SOLVING GENETIC PROBLEMS

1. SOLVING GENETIC PROBLEMS Oksana Hrycyk John Miranda

2. Specific Expectations D2.3 Use the Punnett square method to solve basic genetics problems involving monohybrid crosses, incomplete dominance, codominance, dihybrid crosses, and sex-linked genes [PR, AI, C]. D3.3 Explain the concepts of genotype, phenotype, dominance, incomplete dominance, codominance, recessiveness, and sex linkage according to Mendelian laws of inheritance.

3. Genetic problems? No problem A man comes to a doctor and says “doctor, my wife is cheating on me. She and I are both black, my son however, is white…she must have done it with somebody else”. “ Another patient says that his wife is also cheating, they both have brown eyes but the baby is blue-eyed”. The doctor sights, he knows about dominant and recessive alleles. Do you know what that is?

4. Blue eyes from brown eyes video • http://www.youtube.com/watch?v=7QwTEKhVEDk

5. Most people think that we should look like our parents, however, most of us usually have different physical characteristics. • It all start by knowing about dominant and recessive alleles. • To understand this, we need to learn about phenotype, genotype, recessiveness, dominance, and how to use Punnett squares to solve genetic problems.

6. Lesson Sequence • Lesson One: Genotype Vs. Phenotype. • Lesson Two: DNA and Alleles. • Lesson Three: Recessiveness and dominance. • Lesson Four: Mendelian Laws. • Lesson Five: monohybrid crosses, dihybrid crosses, and sex-linked genes. • Lesson Six: Solving Genetic problems with Punnett squares.

7. Alleles Gizmos Lab • Log on: www.explorelearning.com • CLASS CODE: S56M7CTW34 • Students will solve mouse genetic problems with 2 traits. • Students interactively learn that crossing parents with certain dominant or recessive traits will produce a probability of offspring. • Students will understand the effects of dominant alleles in each crossing.

8. Dominant and Recessive Alleles Role-Play • There will be 2 groups of 12 students. Each student will represent Alleles. Two from the mother, two from the father (each parent will have dominant and recessive genes of a physical characteristic. Each student will be wearing different colour T-shirts for easy distinction), the other eight students will be used to provide the 4 possible genotype combinations. A captain will be selected for each group. • Each group will provide the probabilities of each possible combination in a certain amount of time.

9. Allele Role-Play Activity Continuation • The group to get all 4 combinations in the shortest amount of time will be the winner. • Another 5 exercises will be performed; students will select the parents’ genotype this time. • The group that gets the 4 combinations the fastest in all 6 exercises will get a box of cookies (the winners will be asked to share with the rest of the class to promote sportsmanship).

10. Genetically Modified Food Debate • Two groups of 5 students will be selected. One group in favour, the other against the use of genetically modified foods. • Each group will have a week to prepare and find valid research to support their case. A rubric will be used to assess their knowledge, communication, application, and technology. • A body of 5 judges will conduct the debate, prepare rules, and assess which group had a more influencing approach. Judges will make a half reflection on how debaters affected their decision. • The audience will be the jury who will decide which team was the winner. They will make a one-page reflection on how debaters affected their decision.

11. Punnett Square Problems • There will be various scenarios where students will solve the genetic problem by using Punnett squares. • Solutions to problems will be taken in class by using PowerPoint and clickers. Students will have the chance to chose their answers. Once answers are provided, a short explanation will be added.

12. Potential Student Difficulties and Solutions • Mathematics involved with Punnett Squares, specifically probabilities and binomial distributions. • Students will need to apply the Mendelian laws and determine probabilities to make predictions on the genotypes and/or phenotypes of the progeny. One method that may help overcome this difficulty is to spend a period reviewing these math concepts, as well as working through various applicable probability problems to clarify the methodology, including tips and tricks. These problems do not have to be genetics-based, but can be any typical probability problem, like rolling dice, drawing playing cards etc.

13. Potential Student Difficulties and Solutions • Understanding the notions of alleles, loci and genes, as they all can be conceived as somewhat similar. An allele is the various alternate forms of a single gene, and that single gene can have many alleles. A locus, on the other hand, is any specific location on a chromosome. We think the suggested Alleles Gizmos Lab and the Alleles Role Play may help clarify these differences as well as clarify various other questions about alleles and genes that may arise.

14. Potential Student Difficulties and Solutions • Distinguishing between the Mendelian laws: the law of segregation and the law of independent assortment. These two laws are quite similar, but define different ideas. The law of segregation states that two alleles of a single trait segregate during gamete formation and then one allele from each parent randomly unite at fertilization, while the law of independent assortment states that different pairs of alleles segregate independently of each other. • The Alleles Gizmos Lab and the Alleles Role Play can be used along with clear definitions and examples to help clarify any misunderstandings.

15. Safety Precautions • There is a virtual lab, so to avoid students accessing inappropriate internet sites, the school library will block any other website. The student will only have access to www.explorelearning.com for the gizmos lab. • For the role-play activity, students will be taken to the gym for ample space where they can easily and with speed move to work on their Punnett square activities.

16. Practical Applications • Practical applications of genetics in medicine and surgery. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1817215/pdf/brmedj02576-0029.pdf http://www.biophage.com/genetic-engineering.html • Disease diagnosis and prevention through genetic technology:http://www.michener.ca/ce/postdiploma/genetics_technology.php#what • Genetic Engineering in agriculture: Show students (after debate) how genetically modified food has helped increase crop yield and support the 7-billion world population. Foods with added minerals and vitamins. • Forensic medicine: Through the use of genetics, mysteries and crimes can be solved.

17. Differentiated Assessment • A diagnostic quiz will be administered testing student knowledge in probability and probability problems. • A Student Exploration Worksheet associated with the Alleles Gizmos Lab, which will be marked for Knowledge and Understanding, and Thinking and Inquiry (formative assessment). • Rubric for the Allele Role Play activity and debate for knowledge and understanding as well as communication and application. • Quizzes assessing the progress of their understanding, including definitions, Punnett squares and genetic problems. • Oral responses during in class discussions. • Unit test which true/false, multiple choice, matching exercises, math problems, short answers, and a reflection section (essay).