b&b ch4: genetics, development, and plasticity

why is the brains anatomy is plastic

it continues changing throughout life

these are the units of heredity that maintain their structural identity from one generation to another

genes

most genes come in pairs of this because they are aligned along them in strands of genes that come in pairs

chromosomes

a gene has been defined as part of a chromosome, which is composed of the double strand molecule

deoxyribonucleic acid (DNA)

this is a single strand chemical, a strand of DNA serves as a template model for the synthesis of this

ribonucleic acid (RNA)

what are the four based of DNA

adenine, guanine, cytosine, and thymine

what are the four bases of RNA

adenine, guanine, cytosine, and uracil

what does the order of DNA based determine for RNA

the order of corresponding bases along an RNA

what does the order of bases along an RNA molecule determine

the order of amino acids that compose a protein

if three RNA bases are in order cytosine, adenine, and guanine, then the protein adds the amino acid __

glutamate

if the next three RNA bases are uracil, guanine, and guanine, then the next amino acid is ___

tryptophan

any protein consists of some combination of ___

20 amino acids

if you have the same gene on two chromosomes, you are ___ for that gene

homozygous

if you have an unmatched pair of genes, you are ___ for that gene

heterozygous

a ___ gene exerts a strong effect in either the homozygous or heterozygous condition

dominant

a ___ gene exerts its effect only in the homozygous condition

recessive

what gene occurs when neither allele from the parents is fully dominant over the other

intermediate gene

the genes on the sex chromosomes (designed X and Y in mammals) are known as ___

sex-linked genes

these genes are any numbered chromosome that is not a sex chromosome

autosomal genes

what has the sites that influence the functioning of genes on other chromosomes

small Y chromosome

these genes are present in both sexes, but active mainly in one sex

sex-limited genes

if sex limited genes are present in both sexes but active mainly in one, what activates it and when are their effects shown

sex hormones; in puberty

what is described as a heritable change in a DNA molecule

a mutation

what does changing a DNA base to any of the three types mean

that the mutant gene will code for a protein with a different amino acid at one location in the molecule

most mutations are harmful, except when ___

the environment changes

another way to change genes is by ___, but most cases are harmful

duplication or deletion

because ___ provide new material for genetic change, they have been a necessary part of our evolutionary history

microduplications

the field of ___ deals with changes in gene expression

epigenetics

for psychology, the important aspect of epigenetic is that___

experiences can produce epigenetic changes, altering gene expression in the brain

what binds DNA into a shape that is more like string wound around balls

proteins called histones

how does a gene activate

DNA must partially unwind from the histones

what does adding an acetyl group to a histone tail do

loosens the histones grip on the DNA, facilitating the expression of genes

what does removing an acetyl group do to a histone

tightens the histones grip on the DNA and silences the gene

what does the epigenetic change of adding a methyl group at the beginning of a gene do

turns the gene off

what does the epigenetic change of removing a methyl group at the beginning of a gene do

turns the gene on

how far in can epigenetic changes be inherited

at least for a generation or two

severe traumatic experiences in early childhood decrease ___, increasing the later risk of depression or posttraumatic stress disorser

methylation of many brain genes

this describes the ranges from zero, indicating no genetic contribution to the variation, to one, indicating complete control

heritability

twins from one fertilized egg are called___

monozygotic

twins from two fertilized eggs are called ___

dizygotic

what is about the only behavior that has not shown a significant heritibility

religious affiliation

this study tests a hypothesis such as “a gene that increases the activity of the serotonin transporter may be linked to an increased risk of depression”

candidate gene approach

this study examines the entire set of chromosomes while comparing two groups, such as people with and without depression

genome wide association study

what is phenylketonuria (PKU)

a genetic inability to metabolize the amino acid phenylaline

what happens if PKU is not treated

the phenylalanine accumulates to toxic levels, impairing brain development and leaving a child cognitively impaired, restless, and irritable

although PKU is a hereditary condition, what can modify it

environmental interventions such as a specific diet

what does the PKU diet consist of avoiding

meats, eggs, dairy products, grains, and aspartame (50% phenylalanine)

this is the change over generations in the frequencies of various genes in a population

evolution

what is the term that charles darwin preferred that emphasized the idea of changes without necessarily implying improvement

