Bio - Epigenetics Flashcards
DNA
Info used to create proteins.
Gene
Section of DNA that enables a specific function.
Transcription
Reading of info in DNA/genes by enzymes.
Histones
Protein that forms ‘bundles’.
Methylation
A methyl group suppresses gene expression by closing the histone structure.
Acetylation
A acetyl group promotes gene expression by opening the histone structure.
Reader
Proteins that stimulate/change activity by binding (neurotransmitters).
Writer
Enzymes that add methyl or acetyl groups.
Eraser
Enzymes that remove methyl or acetyl groups.
Genotype
The info present in DNA.
Phenotype
The result of the expression of your DNA in the environment.
Diathesis-stress
A model of disease that sees nature and nurture as interacting forces.
Describe how DNA is read
- Each part codes for its own proteins and a single string can have many outcomes depending on what parts are selected.
- The DNA is read (transcribed) by specialised enzymes in the same order every time, but parts we don’t need right now are ‘skipped over’.
- The result is RNA - this is then translated into proteins.
- The DNA must open up in order for enzymes to ‘read’ the code.
- This allows the RNA to be put together, mimicking the info in the DNA strand (gene) before being capped at both ends.
- DNA that’s able to open and be read in this way allows normal functioning.
The extent to which the genes are accessible (whether the DNA is ‘open’) is controlled by what?
Methyl groups - methylated genes cannot be read - this chemical causes genes to be ‘skipped’ when surrounding genes are transcribed.
What is the DNA coiled around?
Structures called histones.
What is caused as a result of the fact that methylated genes cannot be read?
This chemical causes genes to be ‘skipped’ when surrounding genes are transcribed.
What is epigenetics?
The study of gene replication by methyl modifications.
What do methyl groups do?
Modify the transcription of DNA without changing it.
What can cause methyl groups to be added to genes?
Environmental influences (e.g. environmental stress, dietary choices, UV light, drugs, chemical exposure, exercise or lack of exercise).
What environmental influences can cause methyl groups to be added to genes?
E.g. environmental stress, dietary choices, UV light, drugs, chemical exposure, exercise or lack of exercise.
What are applications showing that environmental influences can cause methyl groups to be added to genes, causing them to become risk genes?
`We see ‘risk genes for psychiatric disorder but the concordance rate is never 100%.
- E.g. dysfunctional COMT or SERT are risk genes for OCD, but we all have these genes.
- Even if you have two parents with OCD, you might not get it - this will depend on the environment you grow up in, which will modify the genes you inherit.
What proteins/enzymes will cause modifications to genes?
Writers, readers and erasers.
What health issues are linked to the process of gene modification caused by writers, readers and erasers?
E.g. cancer, autoimmune diseases, mental disorders and diabetes.
Is nature or nurture the cause of the development of illnesses?
Genes and the environment both contribute to the development of illnesses.
What does the environment do to our genes?
It changes the expression of genes to produce a phenotype that is different from the genotype.
Many environmental factors can contribute to this.
