Chapter 2 Flashcards
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)
Epigenesis
*Process by which outside factors influence how hereditary material functions
Coaction
*Reciprocal influence of hereditary and environmental facotrs
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
Sperm
23 chromosomes
*Male
Ovum
woman’s egg
*23 chromosomes
Cytoplasm
- the ovum’s nucleus is surrounded by a great deal of cellular material
- Loaded with a vast array of chemicals
Zygote
- 23 pairs of chromosomes
- 46 chromosomes
- 22 matched pairs (autosomes)
- 1 additional pair (sex chromosome, XX/XY)
Autosomes
- 22 of these pairs are matched
* The two chromosomes look and function alike
Sex chromosomes
- 23rd pair of chromosomes
- Sex determination
- Female zygotes: X chromosomes
- Male zygotes: X chromosome from their mothers; Y chromosome from their fathers
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
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.
Implantation
- attaching itself to the uterine lining
- Makes further growth and development possible
- Is now embryo
Epigenome
full set of factors, from the cell to the outside world, that controls the expression of hereditary material
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)
Histones
long strands of DNA are combined with these proteins Wrapped and compacted to make up the chromosomes
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
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
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.
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
Noncoded genes
how and when a gene’s code will be transcribed is partially regulated by sections of intergenic DNA
Gene regulation
either initiate or prevent the gene’s transcription
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
Receptor
transcription factor binds to one or only a few receptors -> bind to the regulatory DNA
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
Demethylation
- methyl groups may detech from DNA
- Gene transcription is likely to increase
- looser binding and more transcription
Acetylation
loosens the binding, typically increasing gene transcription
Deacetylation
tighten the bonds again
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.
Genotype
the full complement of an organism’s genes
Phenotypes
physical and behavioral traits
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
Concordance
similarity between members of a pair of twins
Disconcordance
differences between members of a pair of twins
Alleles
- slightly different varieties of genes at the same location or locus on the chromosome
- Genotypes
Dominant-recessive relationship
two alleles of the same gene with only the first affecting the phenotype
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.
Codominance
- Two different alleles producing a blended or additive outcome
- Type AB blood
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
Genomic imprinting
*a special example of how methylation can change outcomes
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.
Hereditary diseases
Can occur as a function of defective genes, wrong number of chromosomes
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
Teratogens
Environmental agents that harm the fetus
-Timing and dosage of exposure critical
Inadequate nutrition
Lacking adequate protein, vitamins, and minerals for development
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
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
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
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
Down syndrome (trisomy 21)
*An extra copy of chromosome number 21
Mental retardation
*The increased risk with parental age holds only for mothers
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.
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
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
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
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
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
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
Cerebral cortex of forebrain
developed last migrated the farthest
Nucleus
a cluster of cells creating a structure, rather than to the kind of nucleus that is found in a single cell
Lateralization
- hemispheric specialization
- The left hemisphere controls functioning of the right side of the body and vice versa- language functions,
- Visual-spatial skills- right
Occipital lobe
- located at the back of the head
* Handles visual information
Temporal lobe
*the sides of each hemisphere- auditory processing
Parietal lobe
*top of each hemisphere, behind a fissure called the central sulcus- processing of somatosensory information
Frontal lobe
situated at the top front part of each hemisphere, controls voluntary muscles movements and higher level cognitive functions
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
Anterior cingulate cortex (ACC)
in the middle of the brain above the corpus callosum; mediates cognition and affect
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
White matter
- bundles of myelinated axons
* The peak of white matter volume occurs around age 50
Grey matter
bundles: bundles of cell bodies, dendrites, and unmyelinated neurons
Circuits
they are joined via their synaptic connections into groups
Projection neurons
have axons that extend far away from the cell body
Interneurons
branch out closer to the local area
Synapses
new connections among neurons
Synaptogenesis
the generation of synapses, took place after birth, when much more sensory stiulation became available
Neural pruning
many neurons would die off and many synaptic connections would be selectively discarded.
Synaptic overproduction
occurs when it is highly likely that nature will provide the appropriate experience to structure the development of a particular system
Experience-expectant
it is experience that is part of the evolutionary history of the organism and that occurs reliably in most situations
Experience-dependent
quality of the synaptic growth “depends” upon variations in environmental opportunities
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
Stress
a nonspecific response to any demand
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
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
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
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
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.
Parasympathetic nervous system (PNS)
counteracts the sympathetic system’s effects and down-regulates its activity once the threat has passed.
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
Atypical depression
blunted cortisol functions
Melancholic depression
elevated cortisol levels
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
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
