HEREDITYYYYYYY 2015 July 17 c/o: Aaron, Darcie, Diana, Geeta, Kristin, Rou-Jia

Introduction Our “teachable unit”: Heredity module Embedded within Introductory Biology course Prerequisites: None (high school level biology) Student population: First-year students, both majors or non-majors Rou-Jia

Introduction Our “teachable unit”: Heredity module Embedded within Introductory Biology course Prerequisites: None (high school level biology) Student population: First-year students, both majors or non-majors Our “teachable tidbit”: Sex-linked traits Rou-Jia

Introduction Our “teachable unit”: Heredity module Goals Our “teachable tidbit”: Sex-linked traits Objectives Rou-Jia

Introduction Our “teachable unit”: Heredity module Goals 1) Understand how genes and chromosomes relate to traits 2) Appreciate how traits are passed on from parents to offspring 3) Comprehend the inheritance of genetic disorders Our “teachable tidbit”: Sex-linked traits Objectives Rou-Jia

Introduction Our “teachable unit”: Heredity module Goals 1) Understand how genes and chromosomes relate to traits 2) Appreciate how traits are passed on from parents to offspring 3) Comprehend the inheritance of genetic disorders Our “teachable tidbit”: Sex-linked traits Objectives 1) Be able to diagram a single-trait sex-linked cross and predict genotypic/phenotypic percentages. 2) Determine if a genetic disorder is sex-linked by analyzing a pedigree. 3) Distinguish between dominant versus recessive genetic disorders. Rou-Jia

Prior knowledge From the previous class: Concepts/definitions students should be familiar with: heterozygous vs homozygous recessive vs dominant genotype vs phenotype carrier autosomal single-trait crosses Punnett squares Aaron

Sex-linked traits What is a sex-linked trait?!? Aaron

Sex-linked traits What is a sex-linked trait?!? Definition: A trait whose gene is located on a sex chromosome (almost always the X-chromosome). Aaron

Sex-linked traits What is a sex-linked trait?!? Definition: A trait whose gene is located on a sex chromosome (almost always the X-chromosome). Why is this important/why should we care? Aaron

Sex-linked traits What is a sex-linked trait?!? Definition: A trait whose gene is located on a sex chromosome (almost always the X-chromosome). Why is this important/why should we care? Common sex-linked diseases: Colorblindness Hemophilia Duchenne muscular dystrophy Implications for genetic counseling Aaron

Clicker Question! Which of the following genotypes is representative of an affected female for hemophilia, an X-linked recessive disorder? A.AA B.X a Y C.aa D.X a X a E.X A X a Aaron

Clicker Question! Which of the following genotypes is representative of an affected female for hemophilia, an X-linked recessive disorder? A.AA B.X a Y C.aa D.X a X a E.X A X a Aaron

Clicker Question round 2 Which of the following genotypes is representative of a carrier for hemophilia, an X-linked recessive disorder? A.AA B.X a Y C.aa D.X a X a E.X A X a Aaron

Clicker Question round 2 Which of the following genotypes is representative of a carrier for hemophilia, an X-linked recessive disorder? A.AA B.X a Y C.aa D.X a X a E.X A X a Aaron

Clicker Question round 2 Which of the following genotypes is representative of a carrier for hemophilia, an X-linked recessive disorder? A.AA B.X a Y C.aa D.X a X a E.X A X a Do you think males can be carriers for sex-linked disorders? Why? Aaron

Pedigrees! What is a pedigree? A visual representation of family history for a trait. Standard notation for analyzing/constructing a pedigree: Diana

Pedigrees! What is a pedigree? A visual representation of family history for a trait. Standard notation for analyzing/constructing a pedigree: Diana

FemaleMale Pedigrees! What is a pedigree? A visual representation of family history for a trait. Standard notation for analyzing/constructing a pedigree: Diana

