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1

Nature-Nurture

*Both heredity and environment shape human development, and interact in intricate ways
*Genes (nature) do nothing without environmental input (nurture)
*Environmental effects (nurture) are shaped by genetic constraints (nature)

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Epigenesis

*Process by which outside factors influence how hereditary material functions

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Coaction

*Reciprocal influence of hereditary and environmental facotrs

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Epigenetic model

Assumes that development is the result of interacting genetic and environmental elements, that these interactions are complex, and that they occur at multiple levels of functioning

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Sperm

23 chromosomes
*Male

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Ovum

woman's egg
*23 chromosomes

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Cytoplasm

*the ovum’s nucleus is surrounded by a great deal of cellular material
*Loaded with a vast array of chemicals

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Zygote

*23 pairs of chromosomes
-46 chromosomes
-22 matched pairs (autosomes)
-1 additional pair (sex chromosome, XX/XY)

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Autosomes

*22 of these pairs are matched
*The two chromosomes look and function alike

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Sex chromosomes

*23rd pair of chromosomes
*Sex determination
*Female zygotes: X chromosomes
*Male zygotes: X chromosome from their mothers; Y chromosome from their fathers

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Karyotypes

*one from a male and one from a female
*Displays the actual chromosomes from human body cells
*Chromosomes for a karyotype can be taken from cells anywhere in a person’s body

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Mitosis

*cell division process
*Produces two new cells each of which contains a duplicate set of chromosomes
*The new cells become eight cells, and so on.

13

Implantation

*attaching itself to the uterine lining
*Makes further growth and development possible
*Is now embryo

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Epigenome

full set of factors, from the cell to the outside world, that controls the expression of hereditary material

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Deoxyribonucleic acid (DNA)

*a remarkable organic chemical that made up the chromosomes in the nucleus of the cell
*Genes code for production of specific proteins
*The DNA code is a long sequence of molecules of four bases: adenine, cytosine, guanine, and thymine (A,C,G,T)

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Histones

long strands of DNA are combined with these proteins Wrapped and compacted to make up the chromosomes

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Genes

*functional units or sections of DNA
*“Coded” sections of DNA
*For each member of a pair of chromosomes, the number and location of genes are the same.
*Come in matched pairs, half from the mother (ovum) and half from the father (sperm)
*Provide a code that a cell is capable of “reading” and using to help construct a protein: a complex organic chemical, made up of smaller molecules called amino acids

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Transcription

*intertwined strands of DNA separate, and one of the strands acts as a template for the synthesis of a new, single strand of messenger ribonucleic acid or mRNA
*The sequence of bases (the “code”) is replicated in the mRNA
*Different sections of a gene’s code can be combined in different ways in the mRNA

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Translation

*the cell “reads” the mRNA code and produces a protoprotein, a substance that with a little tweaking can become protein.
*The cell can produce several protein variations from the same protoprotein
*Different cell climates (combinations of chemical) can induce different protein outcomes.

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Gene expression

*he entire transcription through translation process
*Whether or not genes will be expressed, and how often, is influenced by the environment of the cell.
*Most genes do not function full-time.
*Genes may be turned “on” in some cells and not in others

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Noncoded genes

how and when a gene’s code will be transcribed is partially regulated by sections of intergenic DNA

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Gene regulation

either initiate or prevent the gene’s transcription

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Transcription factors

*bind with the regulatory portions of the DNA, which initiates the uncoiling of the strands of DNA at the gene location
*Allows mRNA production to begin

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Receptor

transcription factor binds to one or only a few receptors -> bind to the regulatory DNA

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Methylation

*one epigenetic change that can affect the expression of a gene
*The addition of a methyl group (an organic molecule) to DNA, either to the coded gene or to regulatory DNA.
*Makes transcription of the gene more difficult
*May even turn off a gene for good
*Persistent
*Is passed on when chromosomes duplicate during cell division
* tighter binding and reduces gene transcription

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Demethylation

*methyl groups may detech from DNA
-Gene transcription is likely to increase
*looser binding and more transcription

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Acetylation

loosens the binding, typically increasing gene transcription

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Deacetylation

tighten the bonds again

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Cross-fostering studies

they gave the offspring of high LG mothers to low LG mothers to rear, and they gave the offspring of low LG mothers to high LG mothers to rear.

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Genotype

the full complement of an organism’s genes

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Phenotypes

physical and behavioral traits

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Dizygotic twins/fraternal twins

are conceived when a mother releases two ova in the same menstrual cycle, and each ovum is fertilized by a separate sperm
*Develop from two separate zygotes
*Share about 50% of their genes on average

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Concordance

similarity between members of a pair of twins

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Disconcordance

differences between members of a pair of twins

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Alleles

*slightly different varieties of genes at the same location or locus on the chromosome
*Genotypes

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Dominant-recessive relationship

two alleles of the same gene with only the first affecting the phenotype

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Carrier

* of a recessive gene
*“Surface” in the phenotype of one of his offspring
*If a child receives two recessive allels, one from each parent, the child will have the recessive trait.

