A TIDBIT by: A TIDBIT by: Pat, Tammy, Marcie, Pat, Tammy, Marcie, Debbie, Eric and TingtingDebbie, Eric and Tingting

Stamped DNA Stamped DNA How ‘imprinting’ affects How ‘imprinting’ affects inheritanceinheritance

Group 2: Heredity

Teachable Unit: Epigenetics

Context

•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 All inheritance is based on DNA nucleotide

sequence.

All human genes are equally expressed from both alleles.

All genetic diseases are caused by a point mutation.

The active genome of males and females is the same.

Unit Learning Goals and Flow of Content

Students will understand:

The concepts of epigenetics. Overview and definitions

Contrast with Mendelian Inheritance

The molecular basis of different types of epigenetic phenomena. Imprinting: Normal and Disease states

Histone Modification

RNA interference

Prions

That epigenetics contributes to both diversity and disease.

Environmental impacts on the epigenome

Epigenetic determinants of cancer

Prader-Willi Angelman

These two very different syndromes are caused by the same deletion

Learning Outcomes for Today

Students will define imprinting.

Contrast imprinting and Mendelian inheritance.

Predict an outcome from a genetic cross involving non-Mendelian inheritance.

What is Imprinting? Imprinted chromosomes are “marked”

Imprinting differs in sperm and egg

Imprinting turns off specific genes

Imprinting does not change the nucleotide sequence

CH3 CH3

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

activeGene

expression inactive

-CH3 (METHYL group)

Gene A Paternal

Gene A Maternal

XCH3CH3

XCH3CH3

Mendelian ImprintedA mutation in Gene A may cause a change in phenotype when:

Dominant

Recessive

Maternally

imprinted

Paternally

imprinted

1. The maternal copy is mutated

2. The paternal copy is mutated

3. When both copies are mutated With your clicker, press A for “yes” and B for “no”

Yes

Yes

Yes

No

No

Yes

No

Yes

Yes

Yes

No

Yes

Formative Assessment; Recall; Bloom’s 1

Formative Assessment; Analyze; Bloom’s 3/4

Mutation

Mutation

Mutation

CLICKER:

Based on the figure below, which proteins are normally produced?

Click A for protein A B for protein BC for BOTHD for NEITHER

ANSWER = BOTH

A

B

CLICKER:

Which proteins are produced with maternal deletion?

Click A for protein A B for protein BC for BOTHD for NEITHER

ANSWER = only protein A is made

A

CLICKER:

Which proteins are produced with paternal deletion?

Click A for protein A B for protein BC for BOTHD for NEITHER

ANSWER = only protein B is made

B

Gene A Maternal

XCH3CH3 Gene B

Gene A Maternal

XCH3CH3 Gene B

Normal

Paternal deletion

Maternal deletion

Gene A Paternal

Gene BX

CH3CH3

Paternal

Gene A Paternal

Gene BX

CH3CH3

Maternal

[ ]

[ ]

A

A

B

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

• 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?

1. Define imprinting in your own words.

2. Look at the following pedigree and answer the questions below.

Entrance Ticket: Parthenogenesis (“Virgin Birth”)

Parthenogenesis is the ability of some species to produce offspring without any male involvement

Parthenogenesis is observed in various animal species, but not mammals

How could imprinting prevent parthenogenesis?

Formative Assessment; Bloom’s Analyze, 4

SCIENTIFIC TEACHING

Active Learning

Clicker

Brainstorming (think-pair-share)

Group problem solving

Entrance ticket

Call-out

Assessment-all of above formative

Individual take-home questions are summative

Diversity

Auditory/visual

Social learning and individual work

Goals Active Learning/Assessment

Bloom’s Level/Verb

Define Epigenetics and Imprinting

Think/Pair/ ShareBrainstorming

Summative: Homework/write in your own words

Hypothesize/grapple with/3-4

Define/1

Contrast imprinting and Mendelian inheritance.

Worksheet activity/ individual/Peer interaction/Group problem solving/call out/clicker assessment

Recall/1

Analyze/3-4

Predict an outcome from a genetic cross involving non-Mendalian inheritance.

Formative/visual/clicker questions

1 minute essay

Summative:Homework/ Pedigree/Parthenogenesis

Predict/ 3

Compose/Explain/Analyze/3

Analyze/Predict/relate/3-4