• Phenotypes- observable characteristics
• Genotypes- genetic information that determines our characteristics
• Chromosomes- within the nucleus of the cell are rodlike structures that store and transmit genetic information. Chromosomes come in 23 matching pairs (except sex chromosomes, which are X and Y)
• DNA- chemical substances that make up chromosomes- the double helix structure
• Genes- a segment of DNA on the chromosome. We share 98% of our DNA with chimps- so that little extra bit is responsible for our upright gait and language and cognitive abilities.
• Karyotype is a photograph of human chromosomes.
• Mitosis is the process of duplication of the normal cells, producing exact copies.

The Sex Cells

• Gametes are the sex cell, sperm and ovum. Each contains 23 chromosomes, so that when they combine to form a new person, the fertilized egg will have 23 pairs of chromosomes.
• Meiosis is the process of forming gametes with 23 chromosomes.
• Zygote is produced by sperm and ovum uniting in fertilization.
• Autosomes  are matching pairs of chromosomes- 22 pairs.
• Sex chromosomes are the 23^rd pair, either XX for a female or XY for a male.

Multiple births relates to family history of twins, older maternal age, normal build women and later births or use of fertility drugs.

• Fraternal/ dizygotic twins are most common twin, produced by fertilization of 2 ova by 2 sperm. These twins are no more alike than any siblings.
• Identical/ monozygotic twins occur when a fertilized zygote separates into 2 clusters of cells that become 2 individuals. 3/ 1,000 births.

Genetic inheritance

• Homozygous inheritance results when a pair of autosomes match, so the child reflects the similar gene characteristic.
• Heterozygous inheritance occurs when the genes for a trait are not the same- so the relationship between the 2 determines which trait will be displayed.
• Dominant-recessive inheritance determines what traits are displayed. The dominant gene will be displayed, while the recessive trait will go underground, held in the genetic matrix.
• Carriers have a recessive gene that can be passed to a child and be displayed in a later generation.
• Phenyketonuria is a defect in processing proteins and is the product of recessive genes. Because all children are tested for PKU disease and the disease can be controlled by a low protein diet, these children can escape brain damage and mental retardation.
• • Huntington disease (nervous system degeneration) is carried on a dominant gene and most diseases like that are so serious that the child doesn’t live to pass the disease on to later generations. Huntingtons, however doesn’t display until age 35+, so many people do reproduce, not knowing their genetic disorder til too late.
  • Codominance occurs when both genes influence a characteristic.
  • Sickle cell trait is present in many African Americans, but Sickle cell anemia occurs when the child inherits 2 recessive genes. Because the red blood cells are deformed, they clog the flow of blood and the sufferer has attacks of pain, swelling and tissue damage. Most die in the first 20 years.
  • Dominant and recessive characteristics: dark hair dominates blond hair; dimples dominate over no dimples, Type A blood dominates Type O blood, Rh-positive blood dominates Rh-negative blood.
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  • Dominant and recessive diseases
  • Recessive diseases
  • Cystic fibrosis
  • PKU disease
  • Sickle cell anemia
  • Tay-Sachs disease
  • Dominant diseases
  • Huntington disease
  • Marfan syndrome
  • X-linked diseases
  • Duchenne muscular dystrophy
  • Hemophilia
  • Diabetes insipidus
  • X-linked inheritance affects males more often since they don’t have a matching X chromosome to block recessive inheritance on the X chromosome. Hemophilia mostly occurs in boys. Other disabilities afflict boys more often: miscarriage, infant death, birth defects, learning disabilities, mental retardation.
  • Genetic imprinting – genes are imprinted, chemically marked so that one member of the pair is activated, regardless of its makeup. Diabetes is more often passed from the father. Asthma is more often passed from mothers. Fragile X syndrome results in moderate mental retardation, and autism yet it is expressed only when passed from the mother.
  • Mutation is a sudden, permanent change in DNA. Radiation exposure results in mutation.
  • Polygenic inheritance occurs when many genes determine the characteristic.

   

  Chromosomal Abnormalities generally occur during defects in meiosis when the sex cells are being formed. A chromosome pair won’t separate completely, etc.

  • Down syndrome is the most common chromosomal disorder, 1/ 800 births. Symptoms are mental retardation, memory, speech problems, slow motor development. There are distinct physical features in the face, often cataracts, heart and intestinal defects. With adequate stimulation and therapy, they can develop more normally. Risk increases with age of mother (1/30 at age 45)
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  • Abnormalities of the sex chromosomes- when they are severe, most pregnancies spontaneously abort in miscarriage.
  • XYY syndrome- males with specific learning disabilities.
  • XXX syndrome- girls with reading and vocabulary difficulties.
  • Klinefelter syndrome (XXY) boys with physical disabilities.
  • Turner syndrome (XO) girls who are infertile, without female organs, and disabilities in spatial relationships.

