Psychology 220 Week 3 Notes
Psychology 220 Week 3 Notes Psych 220
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This 13 page Class Notes was uploaded by Amanda Notetaker on Sunday February 7, 2016. The Class Notes belongs to Psych 220 at University of New Mexico taught by Cheryl Bryan in Spring 2016. Since its upload, it has received 41 views. For similar materials see Developmental Psychology in Psychlogy at University of New Mexico.
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Date Created: 02/07/16
Psychology 220- Developmental Psychology Tues/Thurs 9:30-10:45am Week #3 2/2 Chapter 3: Heredity and Environment Overview: The relationship between genes and chromosomes Is twinning genetics or can a person chose to have twins How a person can have genes for something that isn’t apparent Alcoholism Down syndrome The Genetic Code A reproductive cell is called a gamete. Sperm: male reproductive cell Ovum: female reproductive cell Zygote: a single cell that every individual starts out as, formed from the union of two gametes (a sperm and ovum). **The zygote contains all of a person’s genes. Deoxyribonucleic acid (DNA): the chemical composition of the molecules that contain the genes. DNA molecules are on a chromosome. Chromosome: one of the 46 molecules of DNA (in 23 pairs) that virtually each cell of the human body contains and that, together, contain all the genes. Genes: the small section of a chromosome; the basic unit for the transmission of heredity. A gene consists of a string of chemicals that provide instructions for the cell to manufacture certain proteins. Humans have about 20,000 genes. Base pairs are the 3 billion pairs of chemicals arranged in precise order on a string of 20 amino acids. Any variation-- such as repeated pairs or missing pairs-- change the gene a tiny bit. Each variation is called an allele of the gene; these tiny variations make each person unique. Allele: a variation that makes a gene different in some way from other genes for the same characteristic. -Some genes never vary; others have several possible alleles. In a process called methylation RNA (ribonucleic acid) and additional DNA enhance, transcribe, connect, empower, silence, and alter genetic instruction. Epigenetics -The study of how environmental factors affect genes and genetic expression—enhancing, shaping, or altering the expression of genes and resulting in the phenotype that may differ markedly from the genotype. Genotype: an organism’s entire genetic inheritance; the complete set of genes in an individual. Genome: the full set of genes that are the instructions to make an individual member of a certain species. Biological Variation -There are 8 million chromosomally different ova or sperm that can be produced by a single individual. Any couple could produce 64 trillion variations of children. -Some genes are polymorphic meaning they can have two, three, or more versions. More formally called single-nucleotide polymorphisms (SNPs) Matching Genes and Chromosomes Autosomes -In 22 of the 23 pairs of chromosomes, both members of the pair are closely matched. -Those 44 chromosomes are called autosomes merding they are independent of the sex chromosomes (the 23 pair) Homozygous: referring to two genes of one pair that are exactly the same in every letter of their code. Most gene pairs are homozygous. Heterozygous: referring to two genes of one pair that differ in some way. Typically one allele has only a few base pairs that differ from the other member of the pair. Sex Chromosomes -The 23 pair of chromosomes that determine the sex of the individual. rd XY: the 23 chromosome pair that consists of an X-shaped chromosome from the mother and a Y-shaped chromosome from the father. (MALES) XX: The 23 chromosome pair that consists of an X-shaped chromosome from both the mother and father. (FEMALES) Twins Monozygotic (MZ) Twins- twins who originate from one (mono) zygote that splits apart very early in development. These are identical twins 1/3 of twin births Multiple splits constitute quadruplets or octuplets Come from same sperm and ovum all genes in common same genotype (but different phenotype) Differentiation occurs when cells begin to specialize, taking different forms at different rates Dizygotic (DZ) Twins- twins who are formed when two separate sperm fertilize two separate ova at roughly the same time. Fraternal twins 2/3 of twin births Half genes in common Assisted Reproduction Infertility- the