genes Flashcards
definition of a gene
biological units of heredity
- sections of chromsomes
wa
define chromosomes
- long strands of DNA and proteins
what does DNA do with histones
DNA molecules are tightly wrapped around protein (histones), which provide structural support
how is a double helix formed
when two dna strands twist around each other to form a double- stranded helix
what does a nudelotide consist of
- sugar molecule
- phosphate molecule
- base (DNA)
what do nucelotides form
base pairs
what are base bairs turned into
arranged into sequences of 3s called codons
how many amino acids make up the proteins in the body
20
what are amino acids
building blocks of proteins
what does a gene have at the start and end of it
start and end codons
what are 5 functions proteins can do
- antibodies
- enymes
- messsengers (e.g hormones)
- structural proteins
- transport and storage
what is a codon
- triplets of nucleotides which code for amino acids
what is an amino acid
building block for protein
describe transcription and what stage is it
- stage 1
- DNA strand serves as a template for the synthesis of a complementary single strand of mRNA
- mRNA formed by RNA polymerase
what does RNA have instead of deoxyribose and thymine
ribose and uracil
what is translation and what stage is it
- stage 2
- ribosomes translate the RNA sequences to enzymatically assemble amino acids to form polypeptides
- DNA TO RNA TO PROTEIN
define genotype
an indivudls genetic makeup
define phenotype
an indidvuals observable characteristics
what is transcription definition
process by which a single strand of DNA serves a template for which a strand of RNA is built
what is translation definition
process by which the RNA is used to code for a series of amino acids
name 3 stages to cell division
- division of a cell must be accompanied by replication of DNA
- each DNA strands acts as its own template
- each progeny cell has one parental strand and one daughter strand
how do u mutations occur
in copying errors or damage to a parental strand which causes one or more wrong bases to be incorporated into the daughter strand
what does it mean when most mutations are innocuous
they are harmless and do not change the function of a protein
who experimented with pea plants
gregor mendel 1856-1863
what did gregor mendel do and discover
grew over 10,000 pea plants keeping track of progeny number and type
- discovered laws of inheritance
- found that genes come in pairs and are inherited as distinct units (one from each parent)
whats the alternative form of a gene
alleles
what is an allele
alternative form of a gene that forms different characteristics
what gene has 2 versions of long and short
5-HTT
which gene is associated with regulation of cortisol
SKA2
what happens with reduced levels of SKA2 protein
less suppression of cortisol release
what increases at SKA2 gene
methylation
what is methylation
silencing of a gene
whats the first gene to be linked to antisocial behaviour
MAOA (monoamine oxidase)
in 2016 what was found in Finnish criminals
the ones convicted of several violent crimes were more likely to possess the MAOA-L allele than nonviolent controls.
what does HE stand for and what is it
Heritability estimate, statistical indicator of genetic influence on variation of a trait
when the heritability estimate (HE=0) what does this mean
- no genetic influence, all the variation is due to the environment
when the heritability estimate (HE=1) what does this mean
-100% of the variation is due to genetic differences
what is the heritability estimate about
the influences of genes on the variation in a specific population
what is biological relatedness
The degree to which individuals share genetic material due to family relationships.
what does polygenic mean
that a trait is influenced by many genes
what single disorder can influence IQ
Phenylketonuria
what is the HE in childhood
0.4-0.5
what is the HE in adulthood
0.7-0.8
what are the 3 reasons the HE is higher in adulthood
- maybe fully developed IQ doesnt develop until adulthood
- maybe what we measure in children is not an accurate measure of IQ
- maybe we seek out environments that exaggerate our predisposition
what was found in environomental enriched children
when they were moved from a deprived environoment to a wealthier one they show an increase of 10-12 points
what was found in the measure of IQ in education (2 points)
- association between attendence and IQ
- small decrease in IQ over summer
what did the Minnesota study of twins show (1980)
genetics play a significant role in many human traits, even when twins are raised in diff environments, however environmental influences are still important
what type of evidence did the minnesota study show
anecdotal evidence
what variability was found in variety of traits in the minnesota study
50% (HE >.5) of variability observed in variety of traits was explained by underlying genes, for examples the tendency to be religious
what is the interplay between genes and the environment
our environment is shaped on the basis of inherited characteristics but genetics are expressed as a result of our environments
what are reaction ranges and who came up with the concept
the concept that we dont inherit set behaviour traits, but rather ranges of possible expression (BOTANAS ET AL., 2016)
what traits show a genetic contribution towards them
intelligence and personality
what did Henquet et al find about cannabis and psychosis
- small proportion of cannabis users develop psychosis (probs via dopamine system COMT gene)
- there are genetic difference in sensitivity to THC in cannabis and in likelyhood to develop psychosis
- BUT these predispositions interact with stress to result in cannabis
define psychopathy
a personality disorder characterised by antisocial behaviour, impaired empathy and egotistical traits
what is the HE in psychopathy
-0.5 (higher in childhood but correlated across lifespan)
what is the MAOA gene and what does it fail to break down and who found this
- low activity variant associated with developing psychopathy
- due to its failure to breakdown dopamine, serotonin and noradrenalin
-(Tracy D et al.)
what is charles Darwin’s theory of natural selection
organisms with traits that give them an advanatge are more likely to survive, reproduce, passing those traits onto offspring
- over generations these advantagous traits become more common in the population
define altruism
behaviour by an individual that increases the fitness of another individual while decresing the fitness of the actor
what was hamiltons genes- eye view and what year was it
- 1963, 1964
-* Asked whether genes could promote cooperative action by the
individual in order to pass on more copies of themselves - Fundamental in shaping our idea of genetic basis for altruism
- Here, genes are the replicators and individuals are just the
vehicles that carry out their actions
define kin selection
an evolutionary strategy that favours the reproductive success of an individual’s relatives
- even at cost to the individuals own survival
what is the coefficient of relatedness
r- the probability that you share a gene with someone else
what r stat do siblings share
r=0.5 (1/2)
how does altruism evolve and what does R,B,C stand for
r- relatedness
B- reproductive benefit to recipient
C- reproductive cost to altruist
- r x B > C
altruism is more likely to evolve when…
relatedness (r) is high
what animal shows an example of kin selection
orphaned red squirrels
what is kin recognition
an organisms ability to distinguish between genetic kin and non- kin
what does facial resemblence enhance
trust
what are the 2 mechanisms used by animals to recognise kin
proximity and phenotype matching
what is proximity
idea that animals often recognise kin based on spatial closeness or being raised together
what is phenotype matching
when an individual recognises kin by comparing physical traits that are likely to be shared due to genetic relatedness
what is social grooming
act of grooming close relatives as a behaviour that enhances the survival and reproductive success of shared genes
- usually time matched
what was found about related dyads
did not time match to same extent as non- related dyads
- suggests pairs who are genetically related were less synchronised in their behaviour over time compared to non- related
what is inclusive fitness
a measure of an individuals total genetic success
