Week 2 - Chapter 3 Flashcards
Genome
complete set of DNA of an organism (+/- 20.0 protein coding genes)
genotype
the inherited genetic material of an individual
phenotype
the expression of the genotype that is visible and observable
- includes both body characteristics as behavior
environment
every aspect of individuals and their surroundings other than genes -
so also prenatal influences (chapter 2 Siegler)
five important relations
- parents genotype - child’s genotype
- childs genotype - childs phenotype
- childs environment - childs phenotype
- childs phenotype - childs environment
5.child’s environmentt - child genotype
chromosones
molecules made of DNA - 2 twisted strands
gene
segment of DNA that codes for a protein
alleles
different forms of a gene
Heredity
number of chromosomes in each body cell
46, 23 pairs
gametes (sperm etc) number of chromosomes
23
zygote (offspring)
46 chromosomes (mix of genetic material sperm and egg cell)
karyotype
individual complete set of chromosomes
random assortment
occurring during meiosis
- random chance of what one will end up in egg or sperm cell
crossing over
occurring during meiosis
‘swap’ of DNA sections during meiosis
mutations
change in a section of DNA
- random/spontaneous
- environmental influences
*In most cases, harmful
3 ways genetic variation occurs
random assortment
mutation
crossing over
endophenotype
in between steps
- measurable characteristics of the pathway from genotype to phenotype
regulator genes
genes impact development if they are turned on at the right time/in the right position in the body/ the right time period
on/off - > diversity in gene expression
(increase diversity in gene expression)
genes work in a __ effect to achieve outcome
cascade
* can be impacted by enviormental influences
thalidomide drug *gene effect
- drug prescribed in 60’s to pregnant women suffering from morning sickness
- didn’t realize it would effect development of embryo
thalidomide drug effect
impact on the development of limbs (how the genes were expressed)
- leading to children born with only part of limbs
alleles
different forms of a gene
- dominant (Dd) vs recessive (dd)
- homozygous vs heterozygous
polygenic inheritance
most traits, a combination of traits (complex!)
x linked disorders
only affect males
women are only carriers, never come to expression
phenylketonuria (PKU)
- individuals homozygous for defect recessive gene on chromosome 12 - unable to metabolize phenylaline (AA in food)
phenylketonuria (PKU) effect
- severe consequences, impaired brain development and intellectual disabilities
-rare but dangers inherited disorder
phenylketonuria (PKU) screening
- early detection by screen of newborns
- treatment with diet (influence environment, genotype is not expressed in phenotype)
- damage can be avoided
MAOA Gene
agression gene
- low or high activity in people
- effects of this genotype are dependant on environmental influences
3 examples of genes of how genotype and environment interact
MAOA gene
phenylketonuria (PKU)
direct environment
MAOA Gene effect
mild childhood maltreatment
: low anti-social
high amount childhood maltreatment:
highly anti-social
Parental contribution to the child’s environment
- what they do
- by there own genetic background - even alleles that are not passed on to the child influence the development of the child
ie: mom likes reading, child is more likely to enjoy reading
child’s phenotype -> childs environment
active
1. temperament
outgoing/shy
- interest and personalities
playmates/activities
childs environment -> childs genotype
expression of a genotype is not fixed (epigenetics)
epigenetic
changes in a gene expression mediated by the environment
how does epigenetic occurs
methylation:
- methyl molecules bind to DNA
*block transcription
*no protein production
- effects can last long and be passed on to offspring
how does the combination of genetic and environmental factors influence traits
- behaviour
- development
heritable
characteristics or traits that are genetically transmitted
family study design
twin - study
adoption study
adoptive twin study
twin study
identical vs fraternal
- equal environment assumption?
how they are treated by environment
adoption study
adopted children
* not biological parents
- environmental effects on genetics
adoptive study example
identical twin firefighters: split at birth
*appeared to share lots of characteristics showed based on genetic material
genetic influences on brain structure (Paul Thomson paper)
compared fraternal and identical twins
how genetic and environmental influences lead to expression of different traits: bran structure
genetic influences on brain structure (Paul Thomson paper) results
regions of the bran which are under genetic control while other regions are shaped by environmental influences
heritability
statistical estimate of the proportion of the measured variance on a trait among ind in a given population that is attributable to genetic differences across those individuals
intelligence is heritable mean?