failure to conceive a child after a year of trying Assisted Reproductive Technology (ART) is a term for techniques used to help couples conceive and sustain a pregnancy. In Vitro Fertilization (IVF)- fertilization that takes place out of a woman’s body (laboratory dish). The procedure involves mixing sperm with ova that have been surgically removed from the woman’s ovary. If a zygote is produced, it is inserted into a woman’s uterus where it may implant and develop into a baby. Intra-Cytoplasmic Sperm Injection (ICSI)- an in vitro fertilization technique in which a single sperm cell is injected directly into an ovum. From Genotype to Phenotype Genotype: all the genes of the developing person Phenotype: the observable characteristics of a person, including appearance, personality, intelligence, and all other traits Most genes are: Polygenic- a trait that is influenced by many genes Multifactorial- a trait that is influenced by many factors both genetic and environmental. o Results in a phenotype that may differ markedly from the genotype Gene-Gene Interaction -What genes do, depends on the developmental system they are in. -Genes exist in a complex network of interactions at multiple levels of organization. Human Genome Project: an international effort to map the complete human genetic code. This effort was essentially completed in 2001, though analysis is ongoing. Heritability: a statistic that indicates what percentage of the variation in a particular trait within a particular population, in a particular context and era, can be traced to genes. Additive Heredity - Some genes and alleles are additive because their effects add up to influence the phenotype. Example: height is influenced by about 180 genes, each contributing a very small amount. Dominant-Recessive Heredity -Not all genes are additive. Alleles can interact in a dominant-recessive pattern Dominant Gene: the stronger of an interacting pair More likely to be expressed Recessive Gene: the weaker of an interacting pair of genes Less likely to be expressed Every person is a carrier of recessive genes, carried on the genotype but not necessarily expressed in the phenotype. Carrier: a person whose genotype includes a gene that is not expressed in the phenotype. The carried gene occurs in half of the carrier’s gametes and thus is passed on to half of the carrier’s children. If such a gene is inherited from both parents, the characteristic appears in the phenotype. Nature vs. Nurture Nature: heredity Nurture: environment Weak Interactionist Approach: the interaction NOT as important as one component Strong Interactionist Approach: all components are equal components Studying Genetic vs. Environmental Influences Twin studies examine monozygotic vs. dizygotic twins Adoption studies examine biological vs. environmental influences Problems with twin and adoptee studies: 1. Twins (living in the same household) shared the same environment for 9 months in the womb 2. Adopted children still spent 9 months in the womb of their biological mother 3. Children in the same household have different environments 4. We still can’t tear apart nature and nurture with these studies Genotype-Phenotype Interaction Genes affect every aspect of human behavior –environment too Most environmental influences are not shared o Example: even siblings can have different environments based on the types of friends they have, the grade in school they’re in, or how they spend their free time. Genes affect traits via responses of others to genetic characteristics People choose environment that encourages genetic predispositions o We surround ourselves with people who think like us, act like us, like what we like etc. Back to the idea of carriers Organizational Hierarchy DNA in nucleus Nucleus in cytoplasm in cell Cell in tissue Tissue in organ Organ in organ system Organ system in organism Organism in socio-cultural environment Organism in physical environment Environment in ecosystem Environment in historical time... etc. Chromosomal and Genetic Problems 1. They provide insight into the complexities of nature and nurture 2. Knowing their origins helps limit their effects 3. Information combats: difference is not always deficit Down Syndrome- a condition in which a person has 47 chromosomes st instead of the usual 46, with 3 rather than 2 chromosomes at the 21 site. People with Down syndrome typically have distinctive characteristics, including unusual facial