Behavioral Genetics

Question 1

chromosome

Answer 1

strand of DNA molecules

humans have 46 in 23 pairs

Question 2

what determines which proteins are manufactured by a cell?

Answer 2

nucleotides

Question 3

cistron/exon

Answer 3

chain of nucleotides that code for one protein
humans have 20,000-100,000
1 would code 1 million neurons and 1 billion synapses

Question 4

what modulates what exons are coded for?

Answer 4

microRNAs

Question 5

monogenic trait

Answer 5

trait controlled by a single cistron variation

can be dominant (1 allele) or recessive (pair of alleles)

Question 6

heterozygous

Answer 6

different alleles

Question 7

homozygous

Answer 7

identical alleles

Question 8

PKU disease

Answer 8

excessive phenylalanine leads to development of phenylpyruvic acid, a developmental poison
onset can be prevented with an anti-phenylalanine diet

Question 9

pleiotropy problem

Answer 9

single human gene has many consequences

Question 10

types of mutant mice

Answer 10

knockout
knockdown
strengthen/modify

Question 11

how are transgenic mice made?

Answer 11

• molecular biology inserts new DNA into an embryonic stem cell
• stem cell is injected into an early mouse embryo; the resulting mice are chimeric
• chimeric mice breed; offspring are homozygous mutant, wildtupe, or heterozygous

Question 12

gene therapy

Answer 12

inserts new genes into neurons

Question 13

steps of gene therapy

Answer 13

• place gene DNA into a benign virus
• inject the virus into the brain
• virus splices a new DNA sequence into neuron chromosomes or nearby
• the neuron now makes a different protein

Question 14

optogenetics

Answer 14

DNA codes opsin photoreceptor molecule that twists in light

colored laser light in brain controls neuron activation

Question 15

human traits that are controlled by cistron genes

Answer 15

Huntington's disease
some forms of intersexuality
anxiety and depression 
schizophrenia
alcoholism 
male sexual orientation (?)

Question 16

IQ

Answer 16

polygenic trait

heritability = 0.5-0.8

Question 17

heritability

Answer 17

depends on mean and variance of the trait
measured from studying identical twins
is malleable
has strong predictive power for an original range of genes and environments
has unknown predictive power for new gene pools or environments
is 1 for dominant genes; variance mostly due to genetics
is 0 for variance mostly due to the environment

Question 18

neuron birth

Answer 18

embryo cells produce progenitor cells

genes determine which kind are made and for how long

Question 19

the tree cell layers that emerge in the gastrula

Answer 19

endoderm
mesoderm
ectoderm

Question 20

endoderm

Answer 20

controls development of the internal organs and gut lining

Question 21

mesoderm

Answer 21

controls development of muscles, circulatory system, and bones

Question 22

ectoderm

Answer 22

controls development of the epidermis and nervous system

Question 23

neurulation (day 18 of development)

Answer 23

ectoderm becomes the nervous system

formation of neural plate, neural tube, and neural groove

Question 24

when the is peak period of postnatal brain growth?

Answer 24

18-30 y.o.

Question 25

nerve growth factors (NGFs)

Answer 25

fertilize neuron growth

Question 26

sonic hedgehog protein

Answer 26

induces neurons in the spine

Question 27

cadherin and CAMs

Answer 27

cell adhesion molecules

Question 28

semaphorin

Answer 28

acts as a beacon for neuron growth

Question 29

cell death

Answer 29

regulated by the size of target which regulate the number of neurons and neurotrophic factors

Question 30

epigenesis

Answer 30

interaction with environment

Question 31

what switches genes on and off?

Answer 31

experiences

switching transcription