Genes and Behaviour Flashcards
1
Q
GENES & BEHAVIOUR
A
- genes produce proteins NOT beh
- BUT can influence beh via effects of proteins on neurons/hormones/brains/muscles
- resulting beh affected by environmental conditions where it develops (gene x environment interaction)
- expressed beh depends on said interactions
- genes influence learning mechanisms
- beh flexibility = key feature of most organisms
2
Q
GENES
A
- located on chromosomes (DNA coiled around histones) located in cell nucleus
- gene expression = transcription (DNA -> RNA) + translation (RNA -> protein)
- produce proteins (large complex molecules; do most cell work)
- genotype = entire gene set an individual prossesses
- phenotype = observable characteristics of individual influenced by genes x environment
- OMIM (Online Mendelian Inheritance in Man) = large searchable up to date database of human genes/traits
3
Q
PROTEINS
A
primary structure (amino acid) -> secondary structure (a-helixes) -> tertiary structure (polypeptide chains) -> quatemary structure (protein molecule complex) - include: antibodies/enxymes/hormones/structural components/transport/storage
4
Q
ALLELES & GENETIC DIVERSITY
A
- individuals have 1/2 alleles (variants) of gene BUT multiple alleles can exist in pop
- 74% = human eye colour variance (ie. dominant brown over blue = brown eyes)
AGOUTI GENE - involved in coat pattern/shading of mammals
- when upregulated hair follicle melanocytes switch from making black -> yellow pigment
- lethal alleles lead to death of homozygous recessive offspring
5
Q
POLYGENIC INHERITANCE
A
- quantitative traits often show polygenic inheritance (influenced by many genes each w/small effect) ie: height/skin/educational attainment/sex orientation
6
Q
EXTENT OF BEHAVIOUR TRANSMITTED BY GENES
A
SOKOLOWSKI (2001)
- challenges of beh genetics research
- difficulty in defining/quantifying beh
- environmental influences beh
- within/between individual beh variation
- involvement of many genes
- dif genes function in dif tissues at dif times during organism development
7
Q
PEROMYSCUS MICE BURROW STRUCTURE
A
WEBER et al (2013)
- deer mouse = grassy habitat/no escape tunnel
- oldfield mouse = open habitat/escape tunnel
- captive-reared mice placed in sand-filled arenas for first time; build species-typical burrows
- F1 offspring (deer x oldfield) = 100% escape tunnels
- backcrossed (F1 x deer) = 50% escape tunnels
- single dominant locus controls escape tunnel building
8
Q
FRUIT FLY LARVAE FORAGING
A
DE BELLE & SOKOLOWSKI (1987)
- sitters or rovers
- both beh types = wild-type phenotypes (70% rovers; 30% sitters in natural pop)
- female sitter x male rover = same phenotype (rover)
- female F1 x male F1 = 3:1 phenotypic ratio
- single gene influences beh expression BUT doesn’t encode it
9
Q
FRUIT FLY LARVAE FORAGING +
A
DE BELLE et al (1989)
- FOR gene encodes kinase G protein; affects neuronal activity (STM/LTM)
- sitters homozygous for recessive allele FOR^S
- rovers have at least 1 dominant allele FOR^6 copy
10
Q
MATERNAL MICE BEHAVIOUR
A
- fosB mice mutation causes maternal beh disruption ie. creating nest/cleaning pups/retrieving pups to nest/crouching for warmth/nursing
- single gene can determine phenotypic complex beh expression
- fosB products widely expressed in brain; mainly in preoptic hypothalamus area (critical for nurturing beh)
- fosB-deficient mice = normal motor beh/reproductive hormones/intact glands (ie. specific mutation effect)
11
Q
GENES X PHENOTYPES
A
- gene expression acts at dif phenotypic levels
- environmental influences act on gene expression/phenotype
- gene expression can influence:
1. other gene expression
2. cell/tissue/organ activity
3. developmental processes
4. brain/muscles/messenger systems activity -> beh expression
12
Q
PHENOTYPIC VARIANCE
A
- total phenotypic variance (VT) in trait based on genetic variance (VG) additive effects/environmental variance (VE); VT = VG + VE
- trait heritability ((h^2) = VG/VT) = phenotypic variance proportion associated w/genetic variance
- N.B. heritable ISN’T “genetically determined” (ie. height highly heritable in time of plenty; less in famine)
- response to selection (R = h^2 x S)
13
Q
SELECTIVE BREEDING
A
- artificial selection = mice selected for dif nest building levels/rate for maze-running ability
- genotype effects can be masked by environmental effects; enriched environment improved performance of maze-dull rats
- restricted environments prevented inherited ability expression
14
Q
GENETIC MUTATION
A
- most harmful/neutral in effects; rarely beneficial
- wild-type = >1% frequency alleles
- mutant = <1% frequency alleles
- monomorphic = gene w/1 wild-type allele
- polymorphic = gene w/>1 wild-type allele
- knockout = lab strain where known mutation inactivates/knocks out gene’s normal function
15
Q
GENETIC MUTATION TYPES
A
GERM-LINE - germ-line mutation - entire organism carries mutation - half of gametes carry mutation SOMATIC - gametes - somatic mutation to embryo - patch of affected area on organism - no gametes carry mutation
