Genetics Flashcards
What is mendellian genetics
- work on pea plants help to understand dominant and recesssive genes
herminian gridd Gy - G GG- G yy- y Gy- G
What is a phenotype
trait
what is a genotype
gene
what is an allele
forms of a gene which affect the same trait
what is heterozygous
Gy
what is homozygous
GG yy
if a recessive gene is am autosomal chromosome it is ???
equally on males and females.
IF a recessive gene is on an X chromosome it will be
more often in males
What is Mitosis
cell division (before it divides it makes a complete copy)
what is meiosis
reproductive cell division
produces male and female gametes (have half the number of normal chromosome (23 pairs) so that when they join they have a full set.
What is rNA
RNA is formed in the nucleus of a cell it rewrites a sequence of DNA via transcriptions
What is mRNA
messenger RNA carries the code for building a protein to the ribosome
what is tRNA
transfer RNA picks up amino acids and brings them to the ribosome to make a specific protein.
what disorder is characterised by having 3 chromosome 21
down syndrome
150% proteins and overproduction of gene for APP amyloid precursos protein which results in early onset alzheimers
what is PKU
autosomal recessive gene (equally in males and females)
recessive (so can be a carrier)
inability to metabolise phenylaline (amino acid)
if not treated -> brain damage.
What is heritability (behavioural genetics)
It is an estimate of how much variance in some characteristics within a population is due to heredity.
varies between 0 and 1
behaviour genetics?
heretability is calculated comparing identical and non identical twins.
The heritability is twice the difference between the coorrelations for identical minus non identical twins
monozygotic share ?
dizygotic share?
MZ= 100% DZ= 50%
is heritability specific to the population
YES
does heritability look at differences between people or within
between
does high heritability mean the environment doesnt affect
NO
can heritability change over time
yes
If a Group of individuals share a highly similar environment, what effect does this have on the heritability estimate of a characteristic?
the estimate will be high
What is the flynn effect?
if genetic or prenatal influences produce a small increase in some activity the environment will magnify the effect
what is the Weinberger approach
suggests that genes lead to neuroohysiology straight to cognition.
What are the concordance rates for depression
MZ=60%
DZ= 15%
What are the two genes for depression
- the gene for trypotophan hydroxylas
2. gene for the serotonin transporter
how does the gene for tryptophan hydroxylase increase liklihood of depression>
in vitro cells with this gene make 80% less serotonin .
What did Zhang et al find (5HT)
out of 87 depressed people 9 people had the mutant gene
out of 219 control 3 had mutant gene (but had family history of mental health)
but not all of the depressed people have the gene .
how does the gene for the serotonin transporter affect depression
the gene has two forms the long L and short s form.
the short form is implicated in depression.
found that there was an increased response in the amygdala of those with the short vversion of the gene.
suggesting the brain of those with the short version over- respond to negative emotions.
What did brown find? (diathesis stress)
depressed patients: 84% stress in previous year
control: 32% in previous year.
what did caspi et al find?
serotonin transporter gene
No difference between the number of stressful events and genetic group but the interaction between the two was highly significant.
- diathesis stress model
