EPIGENETICS: SUPPLEMENTAL MATERIALS
EPIGENETICS: SUPPLEMENTAL MATERIALS
An answer to the question: "Why are some genes expressed and not others?" the Epigenetics module on Learn.Genetics explores some of the mechanisms responsible for the differential expression of genes, and how environmental factors influence those mechanisms.
Assessment questions for online activities are provided for use in generating discussion, creating worksheets, tests and quizzes, and providing fuel for thought. See the National Science Standards that this module addresses.
WHAT IS EPIGENETICS ?
The development and maintenance of an organism is orchestrated by a set of chemical reactions that switch parts of the genome off and on at strategic times and locations.
Epigenetics is the study of these reactions and the factors that influence them.
THE EPIGENOME AT A GLANCE
An animated introduction to the epigenome and how it instructs DNA.
Learning Objectives
The epigenome influences gene expression.
Assessment Questions
- Describe the physical state of the genome (tightly wrapped, or relaxed) when genes are inactive.
- Describe the physical state of the genome when genes are active.
GENE CONTROL
Change the level of gene expression in a cell with a turn of the dial!
A close look at the action of epigenetic molecules on the structure of DNA, and the resulting mRNA transcripts as the level of expression changes for the GFP gene in a glowing cell.
classroom connection video
Learning Objectives
When a gene is tightly wound around histones and highly methylated gene expression is low.
When a gene is loosely wound around histones and acetylated, gene expression is high.
Assessment Questions
- Describe the following characteristics when a gene is active:
- Is the gene tightly or loosely wound around histones?
- Are there many or few methyl molecules attached to the gene?
- Are there many or few acetyl molecules attached to the genes associated histones?
- Are there many or few mRNA transcripts?
- Describe the following characteristics when a gene is inactive:
- Is the gene tightly or loosely wound around histones?
- Are there many or few methyl molecules attached to the gene?
- Are there many or few acetyl molecules attached to the genes associated histones?
- Are there many or few mRNA transcripts?
DNA & HISTONE MODEL
A 3-D cut-and-paste model depicting how histone, acetyl and methyl molecules control access to DNA and affect gene expression.
Preview
Download Print-and Go (PDF)
Video instructions for this activity
Learning Objectives
- DNA is coiled around histones.
- Tightly coiled DNA is inaccessible to gene reading machinery.
- Methyl molecules bind to DNA and block access to genes.
- Acetyl molecules bind to histones and improve access to genes.
THE EPIGENOME LEARNS FROM ITS EXPERIENCES
Epigenetic tags record the gene-regulating signals the cell receives.
Learning Objectives
Signals from the environment influence gene expression by acting on the epigenome.
The epigenome helps cells "remember" the sum total of signals they have received that affect gene expression.
Assessment Questions
- True or False. Cell signals play a a role in shaping gene expression only during development.
- What molecule is primarily responsible for carrying cell signals to DNA?
- What are the two functions of gene regulatory proteins?
- Are epigenetic tags passed to daughter cells?
EPIGENETICS & INHERITANCE
Parents have a role in shaping the epigenome.
classroom connection video
Learning Objectives
When a gene is tightly wound around histones and highly methylated gene expression is low.
When a gene is loosely wound around histones and acetylated, gene expression is high.
Assessment Questions
- Describe the following characteristics when a gene is active:
- Is the gene tightly or loosely wound around histones?
- Are there many or few methyl molecules attached to the gene?
- Are there many or few acetyl molecules attached to the genes associated histones?
- Are there many or few mRNA transcripts?
- Describe the following characteristics when a gene is inactive:
- Is the gene tightly or loosely wound around histones?
- Are there many or few methyl molecules attached to the gene?
- Are there many or few acetyl molecules attached to the genes associated histones?
- Are there many or few mRNA transcripts?
FUNDING
Funding for this project was provided by a Science Education Partnership Award from the National
Center for Research Resources, a component of the National Institutes of Health.
|
EPIGENETICS & THE ENVIRONMENT
The genome dynamically interacts with the environment as chemical switches that regulate gene expression receive cues from stress, diet, behavior, toxins and other factors.
IDENTICAL TWINS: PINPOINTING ENVIRONMENTAL IMPACT ON THE EPIGENOME
Why do the physical characteristics of identical twins diverge as they age?
Follow the interaction of the environment and the genome in a pair of twins over time and learn how twins can help identify genetic traits.
Learning Objectives
Epigenetics can lead to differences in genetically identical twins.
Assessment Questions
- Often, the physical characteristics of genetically identical twins become increasingly different as they age, even at the molecular level. Explain why this is so. (use the terms "environment" and "epigenome")
- Name 3-4 environmental factors that influence the epigenome.
- What is an imprinted gene?
LICK YOUR RATS
What kind of mother are you? Care for a rat pup and see how you shape its epigenome.
Learning Objectives
The nurturing behavior of a mother rat affects her pup's response to stress in adulthood by shaping the pup's epigenome.
Assessment Questions
- Explain how a high-nurturing mother rat shapes her pup's epigenome, and what that pup's response to stress will be.
- In rats, does licking by the mother activate, or deactivate her pup's GR gene?
- Explain how cortisol and the GR protein work together in the brain to relax a rat pup. You may draw a diagram.
- The rat nurturing example shows us how parental behavior can shape the behavior of their offspring on a biochemical level. Relate this to humans and think about the personal and social implications. Record your thoughts.
NUTRITION & THE EPIGENOME
What you eat can change your gene expression.
Learning Objectives
Dietary methyl influences gene expression.
A mother's diet influences the epigenome of her offspring.
Toxins can affect gene methylation.
Assessment Qustions
- Explain how the food we eat affects gene expression.
- Can the diets of parents affect their offspring's epigenome?
EPIGENETICS & THE HUMAN BRAIN
Epigenetic tags interact with genes that affect behavior.
Learning Objectives
Dietary methyl influences gene expression.
A mother's diet influences the epigenome of her offspring.
Toxins can affect gene methylation.
Assessment Qustions
- Explain how the food we eat affects gene expression.
- Can the diets of parents affect their offspring's epigenome?
SCIENTIST TALK
The Epigenome As an Interface Between the Social Environment
and Our Genome
Moshe Szyf Ph.D.
Department of Pharmacology and Therapeutics,
McGill University, Montreal Canada
Given in the Summer of 2008 during the Beyond the Central Dogma Summer Institute at the Genetic Science Learning Center
|
