Stamped DNA How imprinting affects inheritance A TIDBIT

Stamped DNA How ‘imprinting’ affects inheritance A TIDBIT by: Pat, Tammy, Marcie, Debbie, Eric and Tingting

Context Group 2: Heredity Teachable Unit: Epigenetics • Class: sophomore level genetics class ~ 50 -150 students • Previous concepts: Mendelian inheritance, DNA structure, intro molecular genetics • Reading assignment for class: Text information on epigenetics • This is the first lesson in the unit, but it will be followed by two lessons on mechanism and other epigenetic phenomena. • Since this topic has more challenging content, we have chosen to use guided active learning to help students construct a knowledge base, followed by more challenging homework assignments. • The unit will have 2 additional lessons or tidbits.

Misconceptions v All inheritance is based on DNA nucleotide sequence. v All human genes are equally expressed from both alleles. v All genetic diseases are caused by a point mutation. v The active genome of males and females is the same.

Unit Learning Goals and Flow of Content Students will understand: v v v The concepts of epigenetics. v Overview and definitions v Contrast with Mendelian Inheritance The molecular basis of different types of epigenetic phenomena. v Imprinting: Normal and Disease states v Histone Modification v RNA interference v Prions That epigenetics contributes to both diversity and disease. v Environmental impacts on the epigenome v Epigenetic determinants of cancer

Prader-Willi Angelman These two very different syndromes are caused by the same deletion

Epi Genetics

Learning Outcomes for Today v Students will define imprinting. v Contrast imprinting and Mendelian inheritance. v Predict an outcome from a genetic cross involving non-Mendelian inheritance.

What is Imprinting? v Imprinted chromosomes are “marked” v Imprinting differs in sperm and egg v Imprinting turns off specific genes v Imprinting does not change the nucleotide sequence CH 3

Think-Pair-Share/ review from last semester Hypothesize some ways that the DNA is imprinted? Formative Assessment; Bloom’s Synthesis (3/4)

DNA can be Methylated on cytosine residues Gene expression active Gene expression inactive -CH 3 (METHYL group)

Maternal Paternal CH 3 XGene A X Gene A Mutation Mendelian A mutation in Gene A may cause a change in phenotype when: Imprinted Dominant Recessive Maternally imprinted Paternally imprinted 1. The maternal copy is mutated Yes No No Yes 2. The paternal copy is mutated Yes No 3. When both copies are mutated Yes Yes With your clicker, press A for “yes” and B for “no” Formative Assessment; Recall; Bloom’s 1 Formative Assessment; Analyze; Bloom’s 3/4

CLICKER: Based on the figure below, which proteins are normally produced? Click A for B for C for D for protein A protein B BOTH NEITHER B A ANSWER = BOTH

CLICKER: Which proteins are produced with maternal deletion? Click A for B for C for D for protein A protein B BOTH NEITHER A ANSWER = only protein A is made

CLICKER: Which proteins are produced with paternal deletion? Click A for B for C for D for protein A protein B BOTH NEITHER B ANSWER = only protein B is made

Normal Maternal CH 3 Gene A Paternal deletion Maternal Paternal XGene A CH 3 Gene B A CH 3 XGene A B X Gene B [ B ] Maternal deletion Maternal Paternal [ Gene A A CH 3 X Gene B ]

Prader-Willi Angelman These two very different syndromes are caused by the same deletion

Compose a 1 minute essay that explains the basis for the difference between Prader-Willi and Angelman. Formative assessment; Bloom’s level Analysis 3

Homework: To further assess your understanding of Mendelian inheritance versus inheritance of imprinted genes 1. Define imprinting in your own words. 2. Look at the following pedigree and answer the questions below. • Is this disease dominant? Why or why not? • Is this disease recessive? Why or why not? • Can the disease be inherited from the paternal side? • Can the disease be inherited from the maternal side? • Does this show Mendelian inheritance?

Entrance Ticket: Parthenogenesis (“Virgin Birth”) v Parthenogenesis is the ability of some species to produce offspring without any male involvement v Parthenogenesis is observed in various animal species, but not mammals How could imprinting prevent parthenogenesis? Formative Assessment; Bloom’s Analyze, 4

SCIENTIFIC TEACHING Goals v Active Learning/Assessment Bloom’s Level/Verb Clicker Define Epigenetics and Think/Pair/ Share Brainstorming (think-pair. Imprinting Brainstorming share) Group problem solving Entrance ticket Summative: Homework/write in your own words Call-out Hypothesize/grapple with/3 -4 Define/1 Contrast imprinting and Worksheet activity/ Mendelian inheritance. individual/Peer v Assessment-all of above formative interaction/Group problem Individual take-home questions are summative solving/call out/clicker assessment v Diversity Recall/1 Predict an outcome from Formative/visual/clicker Auditory/visual a genetic cross involving questions non-Mendalian Social learning and individual work inheritance. 1 minute essay Predict/ 3 Analyze/3 -4 Compose/Explain/Analyze /3 Summative: Homework/ Analyze/Predict/relate/3 -4 Pedigree/Parthenogenesis