Exam 2 Flashcards
genotype vs phenotype
genotype: all of persons genes, inherited by biological parents
phenotype: persons observable characteristics and traits, combo of genes influenced by environment
cell parts and their connections
- DNA is in cell nucleus
- DNA tightly coiled around positions making up our CHROMOSOMES
- GENES are segments of DNA
- each GENE has unique address on CHROMOSOME
patterns of inheritance
AUTOSOMAL DOMINANT: 1 allele seen in phenotype, other silent. freckles, dimples, right handedness
AUTOSOMAL RECESSIVE: 2 silent alleles expressed. sickle cell anemia, left handedness
CODOMINANCE: 2 dominant alleles expressed, Blood type AB
INCOMPLETE DOMINANCE: Blend of 2 alleles expressed, hair colour or hair shape
Methods of studying heritability
TWIN STUDIES: compare phenotypes of monozygotic and dizygotic twins. if traits heritable, monozygotic will be more similar
ADOPTION STUDIES:child + biological parents vs adoptive parents. if heritable, similar to biological
TWIN-ADOPTION STUDIES: twins adopted into different households. if heritable, twins will be similar even if raised in different households
gene environment correlations
PASSIVE GENE ENVIRONMENT: characteristics of patent and child are similar
EVOCATIVE GENE ENVIRONMENT: characteristics of child evoke environments that support genetic traits
ACTIVE GENE ENVIRONMENT: child seeks environment or experience that supports genetic traits
Cell process of brain development
NEUROGENESIS: creation of new neurons from stem cells
CELL MIGRATION: migration of neurons from ventricular to sub ventricular zone to final home
SYNAPTOGENESIS: loss of synapse from lack of use or cell death
MYELINATION: formation of fatty sheath on neuronal axis to facilitate conduction of electrical signals
homozygous vs heterozygous
homozygous: same alleles expressed trait
heterozygous: different alleles for each gene
twins
monozygote: identical, zygote splits in 2 during 1st days of pregnancy, same chromosomes
dizygote: fraternal, 2 eggs released and fertilized by different sperm, unique set of chromosomes
number of neurons
- 14-16 billion neurons in adult cortex
- 61 billion glial cells
assembly of brain
- genome is blueprint for brain
- axons, dendrites, synapses are the wiring for electricity
when brain development happens
- most parental brain growth occurs within 3-4 years
- changing in myelination occur from 70-80 years
- neurulation happens from week 3-4
- differentiation of different areas in brain occur in fetus
differentiation of neural tube
- bottom 50% become spinal cord
- intermediate part becomes brain stem
- top part becomes brain
passive cell displacement
- new cells push old cells out
- short distances
- outside inside spatiotemporal organization
active neuronal migration
- long distances
- inside outside spatiotemporal organization
- know how to get there via glial cells
- neuron propels self along glial cell surface
- complete around 7 months
cell elaboration
- increase size and complexity of dendritic tree
- dendrites seen 15 weeks of gestations
- 1st synapses appear 23 weeks of gestations
synaptogenesis
- peak synaptic production occurs around 8 months
- peak differs by brain area though all reach peak by 2 years of age
- follows use it or lose it rule
visual cortex
shows earlier developmental landmarks than the frontal cortex such as in synaptic density
myelination and white matter
- grey matter is neurons themselves
- white matter is myelinated axons through which signals are transmitted (approx 50% of brain material)
- plays significant role in cognitive development
myelination
- critical for development and onset of many observable behaviours
- myelination in temporal cortex is related to language processing
- frontal areas related to IQ
myelination development
- beings in utero in peripheral areas (motor then sensory areas)
- 1st year: brain and cerebellum
- cortical areas start prenatally but show protracted myelination into early adulthood
- sensorimotor areas completed by 4 years
- parietal and temporal (language, attention, memory) by puberty
- prefrontal and frontal (working memory, reasoning, decision making) by early adulthood
neural development
- cell proliferation (fetus)
- cell migration (7 months)
- cell elaboration (culling, myelination)
brain stem
- basic attention
- reflexes (breathing, swallowing)
- balance
- arousal
- consciousness
- cardiac and respiratory functions
- information to and from body pass through brain stem on way to brain
cerebellum
- coordination of voluntary motor movement, balance, equilibrium, muscle tone
- possibly involved in memory
occipital lobe
- centre of processing visual information