PSYC 331: Ch 3: Biology and Behavior

CH 3: Biology and Behavior

-Genetics

-sperm and egg each carry 23 

-join to create 23 pairs (46 total)

-these pairs create a new unique human

-chromosomes

-first 22= autosomes

-last 2 (X and Y) = sex chromosomes

-egg carries an X, sperm carries either an X or Y

-XX = female, XY = male

-gender determined by sperm

-contain DNA

-genes = patterns in DNA

-21,000 genes per person (about)

-alleles = varying types of same gene

-2 of each, one from each parent

-genotype = set of genes inherited

-a person’s genetic blueprints

-phenotype = expression or outcome of genotype

-influenced by environment, specific alleles

-determined by allele pairs

-homozygous = two of the same type of alleles

-heterozygous = two different alleles

-dominance determines expression when heterozygous

-dominant: takes precedence in expression

-recessive: secondary in expression

-example: hair color

-Brown (B) dominant over blonde (b), Bb = brown hair

-Nature vs. Nurture

-genotype, phenotype and environment:

-parents’ genotypes contribute to child’s genotype

-child’s genotype contributes to child’s phenotype

-child’s environment contributes to child’s phenotype

-child’s phenotype contributes to child’s environment

-child’s environment contributes to child’s genotype

-behavioral genetics: studies inheritance of behavioral and psychological characteristics

-behavior and psychology are complicated, so are their inheritance

-polygenic inheritance: phenotype is determined by patterns across multiple genes (rather than 1 pair)

-Twins

-in BG, twin studies are often used to isolate genetic contributions

-psychological traits in identical twin are compared

-twins raised together

-twins separated at birth

-adoption studies used as well

-adopted children compared to biological family

-adopted children compared to adopted family

-bottom line: genetics contribute a lot but not all

-50% of personality, 50% of intelligence, etc. 

-Brain Development

-neurogenesis: creation of new brain cells

-100 billion neurons

-occurs mainly before birth

-axon extension: axon branch out toward connection points

-arborization: branching of dendrites (dendritic tree)

-increases neural ability to form new connections

-myelination: formation of myelin around axons

-begins before birth and continues through adolescence 

-different areas myelinate at different times

-myelination of different areas relates to infants’ abilities

-Synaptogenesis: generation of new neuronal connections

-neurons form trillions of connections with other neurons

-occurs in different areas at different times

-hyperconnectivity: your brain over connects itself

-connections form between unrelated areas

-synesthesia

-synaptic printing: unused connections are removed

-neural darwinism: “use it, lose it”

-40% of connections are pruned away

-plasticity: ability of the brain to adapt to situations

-two types 

-experience-expectant plasticity: neural connections formed based on input your brian expects based on humanness

-repurposing of unused brain areas for other functions

-experience dependent plasticity: neural connections formed based on input from personal experience

-our experiences shape our brain structure

-”bushy-brained” rats

-braille readers

-taxi driver