descent with modification

what are the two questions about evolution

how did some species evolve, and how do species evolve

to ask how a species did evolve is to ask ___

what evolved from what

the question of how species do evolve is a question of __

how the process works, and that process is necessary outcome from what we know about reproduction

this is choosing individuals with a desired trait and make them the parents of the next generation through a process called ___

artificial selection

this is the discredited hypothesis that the use or disuse of some body part will increase or decrease its size in the next generation, known as “inheritance of acquired characterisitcs”

lamarckian evolution

this is the spreading of genes; the number of copies of ones genes that endure in later generations

fitness

does evolution benefit the individual or the species

neither: it benefits the genes, your genes use you to reproduce themselves

this concerns how behaviors evolved and emphasizes evolutionary and functional explanations

evolutionary psychology

this is how our genes reflect those of our ancestors and why natural selection might have favored genes that promote certain behaviors, any behavior characterisitc of a species must have provided an advantage at least in ancesteral times

evolutionary psychology

this is an action that benefits someone other than the actor

altruistic behavior

how does a gene spread

only if the individuals with it reproduce more than those without it

this is the selection for a gene that benefits the individuals relatives

kin selection

this is the idea that individuals help those who will probably return the favor

reciprocal altruism

this is favoring a gene becuase of its benefits to a group; altruistic groups thrive better than less cooperative ones

group selection

what is a series of genes found in vertebrates,that regulate the expression of other genes and control the start of anatomical development, including which end is the front and which is the rear

homeobox genes

all homeobox genes share a large sequence of DNA bases, in human, what have mutations been linked to

serious mental and physical disorders

this is the production of new cells

proliferation

in early development, what do the cells lining the ventricles of the brain do

divide

what are the cells that remain where they are, continuing to divide

stem cells

in early development, what do primitive cells that are not identifiable as neurons or glia do

migrate

what guides neuron migration

the chemicals immunoglobins and chemokines

what causes impaired migration, decreased brain size, and intellectual impairment

deficits in immunoglobulins and chemokines

what does a cell do as it differentiates into a neuron

begins to form its dendrites, axon, and synapses

how do neurons develop different anatomies and functions

based on when and where they developed and what genes they express

what is the formation of synapses, begins long before birth and continues throughout life, as neurons form new synapses and discard old ones

synaptogenesis

this is the slower stage of neuronal development, the process by which glia produce the insulating fatty sheaths that accelerate transmission in many vertebrate axons

myelination

forms in the spinal cord, then hindbrain, midbrain, and forebrain, continues gradually throughout life and is modified by certain types of learning

myelin

neurons can modify their shape, but the brain can’t develop new neurons, what is the exception and why

olfactory receptors, one cell remains immature while the other differentiates to replace a dying olfactory receptor

how could researchers determine whether new neurons form in the adult human brain

radioactove isotope of carbon, 14C

with 14C, how can u tell the age of something such as tree rings

every cell acquires DNA molecules when it forms and keeps them until it dies

with the test of 14C on skill cells, how old are they

less than a year old, they turn over rapidly

with the test of 14C on skeletal muscles, how old are they

15 years old

with the test of 14C how old are heart cells

as old as the person, no more than 1 percent replaced per year

with a 14C test, how often does the cerebral cortex form new neurons

none formed after the year of birth

how is the hippocampus kept young for learning new tasks in mammals

small interneurons form throughout life

in humans, when can new neurons be found in the hippocampus

up to age 7

what is neural darwinism

competition among axons

what does each ganglion of the sympathetic nervous system have enough of

axons to supply all muscles and glands in its area, with none left over

when any of the sympathetic nervous systems neurons forms a synapse into a muscle, what does the muscle deliver

a protein called nerve growth factor (NGF)

what does does nerve growth factor do

promotes the survival and growth of the axon

what does an axon that does not receive NGF do if itd axon dpes not connect to an appropriate postsynaptic cell by a certain age

degenerates and its cell body dies

what is the process called that the neuron kills itself

apoptosis

what cancels the plan for apoptosis

NGF

what indicates maturation when an area of the developing nervous system makes more neurons that will survive into adulthood

loss of cells

NGF that is a chemical that promotes the survival and activity of neurons, a

neurotrophin

in addition to NGF, the nervous system responds to this and several other neurotrophins

brain-derived neurotropic factor

this is essential for growth of axons and dendrites, formation of new synapses, and learning

neurotrophins