features, heart abnormalities, and language difficulties. Huntington Disease- a fatal central nervous system disorder caused by a copy number variation—more than 35 repetitions of a particular set of three base pairs. This is a dominant gene disorder. Fragile X syndrome- a genetic disorder in which part of the X chromosome seems to be attached to the rest of it by a very thin string of molecules. The cause is a single gene that has more than 200 repetitions of one triplet. This is a recessive gene disorder. Genetic Counseling -Consultation and testing by trained experts that enable individuals to learn about their genetic heritage; including harmful conditions that they might pass along to any children they conceive. 2/4 Chapter 4: Prenatal Development and Birth Overview: When do the most important parts of the fetus form? How does medical assistance affect the birth process? Substances and circumstances that harm the fetus or have no impact Development throughout pregnancy Germinal Period -First 2 weeks of prenatal development after conception -Characterized by rapid cell division and the beginning of cell differentiation Blastocyst of cells Rapid cell division and differentiation Outer cells for a shell placenta o Attach to the uterus Inner cells form a nucleus embryo Implantation: the process (about 10 days after conception) in which the developing organism burrows into the placenta that lines the uterus. Clicker Question During the germinal period what percent of all developing organism fail to grow or implant properly? A. 5% B. 20% C. 40% D. 60% Answer: D. 60% Embryonic Period rd th -3 to the 8 week -Basic forms of all body structures develop, including internal organs Embryo: mass of cells that start to form into a being Primitive streak: the thin line in the middle of the embryo Becomes neural tube central nervous system (brain and spinal column) o Develops 20-27 day after conception 4 week: head, eyes, ears, nose, and mouth Embryo is 3 millimeters long 5 week: arm and leg buds with tail (spine) 5-7th week: arms and legs appear (toes and fingers) Embryo is 2 centimeters long 8 week: basic organs and body parts (no sex organs yet) Inner cell groups separate into two layers: 1. Ectoderm- outer layer Becomes outer skin, eye lens, inner ear, nervous system 2. Endoderm- inner layer Becomes digestive system, lungs Then appears third layer: 3. Mesoderm Becomes muscles, bones, and circulatory system 2 general patterns of prenatal development: 1. Cephalocaudal- “from head to tail” a. The head develops first 2. Proximodistal- “near to far” a. The extremities form last— from the center of the body (spine) outward Clicker Question During the embryonic period what percent of all developing organisms are aborted spontaneously? A. 5% B. 20% C. 40% D. 60% E. 80% Answer: B. 20% Fetal Period -9 weeks until birth -Fetus gains about 7 pounds and organs become more mature to frdction on their own 3 month Signal for sex organs develops o Y triggers male, no Y triggers female Body parts, but organs not functioning yet 3 month old fetus on average weighs 3 ounces and is 7.5 centimeters long Middle 3 months: Cardiovascular, digestive, excretory systems Nails, teeth buds, and hair growth Increased activity in brain growth o Neurons (neurogenesis) and synapses (synaptogenesis) – organizing Age of viability: 22 weeks from conception o When the fetus could (but not certainly) survive with specialized medical care if born spontaneously Clicker Question What percent of all fetuses are aborted spontaneously before viability at 22 weeks, or are stillborn? A. 5% B. 15% C. 20% D. 40% Answer: A Final 3 Months Neurological, respiratory, and cardiovascular systems mature Lungs begin to expand and contract Valves of the heart mature Arteries and veins mature Weight gain— provides nourishment for brain Cortex forms in brain Conscious of mother’s sounds, smells, and behaviors o Fetus can hear at 28 weeks Feels mother’s movement SUMMARY OF PRENATAL DEVELOPMENT: Fetal Actions 8 weeks: generalized movements 15 weeks: fetus capable of all movements seen in newborns 6-8 months: fetal activity decreases Fetal Senses 5 months: balance, motion 5-6 months: smell and taste 6 months: respond to sound 7 months: eyes open; respond to light (causes heart rate change) Invariant Sequence: Touch is first to develop Then sense of balance Then smell and taste Then audition Then vision BIRTH: The Stages of Labor Stage 1 -Begins when uterine