   

  Reproductive choices

  • Genetic counseling can assess a couple’s chances of producing a child with a hereditary disorder. This is essential if either person has a family history of disease or disorder. They can detect if a parent is a carrier of a disease.
  • Prenatal diagnostic methods permit detection of problems before birth, so the parents can make a decision about carrying baby to term.
  • Amniocentesis- testing a sample of fluid in the uterus to examine fetal cells for defects. 11 – 14 weeks after conception.
  • Chorionic villus sampling retrieving tissue from the membrane surrounding the fetus to examine cells. Can be done at 6 – 8 weeks. Risks of miscarriage and limb deformities.
  • Fetoscopy -  a scope with light is inserted to visually inspect the fetus for gross abnormalities. 15 – 18 weeks. Some risk of miscarriage.
  • Ultrasound-  reflection of sound waves creates a picture of fetus on a screen.
  • Maternal blood analysis can be done by 2^nd month of pregnancy, when levels of alpha-fetoprotein may indicate some problems, genetic defects.
  • Preimplantation genetic diagnosis- removing a cell or 2 from a zygote that is prepared to be implanted in the mother after in vitro fertilization.
  • Genetic engineering is developing in order to correct hereditary defects. Genes have been identified by the Human Genome Project that link to severe diseases such as cystic fibrosis, Huntington disease, Duchenne muscular dystrophy, etc. Gene therapy occurs when healthy genes are put into the defective cells to correct an abnormality.
  • Social/ moral issues of reproductive technologies
  • Donor insemination- using sperm from an anonymous donor when the husband has problems with fertility.
  • In vitro fertilization- removing the mother’s ova, fertilizing them in a dish of nutrients and implanting the zygote. Sex sorting can be done to ensure a girl or boy- particularly important if parents carry an X-linked disease.
  • Surrogate mothers are used when a woman can’t carry a pregnancy herself. The surrogate carries the implanted zygote to term and is paid a fee. Sometimes family members offer to be surrogates.
  • Cloning is only known to be successful in some animals, but there is reason to believe some scientists are working toward cloning humans- possibly to harvest parts. Very controversial.
  • Genetic testing is suggested for people holding high risks for genetic diseases. There are fears that general testing could result in discrimination against people who may have genes for cancer, heart disease, etc.
  • Adoption has become more popular as young adults begin thinking about having babies later and may have problems conceiving.  More young women are keeping their own babies, so the pool of healthy adoptees is shrinking. As a result many babies are being adopted from other countries. Adopted children do have more learning and emotional difficulties than other children, particularly if they are adopted after infancy. In general, most adoptees develop normally and are well adjusted as adults.

  Heredity and environment affect one another

  • Heritability estimates measure the extent that traits are inherited genetically.
  • Kinship studies compare characteristics of family members. Twins are compared on certain traits, parents and children, parents and adoptees.
  • Concordance rates are the percentage of instances when the 2nd twin shows a trait when it is present in one twin. Range is 0 to 100%- 100% means a trait is present 100% of the time in the 2^nd twin when found in one twin. Intelligence has .50 heritability in twins. Genetics explains half the variation in intelligence. Personality traits show less heritability than intelligence. Schizophrenia has a 50% concordance rate in identical twins, 18% for fraternal twins (still much higher than in the general population) Depression is 69% in identical twins, 25% in fraternal twins. Heritability estimates can be misapplied and used to discriminate against groups. This was the justification for the Holocaust in Germany – to rid the society of poor genetic specimens- except the groups deemed undesirable extended way beyond Jews to blacks, those with mental defects, gays, etc. The fact is that environment has a great influence on what characteristics are displayed and how disabilities are overcome.
  • Reaction range is your unique response to the environment. So your potential can be maximized or inhibited depending on stimulation in the environment.
  • Canalization is the tendency of heredity to restrict the development of a characteristic to a few outcomes. Strongly canalized behaviors are very genetically based and not subject to much environmental impact.
  • Genetic-environmental correlation – our genes influence the environments we are exposed to.
  • Passive correlation is when the child has no control over the environment. Parents construct a certain environment into which the child comes and adapts.
  • Evocative correlation is when the child evokes responses based on his/her own heredity. An active baby induces others to pay attention and respond to him. An irritable baby induces impatience in caretakers.
  • Active correlation is more common at older ages as children choose activities and friends to fit their nature.
  • Niche-picking is the active choice of environments that fit us. This may be why identical twins separated at birth, when reunited find they share many preferences.
  • Environmental influences on gene expression- the process of influence is bi-directional.
  • Epigenesis means the development resulting from ongoing bidirectional exchanges between heredity and environment. All relationships challenge us to develop out of our comfort zone. We learn who we are as we interact in the larger world.