heritability estimates apply only to a particular population living in a particular environment
can heritability of intelligence change?
yes, it can change as a function of developmental factors
- increases with age
WEIRD SAMPLE
(white– educated– industrialized– rich– democratic)
*need to include a wider population to have a more reliable estimate
GWAS
method that links DNA segments to specific traits
- combo of many genes underlies a heritable trait
T OR F
A low heredibility estimate indicates that a phenotype is not determine by a genetic code
F - Means that the trait is influenced more by environmental factors than genetic ones. However, it doesn’t mean that the trait is not influenced by genes
T OR F
A highly heritable traits constantly expressed over the lifespan
Highly heritable traits are influenced by genetic factors, but their expression can still change during different stages of development or in response to environmental factors.
neuron
nerve cel, the basic unit of information processing within the brain and between the brain and other parts of the brain
*constitues the gray matter of the brain
3 components of the neuron
Cell body: contains the nucleus and is responsible for maintaining the cell’s functions.
Dendrites: Dendrites receive signals from other neurons and transmit them toward the cell body.
Axon: transmits electrical impulses away from the cell body to other neurons or muscles.
synapse
small space between axon terminal of one neuron and dendrite of another neuron -> info processing
glial cells forms myelin sheath
increase the speed and efficiency of information processing
*role in protection and regeneration
cerebral cortex
the gray matter of the brain, with 4 lobes associated with a specific set of behavioral characteristics
frontal lobe
working memory cognitive control
pariteal lobe
spatial processing
integration of sensory
information
temporal lobe
speech and language
music
emotional information
occipital lobe
processing visual information
cerebral cortex:
consists of two hemispheres connected by corpus callosum
cerebral lateralization
specialization; emerges already in early in development
cerebellum
small brain
- role in coordinating voluntary movements, balance, and motor skills, as well as fine-tuning motor control and facilitating learning of motor tasks.
neurogenesis
proliferation of neurons (production of new cells)
- through cell division
- starts 42 days after conception (100 billion neurons)
- also in adulthood - influenced by environment (experiences)
cell differentiation: arborization
formation of new dendritic trees and branches
formation of spines: increase capacity to connect
cell migration is supported by what cell?
glial cells
myelination of axons leads to?
‘white matter’
- speed up info processing
differential timing
gray matter replaced by white mature
*different timing for different parts of the brain (regions of brain mature at different times)
Synaptogenesis
formation of synapses between neurons -> trillion connections
Synapse elimination
synaptic pruning based on activity (like white matter); differential timing over bran regions
*synapses not being used are eliminated (differential timing - based on experience)
synaptic pruning go wrong?
yes
- emergence of schizophrenia and autism ASD
- high activity
- synapses that are useful are being pruned
plasticity
capacity of the brain to be affected by experience
provides flexibility and less info needs to be genetically encoded
allows for recovery of damaged areas (although not always): children > adults
experience expectant processes
normal wiring of the brain resulting from specific typical experiences
*EXPECT
- flexible but vulnerable
experience expectant processes - sensitive?
sensitive periods where the brain is sensitive to receiving information
experience expectant processes - how is it vulnerable
if a certain stimulus is not present, a certain function will not develop.. can lead to irreversible damage
ie: reading
Experience-dependent processes:
creation and reorganization of neural connections as a function of an individual’s experiences (not necessarily shared with others)
Experience-dependent processes: example
training can shape the brain
ie: sports or musician lead to plastic changes in the brain
Example of experience-dependent plasticity
TAXI
looked at gray matter
- related to months working as a taxi driver
- larger gray matter in posterior hippocampus (spatial navigation) for those who have driven longer
T OR F
Plasticity is only present prenatally and in childhood
F : more plastic in childhood, but still happens in adulthood
T OR F
Plasticity makes the brain flexible but also vulnerable to environmental influences
T
