genes and behaviour Flashcards
do all genomes code for proteins?
no only a tiny proportion do
relationship between amount of dna and complexity of organism?
no clear relationship
may have lots of chromosomal dna but not be very complex
what % of our dna do we share with other humans and with chimpanzees and mice?
humans - 99.8%
chimpanzees - 98%
mice - 92%
similarity due to bodies doing largely the same things
what is a genotype?
set of genes individual possesses
what is a phenotype?
observable characteristics of an individuals
influenced by genes and enviro
what is an allele?
how many do individuals have compared to population?
a variant of a gene which determines 74% variance
have 1 or 2 of each gene but multiple can exist in population
what does it mean if genes on same chromosome?
inherited together
what is meant by the fact that humans are ‘diploid’?
2 copies of each chromosome (1 from mum and dad)
describe the difference between homo and heterozygous?
homozygous - 2 of the same allele so will express those alleles
heterozygous - different alleles from mum and dad so will express the dominant allele
describe the agouti gene?
influences coat pattern in mammals fur
alleles inherited determine colour of coat
what are lethal alleles?
lead to death of homozygous recessive offspring
e.g 2 copies of yellow coat gene (recessive) from heterozygous parents lead to death of mice as embryos
what is polygenic inheritance?
multiple different genes involved in inheritance
leads to additive genetic variance
describe polygenic inheritance of human skin colour?
alleles A B and C dominant correspond to more melanin so darker skin pigmentation
alleles a b and c recessive correspond to less melanin so light pigmentation
each parents produces 8 gametes which combine with each other in 64 different ways and results in total of 7 skin colours
name some challenges to behavioural genetics research?
difficult in defining and quantifying beh. compared to physical traits e.g eye colour
enviro influences on beh. - social and physical
may genes involved
variance within and between individuals - different beh. at different times
describe the burrow structure of mice behaviour related to their genes?
deer mouse
- no escape tunnel
- homozygousfor recessive alleles which don’t cause building of tunnels
oldfield mouse
- escape tunnel due to predation
- homozygous for allelels which cause building of escape tunnel
when crossbread 100% build escape tunnels (suggests allele for building tunnel dominant)
crossbread again with deer mouse 50% built escape tunnels so controlled by single gene
describe foraging in fruit-fly larvae describing relationship between genetics and behaviour?
rover (move) and sitter (stay) in search for food expressed through single gene (not coded)
F1 offspring (1st crossbread rover - dominant and sitters - recessive) all were rovers
crosshybrid offspring with each other (F2) and 3(rover):1(sitter) which displays that rover is dominant but much be 1 homozygous recessive sitter offspring
describe maternal behaviour in mice as showing behaviour related to genetics?
fosB mutation in mice causes disruption of maternal behaviour
fosB gene expressed in peroptic area of hypothalamus so fosB deficient mice only influence in maternal behavioour (not pleiotropic effect)
what can expression of a gene influence and what influences it?
acts on different phenotypic levels and influenced by environment at each stage e.g diet:
expression of other genes
activity of the cell, tissues and organs
developmental processes
activity of brain, muscles and messenger systems (behaviour)
what are traits determined by?
genes and enviro in conjunction
so continuous variation
what can quantitative traits be?
morphological - height
physiological - hormone
behavioural
what is meant by ‘norm of reaction’?
pattern of phenotypic expression of a single genotype across a range of environments
what does total phenotypic variance based on?
Vt = Vg + Ve
phenotypic variance = additive effects of genetic variance (Vg) + environmental variance (Ve)
what is trait heritability?
equation and description?
h^2=genetic variance / total variance in that trait
proportion of phenotypic variation which is associated wih genetic variance
what is the equation for aritificial selection of heritable traits?
h^2 = R/S R = response to selection S= strength of selection
if h^2=1 then full resemblance
give an example of effects of genotype being masked by environmental effects?
enriched environment improves performance of maze dull rats but restricted environment prevents expression of inherited ability
no longer masked when environment fair
when are alleles termed wild-type or mutat?
mutant when frequency <1%
wild-type when >1%
when are genes known as monomorphic and polymorphic?
mono - gene with 1 wild-type allele
poly - gene with >1 wild-type allele
difference between germ-line and somatic mutation?
germ-line in sperm/egg cells so gametes produced will contain mutation
somatic not in sex cells so not transferred to next generation
what may increase mutation above spontaneous levels?
mutagens e.g oxidative radicals
radiation
example of genetic mutation’s impact on behaviour?
social amnesia
males unable to produce oxytocin then inspects same female mouse for the same amount of time as if unfamiliar
what does monozygotic mean?
developed from same zygote (fertilised egg)
how to use twins to show genetic effects on behaviour?
high correlation in behaviour when monozygotic twins living apart in different environment as only thing they share is 100% of the same genes
what is the relationship between genes and behaviour?
genes produce proteins which can influence behaviour through effects on e.g neurons and hormones
resulting behaviour affected by environmental conditions in which it develops
where are genes located?
located on chromosomes (DNA coiled around histones) located in the cell nucleus
which 2 processes are involved in gene expression?
- transcription - dNA copied to RNA using RNA polymerase enzyme
- translation - mRNA decoded in ribosome to produce specific amino acid chain
what are the products of genes and what can they be used for?
product = proteins
complex, large molecules doing most of work in cell:
forming antibodies, enzymes, hormones, structual components and transport/storage