   

• Day 1 – conception takes place.
• 7 days – tiny human implants in mother’s uterus.
• 10 days – mother’s menses stop.
• 18 days – heart begins to beat.
• 21 days – pumps own blood through separate closed circulatory system with own blood type.
• 28 days – eye, ear and respiratory system begin to form.
• 42 days – brain waves recorded, skeleton complete, reflexes present.
• 7 weeks – photo of thumb sucking.
• 8 weeks – all body systems present.
• 9 weeks – squints, swallows, moves tongue, makes fist.
• 11 weeks – spontaneous breathing movements, has fingernails, all body systems working.
• 12 weeks – weighs one ounce.
• 16 weeks – genital organs clearly differentiated, grasps with hands, swims, kicks, turns, somersaults, (still not felt by the mother.)
• 18 weeks – vocal cords work – can cry.
• 20 weeks – has hair on head, weighs one pound, 12 inches long.
• 23 weeks – 15% chance of viability outside of womb if birth premature.*
• 24 weeks – 56% of babies survive premature birth.*
• 25 weeks – 79% of babies survive premature birth.*

(*Source: M. Allen et. al., “The Limits of Viability.” New EnglandJournal
of Medicine.11/25/93: Vol. 329, No. 22, p. 1597.)

Introduction/ Summary:

The duration of pregnancy is divided into three equal segments called trimesters.  The first trimester (months 1-3) is essential to the proper development of the infant and encompasses both the ovum and embryonic period of prenatal development.  This is when all organs, nerve cells and brain cells develop.  This is when most spontaneous abortions (miscarriages) occur.  They generally are caused by abnormal development of the fetus and are nature’s way of eliminating a chromosomal abnormality.  It is vital that all necessary nutrients be available to the fetus in order to develop properly.

The second trimester (months 4-6) is often referred to as the “Golden trimester”. This is when the mother generally feels the best.  Morning sickness and nausea have generally disappeared and the mother is quite comfortable.

The third trimester comprises months 7-9.  These are important months for the baby as its organs and body systems mature and prepare to function on their own.  The fat accumulated during this time will five the baby a “head start” on life.

The prenatal development is sometimes separated into three development periods.  The first period is referred to as the period of the zygote.  This stage begins at conception and lasts until the zygote is implanted in the mother’s uterus.  It lasts for about 10-14 days.  The zygote grows to be about the size of a pinhead.  Roots grow from the zygote into the wall of the uterus where they can receive nutrients from the mother’s blood.

The period of the embryo lasts from about 2 weeks to 8 weeks after conception.  The embryo is attached to the mother by the umbilical cord (20 inches long) which reaches from the embryo’s stomach to the wall of the uterus.  The umbilical cord contains arteries which carry the embryo’s waste products away from the embryo to the mother’s blood system to be purified.  It also brings oxygenated and nutrient-rich blood back to the embryo to keep it alive.  The umbilical cord is connected to the placenta.  The placenta is an organ which serves as a medium for the exchange of nutrients and waste between the mother and the fetus.  Throughout this period, the embryo is inside the amniotic sac (a bag filled with watery substance called amniotic fluid).  The fluid will protect the developing baby against bumps, bruises and temperature changes.  During this period all of the organs that will be present at birth are formed.

The third development period is called the period of the fetus.  This period extends from the end of the second month of pregnancy until birth.  During this stage, the developing baby is referred to as a fetus.  The body parts, organs and systems which were formed during the embryo period will become much more developed and begin to function.  The fetus will begin will begin to resemble a human being and features will increase in clarity.

During the fetal period the baby may increase in length as much as twelve inches.

MONTHLY DEVELOPMENT

Month 2 – The embryo increases in length to about 1 ½ inches.  Bones and muscles begin to form.  The head grows rapidly at first, accounting for about half of the embryo’s size.  The face and neck begin to take on human form. The brain develops very rapidly.  Leg and arm buds form and grow the eyes begin converging toward the center of the face.  The mouth and nose form.  Major organs of the digestive system become differentiated.  The heart has been beating for about a month now.

Month 3 – The fetus measures about 3 inches from head to buttocks and weighs about ½ ounce.  The fetus has all of its major systems and they are functioning.  However, it is still unable to survive independently.  No new organs will need to be formed, but the ones that are present will need time to develop and mature.  The digestive system is active.  The liver and kidneys are functioning.  The fetus practices swallowing amniotic fluid, breathing amniotic fluid and its vocal chords are developing.  The roof of its mouth comes together and fuses.  Taste buds appear, sex organs continue to develop, buds for all temporary teeth are formed and bone formation begins.  During this month, arms, legs and fingers begin to make spontaneous movement. The eyelids close and are sealed shut at this time. They will reopen at about 6 months.

