Lecture 7: Genetics and Epigenetics

Question 1

What is a genome

Answer 1

organism’s complete set of DNA, including all its genes. An organism’s genome contains all the information needed to build and maintain the organism

Question 2

What is a Genotype?

Answer 2

Genotype: the part of the genetic makeup of an individual which determines their potential characteristics
* Ex: Brown eyes from dad (B) + blue eyes form mom (b) = Bb
* If alleles are the same (BB or bb), the organism is homozygous for the trait
* If the alleles are different (Bb) the organism is heterozygous for the trait

Question 3

What is a Phenotype?

Answer 3

Phenotype: the set of observable characteristics of an individual resulting from the interaction of the genotype with the environment
* Ex. Brown Eyes, curly hair, widows peak, sickle cell disease etc.
* Different alleles code for different phenotypes

Question 4

What is Lamarckian Theory

Answer 4

Acquired traits in response to the environment experienced over the lifetime will be transmitted to offspring

Question 5

The epigenetic inheritance system has been described as (BLANK) in comparison to genetics which is described as (BLANK)

Answer 5

‘soft inheritance’; ‘hard inheritance’

Question 6

Quebec Ice Storm

Answer 6

DNA methylation in offspring’s genes related to immune function
Epigenetic change due to objective levels of hardship vs sustained subjective stress

These data provide the first evidence in humans supporting the idea that PNMS results in a lasting, broad and functionally organized DNA methylation in several tissues in offspring. By using a natural disaster model, the investigators could infer that the epigenetic effects found in Project Ice Storm were due to objective levels of hardship experienced by the pregnant woman rather than to her level of sustained distress.

Question 7

Agouti rats and healthy diet

Answer 7

Obesity in the Agouti Mice
mother were fed Healthy foods - Supplement with Vitamin B12, folic acid, choline, betaine

Question 8

Michael Meany

Answer 8

• Rats raised by less-nurturing moms have more methyl groups attached to promoter region (the ‘on’ switch) of the GC receptor gene
• These methyl groups block access by transcription factors that turn the gene on
• As a result, fewer receptors are produced, and rat cannot shut down stress response as easily
• Good news: enzymes that reverse DNA methylation of GC receptor gene also reverse effects of unenthusiastic mothering on pups hormonal and behavioral responses to stress (The Seductive Allure of Behavioural Epigenetics, SCIENCE, 2010)
• Cross-fostering can reverse or induce epigenetic change – but is time dependen

Question 9

Exercise studies - within-life times

Answer 9

Rat study: Exercise vs non exercising rats then exposed to swim stress test
* Method: Exercise rats vs control
* Swim test exploration -> follow up exposure
* Findings: Swimming Behaviour Dentate Gyrus changes

Human study: Exercise related to demethylation of genes involved in energy metabolism