Genetics and Epigenetics Flashcards
Mendel
Inheritance of traits
Pea’s study he observed that traits were passed down through dominant and recessive genes.
Chromosomes
Single-cell protein that keeps DNA wrapped around histones.
Study of Meiosis
Each cell contains 23 chromosomes, 22 equal in both genders.
The 23rd pair is the sex chromosome which dictates gender.
XX Female and XY male
Female egg produces X and Male sperm produces Y
Genome
Organism complete set of DNA, including all its genes.
It contains information needed to build and maintain the organism.
Heritability
Changes to the DNA sequence are passed along across generations
Genotype
Determines potential characteristics
Homozygous: alleles are the same.
Heterozygous: alleles are different.
Phenotype
Observable characteristics from the interaction of genotype and environment.
different alleles code for different phenotypes.
Single Gene Disorders
Gene Mutations
Cystic fibrosis
Sickle cell disease
Chromosomal disorders
abnormal number/structural arrangement of chromosomes
Down’s syndrome
Complex/Multifactorial Disorders
Acquired mutations: cells don’t replicate as they should
Exogenous causes: environment, diet, substances, exercise, toxin exposure.
Jean-Baptiste Lamark: Lamarckian theory
Acquired traits in response to the environment experienced over the lifetime will be transmitted to offspring.
Elongation of the neck in giraffes as trees grew taller.
Epigenetics
The study of heritable changes caused by mechanisms other than changes in the underlying DNA sequence
The modification of DNA or alteration of associating proteins.
Soft inheritance
Reversible
Behavioral epigenetics
Experiences within our environments can lead to long-term effects on the brain and subsequently behavior.
They can be passed across generations.
Factors influencing epigenetic variation
Stress
Drug use
Social interactions
Pesticides
Smoking
Nutrition
Hormones
Nurture
Experiences occurring during fetal development can have long-term effects.
The brain and body are developing rapidly, providing a window of opportunity for variation.
Post-natal maternal care gives rise to variation in brain and behavior. Can lead to postpartum depression
Gene expression
DNA is wrapped around a cluster of proteins called histones.
Gene expression requires the unwrapping of DNA.
DNA methylation
Repression of a gene expression when methyl chemical groups attach to DNA.
Acetylation
Activates gene expression.
Epigenetics and stress
Early life experiences and maternal care can influence the epigenetic marks on genes related to the stress response.
Rats born with gene-silencing epigenetic marks on receptors that handle stressful situations demonstrated removal of marks when the mother gave attention(licked or groomed) to the baby, returning gene function.
Transgenerational impacts mediated by maternal care
Maternal experience, communal nursing, juvenile social experience, and stress in the first generation, induce epigenetic changes in itself and continuing generations.
Human Prenatal Maternal Stress: Quebec Ice Storm
Women pregnant during disaster reporting objective hardship correlated with DNA methylation levels, genes related to immune function.
Subjective distress was uncorrelated.
Dutch Famine Study
Prenatal exposure to famine during World War II demonstrated individuals in utero during the famine had a higher risk of certain health conditions, such as cardiovascular disease and obesity, later in life.
Agouti yellow mouse
Prenatal exposure to vitamins, feed to the mother during pregnancy, were able to change the baby’s fur color without any gene mutation.
Michael Meany: Postnatal stress
Rats raised by less-nurturing mothers have more methyl groups attached to the promoter region of the GC receptor gene, blocking access by transcription factors that turn the gene on. Resulting in the baby having fewer receptors produced not allowing shutdown of stress response easily.
Enzymes can reverse DNA methylation of the GC receptor gene, reversing the effects of a low-nurturing mother on the pup’s response to stress.
Epigenetic modulation
Environmental exposures, stresses, diet, and lifestyle can all induce epigenetic changes that determine whether genes are turned on or off.
Exercising: Rat Study
Exercise vs non-exercising rats are exposed to swim stress test.
Swimming behavior and dentate gyrus changes(hippocampus)
Exercising: Human study
Exercise related to the demethylation of genes involved in energy metabolism
Environmental experiences
Exposure to pesticides induces epigenetic variation in sperm leading to infertility.
These effects can persist over multiple generations.