Month 4 – The fetus grows to almost 6 inches in length and 4 ounces in weight.  The skin is thin, loose and wrinkled and appears red because of underlying blood vessels.  The face acquires a human appearance.  The body outgrows the head at this time.  Hands and feet become well formed and finger closure is possible.  The fetal reflexes become more brisk as it begins to stir and move the arms and legs.  In males, the testes are in position for later descent into the scrotum and in females, the uterus and vagina are recognizable.

Month 5 – The fetus is now about 12 inches long and weighs about 8 ounces.  During this month the mother will probably feel the baby’s movement, called quickening.  It is suspended in a quart of amniotic fluid.  The development seems so advanced that the skin and digestive organs are not prepared to exist on their own.  Also, there is no provision for regulating body temperature.  The fetus grows a fine dark body hair called lanugo and collects vernix, which is a waxy coating to cover and protect the skin.  The nose and ears begin ossification, the skeleton hardens, and the heartbeat can now be heard.  Fingernails and toenails begin to appear and the baby will wake and sleep.  Sweat glands are formed and functioning.

Month 6 – The fetus increases in weight and is now between 1 ½ – 2 pounds.  The eyelids, which have been fused shut, are now open and completely formed.  The eyes look up, down and sideways.  Eyebrows and eyelashes are well defined and taste buds appear on the tongue and in the mouth.

Month 7 – The fetus is now about 15 inches long and weighs between 2 ½ – 3 pounds.  It can cry weakly and can suck its thumb.  The fetus can make a variety of reflex movements: startle, grasp, and swim movements.  The cerebral hemispheres cover almost the entire brain.

Month 8 – The fetus will gain 2-3 pounds during this month, which it will need to stay warm following birth.  The fingernails reach beyond the fingertips and much of the lanugo is shed.  By the end of this month, the fetus will most likely settle into the head down position.  However, the baby is capable of changing positions.

Month 9 – The fetus reaches full growth.  It measures 14-15 inches from head to buttocks and weighs 6-8 pounds.  During this last month, the baby acquires antibodies from its mother which will give it temporary immunity against some diseases.  The eyes are normally blue at birth because pigmentation is not normally formed until after a few weeks of exposure to light.  Vernix is present over the entire body.  The fetus will alternate between periods of activity and periods of quiet.  The organs increase their activity, the fetal heart rate increases to rapid rate.  Birth usually occurs approximately 280 days after the first day of the mother’s last menstrual period.

The scope of psychology includes many different fields, distinguished by interest in different psychological processes, different populations, and differeent levels of analysis. Professionals psychologists may be interested in basic research or applied techniques like therapy, or they may study humans or animals. They may focus on either internal or external processes, on changes among individuals or over time, and on the influence of either human nature or specific situations.

Because psychology is a science, all fields of psychology rely on the scientific method. The scientific methold is a way of acquiring knowledge. This particular method emphasizes the study of how real events are experienced through one’s senses, a perspective known asempiricism. Empirical research is research based on the evidence of sensory experience. A scientist conducts empirical observations, records measurements(data) of these events, and makes guesses(hypotheses) about their causes and connections. Many hypotheses about similar sets of events are summarized in theories, which are models or broad explantions of cause-and-effect connections.

In conducting scientific research on behaviour and mental processes, psychologists may study either human or nonhuman subjects. Research can be conducted in the natural settings where the events occur(referred to as the field) or in the laboratory, which is any controlled environment. In laboratory research, psychologists control who the subjects are as well as the conditions they ecounter. In all research, whether human or non human, field or laboratory, psychologists record their observations and formulate hypotherses in order to explain behaviour and mental processes. The goal of psychology is to understand, predict, and control behaviour and mental processes.

William Sheldon (1940, 1942,) classified personality according to body type. He called this a person’s somatotype.

Sheldon identified three main somatotypes.

1. Endomorph [viscerotonic]

relaxed, sociable, tolerant, comfort-loving, peaceful

plump, buxom, developed visceral structure

2. Mesomorph [somatotonic]

active, assertive, vigorous, combative

muscular

3. Ectomorph [cerebrotonic]

quiet, fragile, restrained, non-assertive, sensitive

lean, delicate, poor muscles

Ancient Greek philosophers such as Hippocrates 400 BC and Galen, 140/150 AD classified 4 types of “humors” in people.  Each type was believed to be due to an excess of one of four bodily fluids, corresponding to their character.  The personalities were termed “humors”.