contractions cause cervix to dilate -Ends when cervix has opened to about 4 inches (its widest capacity) Stage 2 -Begins as soon as cervix dilation is complete -Ends with birth of baby Stage 3 -Involves expulsion of the placenta, membranes Cesarean Section (C-section): a surgical birth, in which incisions through the mother’s abdomen and uterus allow the fetus to be removed quickly, instead of being delivered through the vagina. In the United States about 34% of births are C-sections Apgar Scale -An assessment of a newborn’ health both 1 minute after birth and 5 minutes after birth -Each worth max of 2 points (0, 1, 2 scale) -Each tested 5 minutes apart Color Heartbeat Reflex Irritability Muscle Tone Respiratory Effort 7-10 GOOD Below 4 CRITICAL CARE The Brazelton Neonatal Behavioral Assessment Scale (NBAS) -A test often administered to newborns that measures responsiveness and records 46 behaviors, including 20 reflexes. Reflex: an unlearned, involuntary action or movement in response to a stimulus; occurs without conscious thought Other reflexes may be tested that are not necessary for survival but do provide an insight on the state of the brain and bodily functions. Teratogens -Agents or conditions (viruses, drugs, chemicals) that can harm prenatal development and result in defect or death. Critical period: the time of development when a particular body part of the fetus is most vulnerable The unborn child is most vulnerable during the embryonic period Behavioral teratogens: agents or conditions that can harm the brain without physical defect (hyperactive, antisocial, learning- disabled, etc.) Threshold Effect: some teratogens are relatively harmless in small doses but becoming increasingly harmful once exposure reaches a certain level— “crosses the threshold.” Types of teratogens: Caffeine: large doses associated with spontaneous abortion and low birth weight Tobacco: associated with spontaneous abortion, still births, and low birth weight Alcohol: associated with fetal alcohol syndrome (FAS) o Most at risk during first trimester o FAS: a cluster of birth defects, including abnormal facial characteristics, slow physical growth, and reduced intellectual ability, that may occur in the fetus of a pregnant woman who drinks alcohol. Pollution: higher birth defects, early post-natal death Interaction effect: the use of multiple substances can intensify each substance HIV-positive mothers can reduce risk by: o Antiretroviral drugs beginning at 14 weeks o Giving birth by cesarean section o Do NOT breastfeed Transmission > 1% False positives: the result of a laboratory test that reports something as true when it is not. Occurs with pregnancy tests and problem tests. Example: a woman is told her baby will develop Down Syndrome but when birth happens the baby shows no signs of the disease. Cerebral Palsy: a disorder that results from damage to the brain’s motor centers. People have difficulty with muscle control— impairing their speech or body movements. Anoxia: a lack of oxygen that, if prolonged, can cause brain damage or death. Can occur during birth for a second or two without causing harm to the baby. Low Birth Weight Less than 5 ½ pounds at birth LBW (2,500 grams) Very Low Birth Weight Less than 3 pounds, 5 ounces VLBW (1,500 grams) Extremely Low Birth Weight Less than 2 pounds, 3 ounces ELBW (1,000 grams) Preterm A birth that occurs 3 or more weeks before full 38 weeks (35 or less weeks after conception) Small for Gestational Age Birth weight is significantly lower SGA than expected given the time since conception. Fish controversy: US government: avoid fish to avoid ingesting certain toxic materials – birth defects British study: eat fish because it contains nutrients that benefit the fetal brain Attitudes Towards Pregnancy -Negative attitudes are associated with low birth weight and medical problems -Stress during pregnancy is associated with premature delivery and low birth weight Postpartum depression: a new mother’s feelings of inadequacy and sadness in the days/weeks after giving birth 8-15% of new mothers experience this depression Couvade: biological symptoms of pregnancy and birth experienced by fathers. Example: weight gain and indigestion during pregnancy, pain during labor. Maternal Nutrition -Pregnant women need 2,000-2,800 calorie diets -Extreme malnutrition is associated with spontaneous abortions, still births, and defects
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