Genetics – Mutations - Concord Consortium

Genetics – MutationsTeacher’s Guide1.0 SummaryThe Mutations activity is the seventh core Genetics activity and should be run afterXLinkage. It should take students approximately 45 minutes to complete thisactivity.2.0 Learning GoalsDriving Question: What happens when you change the DNA? How are mutationsinherited?Mutations and Mutations II are two activities that enable students to use BioLogica'sDNA model to make changes to the base pair sequences of dragon DNA andinvestigate the impact of these changes on phenotypes and the inheritance patternsthat emerge when dragons with mutated alleles are bred. Because both Mutationsand Mutations II use pedigrees, students should complete Monohybrid first.Mutations introduces students to mutations through the appearance of a novel traitin a pedigree. Students then explore the role of DNA in mutations. They can modifythe base pair sequences of particular dragon alleles and examine the impact of thesenewly created alleles on the appearance of a dragon.Mutations II builds on Mutations and Monohybrid by enabling students toinvestigate how mutations are inherited. It also gives the students more practice inusing Punnett squares to determine the probability of inheriting a mutated trait. Itshould be used after X-Linkage.Learning Goals Students will understand that genes are base-pair sequences in DNA whichdetermine traits.Students will recognize that the four bases form complementary base pairs(A-T and G-C) that link the two strands of DNA.Students will identify the four bases of DNA as adenine, thymine, guanine,and cytosine.Students will understand that mutations are changes in the base-pairsequences.Students will know that genetic mutations create new alleles.Students will understand that not all genetic mutations result in a change ofphenotype.Students will comprehend that some mutations are dominant and some arerecessive.Students will be able to differentiate between somatic and inheritablemutations.Teacher’s Guide: MutationsPage 1 of 10

Additional Teacher BackgroundDNA is the nucleic acid that stores and transmits genetic information from onegeneration to another. The structure of DNA is a double helix in which two strandsare wound around each other. Each strand is made up of a chain of nucleotides.The two strands are held together by hydrogen bonds between adenine and thymineand between guanine and cytosine.Mutations are changes in the DNA sequence that affect how that code is translated.Mutations can range from imperceptible to lethal. Gene mutations result fromchanges in a single gene. Chromosomal mutations involve changes in wholechromosomes. Somatic mutations occur in body cells such as the skin and cannot beinherited. Germline mutations occur in the germline cells or gametes of organismsand can be inherited.The DNA Model deals with gene mutation. Most gene mutations are point mutationsinvolving the substitution of one nucleotide for another. Substitutions generallychange one of the amino acids in a protein. However, when a point mutation alsoinvolves the deletion or insertion of a nucleotide the situation is more severe. In thiscase, frameshift mutation occurs and every amino acid that follows the point ofinsertion or deletion is affected. The protein can be changed so drastically that itcannot perform normal functions.Students will be able to make insertions, deletions, and substitutions to the DNA ofthe Dragon model. They will then evidence the change in the nucleotide sequencesas well as the resultant physical changes to the dragon Elvira.Teacher’s Guide: MutationsPage 2 of 10

3.0 Standards AlignmentAlignment to National Math and Science Standards (NCTM or NSES)ObjectiveStandardsStudents will learn that DNA is acomplex molecule.Students should know the informationpassed down from parents to offspring iscoded in DNA molecules.Students should know that each DNAmolecule in a cell forms a singlechromosome.Students will learn that changes inthe DNA of sex cells result inchanges in the genotype of theindividual.Students should know that only mutationsin germ cells could create the variation thatchanges cells and organisms.Students will learn about themodes of inheritance of mutations.Students should know that in all organisms,the instructions for specifying thecharacteristics of the organisms are carriedin DNA.Students will further their study ofprobability.Students should be able to use simulationsto construct empirical probabilitydistributions.Teacher’s Guide: MutationsPage 3 of 10

4.0Activity SectionsIn this activity, students explore the appearance of a novel trait in the pedigree andthe types of genetic changes that might be responsible. Students have a chance toview, identify, and modify DNA to produce the new allele and new trait. Studentsidentify the letters ATCG as part of the DNA code. They then match letters as thebase pairs A-T and C-G. Students identify the names of the molecules adenine,thymine, cytosine, and guanine. Students create substitution, deletion and insertionmutations to create new alleles. Students investigate how these new traits areinherited through the generations in order to determine dominance relationshipsamong new and existing alleles.4.1A New TraitStudents investigate a new trait that appears in a pedigree.Using their prior knowledge and pedigree tools, students determine that theunicorn trait can be inherited and that the new HU allele is dominant whenpaired with existing alleles.Teacher’s Guide: MutationsPage 4 of 10

Students explore then predict how likely unicorns are to appear now that theallele is present in the population.Teacher’s Guide: MutationsPage 5 of 10

We then stress the rarity of mutations4.2DNA ModelStudents then dive into the DNA model to become familiar with its parts and howthey relate to the chromosomes and alleles encountered in Introduction and Meiosis.View of Elvis’ chromosomes, click on a gene (red line) to view DNA.A series of screens familiarize students with BioLogica’s DNA model.Questions help students focus on the base pairs that form DNA.Teacher’s Guide: MutationsPage 6 of 10

View of DNA of Horns alleles. Red bar above base pairs shows where basepairs differ for the different alleles.Students learn how to make changes in the base pairs and are challenged tochange the dominant allele to match the recessive one.Change the DNA to make Elvis hornless.Students are asked about the relationships among DNA, chromosomes, genesand alleles and receive scores on their answers.Teacher’s Guide: MutationsPage 7 of 10

Summary for Part 2Teacher’s Guide: MutationsPage 8 of 10

4.3 Change the DNA, Get a MutationIn the following section students explore how the HU allele came to be (asubstitution) and investigate other mutations (insertions and deletions).Students substitute a base pair to create the HU allele.Inserting a base pair into the sequence creates a frameshift and a new alleleaw that is recessive to both existing Color1 alleles.Teacher’s Guide: MutationsPage 9 of 10

Students answer review questions and receive brief summary.5.0 Student ReportsYour students’ work with Mutations is logged and viewable on the MAC Project WebPortal at http://mac.concord.org. For each student, you can view a report containingquestions and answers.The next activity that students should use is Mutations2, an optional activity in whichstudents explore x-linked and lethal mutations through pedigree analysis.Teacher’s Guide: MutationsPage 10 of 10

Teacher’s Guide: Mutations Page 1 of 10 Genetics – Mutations Teacher’s Guide 1.0 Summary The Mutations activity is the seventh core Genetics activity and should be run after XLinkage.It should take students approximately 45 minutes to complete this