Developmental and Research Designs

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8Developmental & Research Designs
* Human development - the scientific study of the changes that occur in people as they age from conception until death. * How is human development studied?
* Longitudinal design - research design in which one participant or group of participants is studied over a long period of time. * Cross-sectional design - research design in which several different age groups of participants are studied at one particular point in time. * Cross-sequential design - research design in which participants are first studied by means of a cross-sectional design but also followed and assessed for a period of no more than six years. Nature vs. Nurture

* Nature - the influence of our inherited characteristics on our personality, physical growth, intellectual growth, and social interactions. * Nurture - the influence of the environment on personality, physical growth, intellectual growth, and social interactions. * Behavioral genetics – study that focuses on nature vs. nurture. The Beginnings of Human Life

* Genetics - the science of inherited traits
* Human life begins as a single cell which eventually evolves into about 50 to 100 trillion multiple cells. * The nucleus (control center) of each cell contains structures called chromosomes . Each chromosome is made up of DNA (deoxyribonucleic acid) and protein. DNA contains tiny segments called genes that we inherit from our parents.
Genetics & Development
* Chromosome - tightly wound threadlike strands of genetic material that stores (DNA) and transmits (genes) genetic information. * DNA (deoxyribonucleic acid) - special molecule that contains the genetic material of living organisms. It stores genetic information. * Gene - section of DNA having the same arrangement of chemical elements. It transmits genetic information. * Dominant - referring to a gene that actively controls the expression of a trait. * Recessive - referring to a gene that only influences the expression of a trait when paired with an identical gene. Gene Linked Abnormalities

Abnormalities can be produced by mutated chromosomes and harmful genes. There are more than 7,000 genetic disorders that have been identified. Some of the more common ones include: * Phenylketonuria (PKU): individual cannot properly digest/break down phenylalanine (an amino acid); may result in mental retardation and hyperactivity * Sickle-cell anemia: impaired red blood cells become hooked or “sickle” shaped preventing the cells from carrying oxygen properly and dying more quickly; may resulting in anemia and early death; more often found in African Americans * Cystic fibrosis: disease of the respiratory and digestive tracts; may result in frequent lung infections * Tay-Sachs disease: neurological disorder; usually leads to death in infants, children, and adolescents *Other abnormalities include: diabetes, spina bifida, Huntington’s disease, hemophilia Chromosome Abnormalities

* Chromosome abnormalities may exist as result of:
* Alterations in chromosome number--
* Down Syndrome> Caused by presence of extra 21st chromosome; may result in round face, flattened skull, extra fold of skin over eyelids, protruding tongue, short limbs, retardation of motor and mental abilities * Klinefelter’s Syndrome> males born with XXY mutation instead of XY; may result in undeveloped testes, enlarged breasts, and other feminine characteristics * Turner’s syndrome: females born with XO rather than XX; may result in short stature, webbed neck, infertility, and/or academic difficulty in mathematics * Alterations in chromosome structure (e.g., breaks or deletions)- * Fragile X syndrome> occurs more often in males than females; X chromosome constricted and breaks off; most often results in mental deficiency (e.g., retardation, learning disability, or short attention span)...
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