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Codominance

*Two different alleles producing a blended or additive outcome
*Type AB blood

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Polygenic

*make the prediction of traits from one generation to another very difficult
*Any one pair of gene alleles has only a modest influence on phenotypic outcomes

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Genomic imprinting

*a special example of how methylation can change outcomes

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Typical Development

*Prenatal development is orderly and continuous progress from a single fertilized cell to a highly differentiated organism
*Period of the zygote: about 2 weeks
-From fertilization to implantation
*Period of the embryo: from about the 3rd to 8th week
-When most of the body’s organ systems and structures are forming
*Period of the fetus: from the 9th week until birth
-When the reproductive system forms, gains in body weight occur, and the brain and nervous system continue to develop dramatically.

42

Hereditary diseases

Can occur as a function of defective genes, wrong number of chromosomes

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Sickle-cell anemia

*the red blood cells are abnormally shaped, more like a half moon than the usual, round shape.
*The abnormal cells are not as efficient as normal cells in carrying oxygen to the tissues.
*Breathing problems
*Organ malfunctions and without treatment, to early death
*A recessive gene allele causes the malformed blood cells

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Teratogens

Environmental agents that harm the fetus
-Timing and dosage of exposure critical

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Inadequate nutrition

Lacking adequate protein, vitamins, and minerals for development

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Genetic counselors

*help screen candidates for such testing, as well as provide information and support to prospective parents, helping them to understand genetic processes and cope with the choices that confront them-choices about testing, childbearing, and parenting

47

Mutation

*when these alleles occur in some future generation
*A change in the chemical structure of an existing gene
*Occur spontaneously
*Due to environmental influences

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Progeria

*fatal disorder that causes rapid aging, so that by late childhood its victims are dying of “old age”
*Is caused by a genetic mutation during the embryonic period of prenatal development

49

Hungtinton's disease

*the nervous system to deteriorate, usually beginning between 30 and 40 years of age.
*Uncontrolled movements and increasingly disordered psychological functioning- ending in death
*Test
*No cure

50

Down syndrome (trisomy 21)

*An extra copy of chromosome number 21
Mental retardation
*The increased risk with parental age holds only for mothers

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Kwashiorkor

*children who suffer severe protein and calorie shortages at any age.
*Stunted growth
*A protuberant belly
*Extreme apathy
*Therapeutic dies can eliminate the apathy of kwashiorkor, but cognitive impairments are likely to persist.

52

Fetal alcohol syndrome (FAS)

*babies who are exposed to alcohol prenatally
*Virtue of their unique facial configuration
*Growth retardation, either pre-or postnatally, both in weight and length
*Many organ systems can be affected
*The central nervous system
*Mental retardation and behavior problems

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Fetal alcohol effects (FAE)

*children exposed to smaller amounts of alcohol prenatally
*Significant learning impairments
*The absence of physical symptoms or structural malformations
*Cognitive limitations

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Neurulation

*cells from the embryo’s upper surface began to form a sheet that rearranged itself by turning inward and curling into a neural tube
*at 2 weeks, around 25th day the first neurons form

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Formation of major structures of the brain

*Hindbrain: medulla, pons, cerebellum, and reticular formation, regulate autonomic functions
*Midbrain: superior colliculi, inferior colliculi, and substantia nigra, involved in vision, hearing, and consciousness
*Forebrain: cerebrum, thalamus, hypothalamus, and limbic system, handles neural communication

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Neuron

*cells from the interior surface of the neural tube
*Nerve cells
*Become the building blocks of your brain
*Cell body, containing the nucleus
*Dendrites: short extensions, receive impulses
*Axon: long extension, transmits impulses
*Axon terminals: stores and releases neurotransmitters to transmit signals across the synapse, the gap between neurons

57

Glial cells

*your neurons began to migrate outward from their place of birth rather like filaments extending from the neural tube to various sites in your still incomplete brain
*Supporting cells
*Stretching from the inside of the neural tube to its outside, provided a type of scaffolding for your neurons, guiding them as they ventured out on their way to their final destinations

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Cerebral cortex of forebrain

developed last migrated the farthest

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Nucleus

a cluster of cells creating a structure, rather than to the kind of nucleus that is found in a single cell

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Lateralization

*hemispheric specialization
*The left hemisphere controls functioning of the right side of the body and vice versa- language functions,
*Visual-spatial skills- right

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Occipital lobe

*located at the back of the head
*Handles visual information

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Temporal lobe

*the sides of each hemisphere- auditory processing

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Parietal lobe

*top of each hemisphere, behind a fissure called the central sulcus- processing of somatosensory information

