Rolling Genotypes? Dad = rr (non-roller, recessive trait expressed) Sister = rr (non-roller, recessive expressed) Mom = Rr (heterozygous, mom had to donate the “r” allele to Susan’s sister and since mom is a roller she must have the “R” allele) Susan and her brothers = Rr (heterozygous, each child inherits an “r” allele from dad and because they can roll they each inherited an “R” allele from mom) Mark marries Susan. . . Mark’s mom is a non-roller and his dad is a roller. Mark’s two brothers are rollers. What is Mark’s genotype for ability to roll the tongue? Rr Mark and Susan are planning a family. What is the probability that Susan will deliver a roller, a non-roller? Punnett Square Mark S u s a n R r R Roller R R Roller R r r Roller R r Non r Roller r Genotypic Ratio 1:2:1 Phenotypic Ratio 3:1 After fourteen years of marriage... …are all happy ROLLERS !!! Mark Jessica Susan Ashley Baby Peas Don’t Go Gregor Mendel Father of Heredity Baby Peas Don’t Go Look, the Structure of DNA! Watson Crick DNA Model 1953 rr Rr If Mary and Peter are both Rollers, what are the chances for Anne to be roller, a non-roller ? rr Rr Key Concepts Traits Dominant Recessive Genetic material gene pair gene combination gene sorting Real-world contexts Common contexts Inheritance of a human genetic disease/disorder, such as sickle cell anemia A family tree focused on certain traits Examining animal or plant pedigrees. Sickle Cell Anemia http://www.bio.miami.edu/dana/250/25002_4print.html A particular species of bird can be brown or white. The white color is a recessive trait, while the brown color is a dominant trait. When two brown birds mate, is it possible for them to have white offspring? a. no because both parents have only genes for being brown b. yes, because offspring color does not depend on the genes of the parents c. yes, because both parents have and pass on the gene for being white d. no, because the parents can only pass on the dominant gene to their offspring. a. no because both parents have only genes for being brown Incorrect: You don’t know for sure if both parents have two genes for being brown (BB). They could have a Brown gene and a white gene (Bb) and still have the phenotype (what they look like) of white color Return to the question b. yes, because offspring color does not depend on the genes of the parents Incorrect: The color does depend on their genes. This is an inherited trait. Return to the question c. yes, because both parents have and pass on the gene for being white Correct: You don’t know for sure if both parents have two genes for being brown (BB). They could have a Brown gene and a white gene (Bb) and still have the phenotype (what they look like) of white color Return to the question d. no, because the parents can only pass on the dominant gene to their offspring. Incorrect: They have an equal chance of passing on the dominant and recessive gene if the contain both. The term dominant means that when an individual has two different genes for a trait the dominant is the one that shows up in the phenotype (appearance) Return to the question