Genetics and Natural Selection Flashcards
Chromosomal Abnormality - Trisomy
Having one or more extra chromosomes
e.g. Down’s syndrome, Trisomy 21
Chromosomal Abnormality - Monosomy
Having only one of a pair of chromosomes
Rare in autosomes as embryos with monosomy not viable
e.g. Turner syndrome, on X chromosome (only in females as have another X to compensate)
Genetics - Homozygous
Alleles are the same
Genetics - Heterozygous
Alleles are different
Genetics - Dominant
Only one allele is necessary to produce characteristic
Genetics - Recessive
Both alleles must be the same to produce the characterstic
Genetics - Intermediate
Both alleles equally expressed in heterozygous pairs
Genetics - Autosomal Dominant
If the abnormal genes is inherited, the disorder is present
No carriers
e.g. Huntington’s disease
Genetics - Autosomal Recessive
The abnormal gene must be inherited from both parents in order for the disorder to be present
Carriers
e.g. Phenylketonuria
Genetics - X-Linkage
Genes on the X chromosome are affected so are male-prone disorders
Genetics - Sex-Linkage
Allele is located on the sex chromosomes
e.g. Fragile X Syndrome
Genetics - Sex-linked Dominant
Heterozygous mothers pass onto 1/2 of children
Genetics - Sex-linked Recessive
Both parents would need to pass on same allele
Genetics - Sex-limited
On autosomal chromosomes but triggered by sex hormones
Evolution
Animals and plants are dynamic species
Evolution is gradual and continuous
All organisms come from a common ancestor
Natural Selection
Adapting to a changing environment or maintaining state in a stable environment
Natural Selection - Assumptions
Variation within population
Inheritance of genetics from previous generation
Adaptation to current environment
Studying Genetics - Molecular Genetics
Looks at specific causes of behaviour by locating specific genes associated with behavioural traits
e.g. MAOA-L and violence
Studying Genetics - Molecular Genetics, Singe Gene Disorders
Only one gene is responsible for prevalence of a disorder
Studying Genetics - Molecular Genetics, Single Gene Disorders, Necessary
The effect cannot be present without the cause
Genetic disorders will only occur if a particular mutation is present
e.g. Huntington’s disease can only occur if the specific mutated gene is present
Studying Genetics - Molecular Genetics, Single Gene Disorders, Sufficient
The cause will always result in the effect but the effect can be present if the cause is not present
Genetics disorders will occur if the mutation is present but can also occur as a result of a different cause, in absence of the mutation
e.g. Duchenne’s muscular dystrophy
Studying Genetics - Molecular Genetics, Multiple Gene Disorders
Multiple genes, in combination with the environment and lifestule, produce disorders
Studying Genetics - Molecular Genetics, Multiple Gene Disorders, Gene-Environment Correlation, Passive
Child is the recipient of an environment as a result of the parent’s genetic tendencies which are also inherited
e.g. Parents have ‘musical’ genes and so have instruments in the home and go to concerts, the child is put into this environment where thier inherited genes flourish
Studying Genetics - Molecular Genetics, Multiple Gene Disorders, Gene-Environment Correlation, Active
Child’s genetic tendencies correlate to their environments
e.g. Children inherantly extroverted seek out stimulating environments
Studying Genetics - Molecular Genetics, Multiple Gene Disorders, Gene-Environment Correlation, Evocative
Child’s genetic predispositions evoke reactions from others which change the environment experience
e.g. Child is inherently naughty and those around them scold them and apply strict rules which makes the child want to rebel even more
Studying Genetics - Molecular Genetics, Multiple Gene Disorders, Multiplier Effects
Genetic or prenatal influences increase tendencies whihc are faciliatated by the environment
Studying Genetics - Molecular Genetics, Multiple Gene Disorders, Multiplier Effects, Bohman 1996
Percentage of petty criminality is much higher if individuals have both genetic and environmental risk factors
No risk < Environmental risk < Genetic risk < Environmental & Genetic risk
Studying Genetics - Quantitative Genetics
Use of observational and statistical methods to assess the extent to which variation in traits is influenced by genetics
Studying Genetics - Quantitative Genetics, Heritability
Estimation of the proportion of trait variance due to differences in genetics
From 0 (no genetic influence) to 1 (entirely genetic influence) Estimates are dependent on population, timing and environment
Studying Genetics - Quantitative Genetics, Measurement, Twin Studies
Compare similairites between MZ and DZ twins raised together and apart
If MZ = DZ, no genetic effect
If MZ > DZ, genetic effect
If MZ = 2DZ, entirely genetic effect
Studying Genetics - Quantitative Genetics, Measurement, Twin Studies, Riemann et al 1997
Compare MZ and DZ twins
Personality is 54% heritable
Studying Genetics - Quantitative Genetics, Measurement, Twin Studies, Error
Gene-Environment Correlation
MZ may be treated more similarly than DX
MZ share prenatal membranes
Studying Genetics - Quantitative Genetics, Measurement, Adoption Studies
Compare correlations between adopted and biological families
If biological > adoptive, genetic influence
If adoptive > genetic, environmental influence
Studying Genetics - Quantitative Genetics, Measurement, Adoption Studies, Lykken et al 1993
Look at MZ raised together and apart and DZ raised together
MZ together .49
MZ apart .42
DZ together .23
Similarity in MZ together and apart suggests genetic component but alos environment due to not being the same
Studying Genetics - Quantitative Genetics, Measurement, Adoption Studies, Error
Prenatal environment and early environment is shared before separation / adoption
Studying Genetics - Quantitative Genetics, Measurement, Animal Studies
Breeding of animal generations for selection of traits to indicate heritability
Studying Genetics - Quantitative Genetics, Measurement, Animal Studies, Benefits
Ethical
Can track mating
Can breed large populations
Control over exposure to conditions
Studying Genetics - Quantitative Genetics, Measurement, Animal Studies, Tryon 1940
Bred rats to diverge into ‘dull’ or ‘bright’ rats who could work their way out of a maze
Indicate heritability of intelligence / spatial awareness
Studying Genetics - Quantitative Genetics, Measurement, Complications
Overlapping of environments from separated twins
Assortative mating underestimates heritability
Malnutrition during childhood can deactivate genes and understimate heritability
Prenatal environments are not inherited but are from biological family
Studying Genetics - Quantitative Genetics, Measurement, Adoption Studies, Ingraham & Kety 2000
Schizophrenia concordance
0% adopted family
12.5% biological family