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Frontal lobe

situated at the top front part of each hemisphere, controls voluntary muscles movements and higher level cognitive functions

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Prefrontal cortex (PFC)

part of the frontal lobe that occupies the front or anterior portion; sustained attention, working memory, planning, decision regulation- moderate an overactive amygdala as well as the activity of the HPA axis

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Anterior cingulate cortex (ACC)

in the middle of the brain above the corpus callosum; mediates cognition and affect

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Myelination

if the message is to fire, the speed of the resulting electrical impulse is increased when glial cells wrap themselves around the axon, thus facilitating conduction

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White matter

*bundles of myelinated axons
*The peak of white matter volume occurs around age 50

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Grey matter

bundles: bundles of cell bodies, dendrites, and unmyelinated neurons

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Circuits

they are joined via their synaptic connections into groups

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Projection neurons

have axons that extend far away from the cell body

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Interneurons

branch out closer to the local area

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Synapses

new connections among neurons

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Synaptogenesis

the generation of synapses, took place after birth, when much more sensory stiulation became available

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Neural pruning

many neurons would die off and many synaptic connections would be selectively discarded.

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Synaptic overproduction

occurs when it is highly likely that nature will provide the appropriate experience to structure the development of a particular system

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Experience-expectant

it is experience that is part of the evolutionary history of the organism and that occurs reliably in most situations

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Experience-dependent

quality of the synaptic growth “depends” upon variations in environmental opportunities

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Homeostasis

*adaptation to stress
*The body’s capacity to regulate internal physiology primarily through systems that exert reciprocal control
*Maintaine internal balance
*Reflexive, physiological feedback loops, primarily controlled by lower-level brain areas, that balance internal systems around a fixed set-point

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Stress

a nonspecific response to any demand

81

General adptation syndrome (GAS)

* a generic way that organisms responded to threats to their well-being
*Alarm phase, when a threat is first recognized and when the body prepares for flight or fight
*Resistance phase, the body’s stress response is active as it continues to resist the effects of the stressor
*Exhaustion, if the struggle persists to the point of complete resource depletion
*Depression, illness, or even death can occur after severe, prolonged stress

82

Allostasis

*central nervous system (CNS) control over multiple interacting regulatory processes maintains “balance through adaptation”
*Allows for adjustments to be made within a range of possibilities across a variety of systems to suit the circumstances.
*Instead of retuning to a fixed set point, the best balance for each specific challenge is found- allostatic accommodation
*Nervous, immune, and endocrine systems are the primarily interconnected networks that mediate this adaptive response

83

Hypothalamic-pituitary-adrenal (HPA) axis

* activating (amygdala) or inhibiting (hippocampus)
*Major stress managing apparatus
*Hypothalamus communicates the danger message to pituitary gland by chemical messenger corticotropin releasing factor (CRF) -> pituitary gland release adrenocorticotropic hormone (ACTH) into the bloodstream
-Both CRF and ACTH production: permanently affected by early trauma
-Abormalities- later depression
-The early experience of stress - lifetime disadvantage, rendering the individual sensitized to stress by means of altered functioning of the HPA axis
-ACTH -> adrenal glands: situated atop the kidneys, receive the message to release the message to release cortisol

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Allostatic load

*wear and tear of chronic stress
*Overload
*Cost of accommodation
*Cumulative burden on systems that need to adjust constantly to psychological or environmental demands

85

Sympathetic nervous system (SNS)

releases important chemicals such as epinephrine (adrenaline) and norepinephrine (noradrenalin) that send a burst of energy to those organs necessary for fight or flight while diverting energy from less necessary systems.

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Parasympathetic nervous system (PNS)

counteracts the sympathetic system’s effects and down-regulates its activity once the threat has passed.

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Cortisol

*glucocorticoid hormone produced by humans
*Stress hormones
*Travel back to the brain
*Bind to receptors on the amygdala and the hippocampus
*Sufficient glucocorticoid receptors exist to terminate the system effectively
*Inadequate system of glucocorticoid receptors- hyperctive stress system

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Atypical depression

blunted cortisol functions

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Melancholic depression

elevated cortisol levels

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Cytokines

*chemical messengers of the immune system
*Are produced during the immune response
*Can be either pro-inflammatory or anti-inflammatory
*Inflammation: body’s protective response to infection or injury
-When appropriate, inflammation is adaptive
-When inflammatory processes persist unremittingly, mental and physical diseases can result
*Overproduction of pro-inflammatory cytokines -> depression and other mood disorders
*Pass through the blood-brain barrier to affect brain areas related to emotion

91

Dose-response relationship

* between numbers of prenatal stressors and later maladaptive outcomes
*Lower levels of stressors predicted lower symptoms levels
*Symptoms increased with each additional stressor exposure