Module 3

Question 1

DNA

Answer 1

2 strands of a sequence of 4 chemical bases (ATCG)
- bases on one strand pair with complementary bases on other

Question 2

genes

Answer 2

• sections of DNA that code for specific proteins
  
  • about 20,000 different genes
  • only -1% of our total DNA

Question 3

regulatory DNA regulates genes

Answer 3

switch on and off throughout life
- some on/off built in, but some can be influenced by environment (thalidomide)
- on/ off can malfunction, creating regulator-gene defects

Question 4

chromosomes

Answer 4

contain our DNA, 23 pairs
- 22 pairs of autosomes
- 1 pair are sex chromosomes- y much smaller (fewer genes): contains gene that sets in motion processes for creating males

Question 5

random assortment

Answer 5

during meiosis one of each of the 23 pairs of chromosomes randomly goes to new egg or sperm- en up with new combinations of chromosomes in offspring
- diversity at the level of whole chromosomes

Question 6

crossing over

Answer 6

during meiosis two member of a pair of chromosomes sometimes swap sections of DNA to random assortment
- diversity within chromosomes

Question 7

mutations

Answer 7

random changes in DNA
- mostly bad, so often die out

Question 8

alleles

Answer 8

different variants of the same gene that we inherit from each of our parents (one on each chromosome)
- only about 1/3 of genes have these
- the gene for eye color can have different alleles (brown, blue, green)
- blood types are alleles
- we can be homozygous or heterozygous
- if heterozygous, dominant allele is expressed over recessive (e.g. your brown eye-color alleles are BrBl)
- recessive: only affected if you inherit gene from both parents
- dominant: affected if you inherit gene from one parents
- fun fact: green eye color is recessive to brown, but dominant to blue

Question 9

co-dominant and incomplete dominance

Answer 9

• codominant alleles= both expressed (AB blood)
• incomplete dominance alleles= blend of alleles (hair shape)

Question 10

genotype vs. phenotype

Answer 10

• genotype is your genetic information (genes, particular alleles)
• phenotype is the way your genetic info is expressed
  
  • your actual outcomes: eye color, height, IQ, personality, and everything else
  • influenced by environment

Question 11

norm of reaction

Answer 11

• all the phenotypes that could theoretically occur from given genotype across all possible environments

Question 12

gene-environmental interaction

Answer 12

• one’s genes make them particularly sensitive or susceptible to particular environments
  
  • e.g., phenylketonuria (PKU): genetic inability to metabolize amino acid phenylalanine
    
    • causes severe mental retardation
    • with a strict diet, you’re fine

Question 13

methylation

Answer 13

methyl molecule binds to DNA; impacts typically reduces gene expression

• more methylation= less stress regulation= bad

Question 14

heritability

Answer 14

variability in a trait in the population that is attributable to genes
- differs across populations who may have greater or lower environmental impact

Question 15

genetic influence on developmental outcomes (like cognitive abilities) ….

Answer 15

increases over time!
- why?
- 1. new genetic effects as maturation unfolds
- for instance, genes that are only active during puberty
- 2. genetic tendency to seek out particular environments magnifies effects of genetic differences

Question 16

two kinds of environmental influences

Answer 16

• shared = how the environment makes you more like your siblings (SES, school, etc)
• non-shared = how the environment makes you unlike your siblings (anything that happens to you but not your siblings)
  
  • as you age, you experience more and more non-shared environment

Question 17

phenotype is the results of

Answer 17

genetics+ how the environment makes you the same + how the environment makes you different

Question 18

parts of a neuron

Answer 18

• cell body: contains basic biological material that keeps neuron functioning
• dendrites: receive input from other cells and conducts toward the cell body
• axon: conducts electrical signals to connections with other neurons

Question 19

synaptogenesis

Answer 19

connections between neurons formed btw dendrites and axon terminals

Question 20

apoptosis (cell death) and synaptic pruning

Answer 20

• way to many connections at first
  
  • cell death and elimination of unneeded/ unused connections
  • neurons that fire together, wire together
    
    • neural darwinism
  • problems with pruning linked to diseases like autism (too little) and schizophrenia (too much)

Question 21

experience-expectant plasticity

Answer 21

reasonably typical environment will fine-tune neural circuitry in a normal way, makes us largely similar to each other
- visual system: just need to see some things
- efficient! means fewer genes can be devoted to normal development
- but also vulnerable to aberrant input
- strabismus and other visual issues need correcting early or brain will permanently reorganize (timing matters)
- if normal experience is lacking, or if brain injury occurs, all is not lost, the brain can often reorganize and compensate:
- deaf individuals have language areas tuned to visual info
- blind individuals show activation in visual areas when reading braille

Question 22

experience-dependent plasticity

Answer 22

brain development as a function of individual experience
- not what everyone tends to experience
- violinists, braille readers have increased cortical space dedicated to fingers
- dyslexia therapy can change your brain
- rats growing in impoverished, normal, or complex environments

Question 23

low SES infants have

Answer 23

• smaller brain volumes
  
  • thinner cortices
  • lower ERP power