Biological psych 5: Gene-environment interactions (Lec 29) Flashcards
Name the 2 main functions of a gene, which is part of your DNA sequence
- Duplication (a gene can make other genes)!
- Transcription: Making mRNA
Name 3 functions of RNA
– Can be used to regulate genes
– Can have enzymatic activity (bringing about a biochemical reaction)
– Translation: Making protein (this is what we usually look at at the level of behaviour)
Name 4 functions of proteins
– Regulate genes
– Has enzymatic activity (bringing about a biochemical reaction)
– Has structural role (forming a cytoskeleton within the cell)
– Is used in signaling: eg neurotransmitters/ hormones
What is the difference between translation and transcription?
Translation is the process of RNA translating into protein
Transcription is the process of genes making mRNA
Which 4 levels can the environment regulate genetic activity?
- Transcriptional control (determining whether the DNA is read off and transcribed into mRNA),
- Translational control (is the mRNA tranlated into protein?
- Post-translational control (proteins can change their structure dynamically and also change the level /efficiency at which proteins act as enzymes within the cell).
- Environment can alter genetic structure itself
How might scientists measure gene expression?
By measuring mRNA
How might scientists measure protein translation?
By measuring proteins
How might scientists measure post-translational modification?
By measuring protein variants and isoforms
give an example for the model of gene-environment interaction: Genetic and environmental effects might
be independent but additive eg P= A+C+E
Twin studies: shared genetics and similar environment create additive effects
Phenotypic variance= (A) addition variation in genetic background + (C) common environment +E (unique environment of individual)
Define phenotype
observable characteristics which result from genetic/env interaction
How did bright and dull rats benefit from enriched environments?
How about restricted environments?
Dull rats showed brightness improvement in enriched environment but it made no difference for bright rats.
Opposite affect for restricted env: Didn’t affect dull rats but bright rats suffered
What is the effect of HRT (estrogen) on women with and without the apolipoprotein E (ApoE) ε4 allele who have been diagnosed with Alzheimers?
It slows down the effects for women without the ε4 allele, but has no effect for women with the ε4 allele
Chemical modification within cells which can cause permanent change is called:
Epigenetics
Genes for serotinergic activity are modified by the environment. How does this affect grasshoppers?
some of them turn into locusts!
Describe the seminal Michael Meaney study on rat mums’n’pups, and what were the outcomes? (Name 2)
Adoption study pairing high-maternal (H) care mums w non-biological pups from both H and L mums, and low-maternal (L) care mums w non-biological pups from both H and L mums.
Rat-pups echoed adoptive mum behaviour rather than bio mum behaviour when they had their own pups. They also exhibited highly anxious behaviour in general for the rest of their lives.
What is insituhybridisation?
radioactive marker which binds to MRA to be observed (looking at gene-expression in the brain)
Why are glucocorticoid receptors in the hippocampus important?
Negative inhibition control over stress response
What do high levels of glucocorticoids in the hippocampus indicate?
A fully functioning stress regulatory system
The outcome of the Michael Meaney studies can be summed up as:
Type of maternal care (and not the genes passed from the biological mother) affects the pattern of gene expression (mRNA) in the stress hormone system in
adults.
Early life experience permanently alters genetic activity, regardless of the
genotype of the individuals.
mRNA can best be described as…
gene expression
What is ACTH and CRH/ CRF?
ACTH = adrenocorticotropic hormone
CRH/ CRF = Corticotropin releasing hormone/factor: Increases capacity to cope w stressors
How did the paint-brush pup stroking intervention affect the pups later in life?
What’s the take home message from the experiment?
Levels of stress hormones (ACTH = adrenocorticotropic hormone) were reduced in pups from the L (low maternal care) group who received paint-brush stroking.
Take-home message: environmental effects are indicative of genetic expression
How do methyl groups affect DNA, as opposed to Acetylation?
Methyl groups can make DNA harder to read (restrict DNA transcription into mRNA)
Acetylation has the opposite effect, making DNA ‘easier’ to read- encouraging mRNA transcription
High methylation and tightly bound histone is representative of what type of maternal care?
Low maternal care
High acetylation and loosely bound DNA is representative of what type of maternal care?
High maternal care
What is the indirect mechanism of emotional regulation, and what is it’s outcome?
The HPA axis: activity is altered through environment causing genetic expression/ inhibition
Not an environmental effect on “Genes for maternal behaviour”
– Effect is on genes important for emotional regulation
– Poor emotional regulation then spreads to negatively affect other behaviours, including maternal care
What is the difference between additive effects and gene-environment interactions?
Statistically, an interaction involves (at least) 2 variables which cannot be explained without the presence of the other. Additive effects are variables which are independent of one another, although additionally they can be examined together.
