PSY2003 SEMESTER 2 - WEEK 2 Flashcards
what is Mendel research
dichotomous traits, one form or another but never in combo
outline origin for a punit squares
replication in pea plant (green, yellow)
GG, Gy, Gy, yy
apply phenotype to pea plant punit
traits = yellow vs green
apply genotype to pea plant punit
genetic material = GG
apply allele to pea plant punit
different forms of gene that controlling same trait = G, vs y
apply heterozygous to pea plant punit
Gy
apply homozygous to pea plant punit
GG, yy
apply types of genes to serotonin transporters
2 forms = long (l), short (s)
but l not dominant to s = additive effect
known as A, meaning additive genetic event
what does A mean in behavioural genetic equations
additive genetic event
define genotype
genetic information about a organism
define phenotype
physical characteristics/expressions of a gene
define allele
variant of a gene, 1 inherited per parent
summarise base pairs of DNA
double-strand Helix, adenine + thymine, cytosine and guanine
uracil in mRNA
summarise stages of transcription
replication, dna strand unwinds and pair spare bases to create new double helix- mRNA
make proteins by translation and use mRNA, codons
RNA is single strand, bases pair up with DNA
copy of DNA in mRNA finds free amino acids in cytoplasm and pair up to form separate DNA strands (zipped up with ribosome)
each letter of 3 corresponds to a particular aa
what enzyme makes serotonin, apply genetics to mutant forms that make less serotonin
mutant form of tryptophan hydroxylase make 80% less serotonins, applies to depression
outline results from Zhang (2005) regarding mutant forms of typtophan hydroxylase gene
less mutant genes in control than depression cohort
but many of clinically depressed havent got the mutants
what are different forms of serotonin gene sometimes link to
short allele may link to depression
how can we solve issues regarding if short allele of serotonin impacts depression
brain scan, ppt judges angry/afraid face and study response of amygdala
shorter allele has higher brain activation to negative emotion
make brain over respond to negative emotion = risk factors in depression
however many have short gene and no depression - roles of environment too
give research example of environmental impacts in depression
Brown (1993)- depressed patient reports more severe stress in previous year than a control
Caspi (2003) subjects from Dunedin multidisciplinary health+development study into diathesis stress, outline method and their finding
divide ppt into groups of form of serotonin transporter gene and measure depressive symptom
but no difference in number of stressful events between genetic groups
number of stressful event nonsignificant and genotype non significant but interaction highly signfiicant
suggesting if has more 5HT-T gene short versions, more likely is depressed but is only when combined with a stress event
what is serotonin also referred as
5 hydroxytryptamine (5HT)
define polymorphism
genetic/molecular way for getting alleles,
with actual difference between short and long form of serotonin transporter gene at physical start of gene (promoter region)
what did ppts with 1 and 2 copy of short allele of 5-htt promoter polymorphisms express
more depressive symptoms, diagnosis, suicidal ideation
what is short allele associated with in depression in general
lower transcriptional efficiency of promoter, but inconclusive evidence regarding direct association to depression
suggested to moderate serotonergic response to stress
give evidence from mice experiment for GxE
disrupted 5-HTT homozygous and heterozygous strains showed more fear behaviours, more increased stress hormones compared to homozygous control but in absence of stress no differences
give evidence from macaques experiment for GxE
short allele associated with less serotonin function in those reared in stressful condition but not normal
give evidence from human neuroimage stress responses for GxE
neuroimaging showed stress response mediated by variations in 5-HTTLPR = humans with 1 or 2 copies of short allele showed more amygdala activity to fear stimulus than homozygous for long allele
explain application for MAOA genes
moderate childs sensitivity to maltreatment = a high affinity for 5-HTT raising chance of protective effect in LL
give negative evaluation of GxE, regarding serotonin genetics
inconsistent evidence in direct relation between 5-HTTLPR and depression and ignore past stress history for patient
cannot test hypotheses
give positive evaluation of GxE in serotonin genetic
GxE interaction for seronin and MAOA gene suggest evolutionary model with genetic variants maintained at high prevalence in population promoting resistance against environmental pathogens
positive implications for psychiatric genetic researching