FemaleMale Descent Line Mating Line Pedigrees! What is a pedigree? A visual representation of family history for a trait. Standard notation for analyzing/constructing a pedigree: Diana

FemaleMale Descent Line Mating Line I.1I.2 Pedigrees! What is a pedigree? A visual representation of family history for a trait. Standard notation for analyzing/constructing a pedigree: Generation designation: I, II, III, IV… Individual designation: 1, 2, 3, 4… Diana II.1II.2

FemaleMale Descent Line Mating Line I.1I.2 Pedigrees! What is a pedigree? A visual representation of family history for a trait. Standard notation for analyzing/constructing a pedigree: Generation designation: I, II, III, IV… Individual designation: 1, 2, 3, 4… Diana II.1II.2 Phenotype designation Trait Present Trait Absent

Pedigree activity Assume the pedigree below displays information about a recessive, X-linked disorder. Work with a partner to fill in the phenotypes for generation I individuals and genotypes and phenotypes for generation II individuals. Working together in pairs, fill out the provided worksheet XAYXAYXaXaXaXa XAXAXAXA XaYXaY Kristin

FemaleMale Descent Line Mating Line I.1I.2 Pedigrees! What is a pedigree? A visual representation of family history for a trait. Standard notation for analyzing/constructing a pedigree: Generation designation: I, II, III, IV… Individual designation: 1, 2, 3, 4… Kristin II.1II.2 Phenotype designation Trait Present Trait Absent

Pedigree activity Assume the pedigree below displays information about a recessive, X-linked disorder. Work with a partner to fill in the phenotypes for generation I individuals and genotypes and phenotypes for generation II individuals. Working together in pairs, fill out the provided worksheet XAYXAYXaXaXaXa XAXAXAXA XaYXaY Kristin

Pedigree activity Assume the pedigree below displays information about a recessive, X-linked disorder. Work with a partner to fill in the phenotypes for generation I individuals and genotypes and phenotypes for generation II individuals. Working together in pairs, fill out the provided worksheet XaYXaYXAXaXAXa XAXaXAXa XAYXAYXaXaXaXa XAXAXAXA XaYXaY Kristin

If II.2 and II.3 have children: 1) Is it possible for them to show the trait? 2) If so, can both boys and/or girls show the trait? XaYXaYXAXaXAXa XAXaXAXa XAYXAYXaXaXaXa XAXAXAXA XaYXaY What about Generation III?

Mating activity for Generation III! Instructions You have each received a pair of cards representing alleles for the proud parents-to-be from Generation II. Now: 1)Find a partner with the opposite color cards. 2)Hold your cards behind your back, one in each hand. 3)Have your partner randomly select one of your hands. 4)Place your selected card on the table. 5)Repeat 3-4 with your partner’s cards. 6)Now define your offspring’s genotype. 7) ONE OF YOU report your offspring by clicking the appropriate choice. Geeta

Click in the resulting genotype of your offspring! XaYXaYXAXaXAXa XAXaXAXa XAYXAYXaXaXaXa XAXAXAXA XaYXaY A.X a X a B.X A X a C.X a Y D.X A Y Mating activity for Generation III!

Main takeways from today You should be able to define what a sex-linked trait is and understand their heredity. You should be able to analyze a pedigree and predict the phenotypes and genotypes of the offspring. Darcie

Summative Assessments Darcie

1)Colorblindness is an X-linked recessive trait. If a father who is X R Y has children with an X r X r mother, what is the probability (percentage) that a daughter born to the couple would be colorblind? a. 0% b. 25% c. 50% d. 75% e. 100% Darcie

1) Analyze the following pedigree for the pattern of inheritance, and answer the following questions. Assume that individuals II-1 and II-4 do not have the detrimental allele. Is this a dominant or recessive trait? Additionally, circle the couple that best supports your reasoning and explain. Is this a sex-linked trait? Why or why not? What is the genotype of individual I-1? Explain your reasoning. Darcie