6/4: Lecture Slides 3 + 4 + 5 Notes | Knowt (2024)

Lecture Slides 3 - The New Genetics

• The New Genetics

  • Lesson from Genetics

    • Genes affect everything

    • Nurture always matters

    • Gene expression depends partly on the social context as a person develops

    • Genome provides gene instructions that create individual, species-specific membership

  • A Quick Review

    • All living things are composed of cells

    • Each cell manufactures certain proteins according to a code of instructions stored by molecules of DNA

    • Coding DNA molecules are on a chromosome

• The Genetic Code

  • All living things are composed of cells that promote growth and sustain life according to instructions in their molecules of DNA

    • DNA (deoxyribonucleic acid)

      • Molecule that contains the chemical instructions for cells to manufacture various proteins

      • Promotes growth and sustains life

  • Chromosomes

    • Molecules of DNA

    • Consists of 46 chromosomes arranged in 23 pairs

  • 46 to 21,000 to 3 billion

    • 23 chromosome pairs (46) organized into genes

    • 21,000 genes direct specific protein formation from 20 amino acids

    • 3 billion base pairs of four chemicals

• How Proteins Are Made

  • 

• The Genetic Code

  • Difference begin with genes

    • Single nucleotide polymorphism (SNP) gene

      • 2, 3, or more versions

      • May be inconsequential or destructive

  • Same and Different Allele

    • Variation that makes a gene different in some way from other genes for the same characteristic

    • Many genes never vary; others have several possible alleles

  • Genome

    • Involves the full set of genes that are the instructions to make an individual member of a certain species

• Beyond the Genes

  • Methylation

    • RNA and DNA alter genetic instructions in a variety of ways

    • RNA regulates and transcribes genetic instructions, turning some genes and alleles on or off

  • Epigenetics

    • Study of how environmental factors affect genes and genetic expression

• The Genetic Code

  • Genetic Diversity

    • Distinguishes each person

    • Allows the human species to adapt to the pressures of the environment

• Beyond the Genes

  • Microbiome

    • All of the microbes (bacteria, viruses, fungi, archaea, yeasts) living within every part of the body (“germs”)

• Sibling Differences

  • Gametes: reproductive cells consisting of 23 chromosomes

  • Zygote: two gametes combine and produce a new individual with 23 chromosomes from each parent

  • Copy Number Variations

    • Genes with various repeats or detections of base pairs

    • May be inconsequential, lethal, or something in between

• Matching Genes and Chromosomes

  • Humans usually possess 46 chromosomes

    • 44 autosomes and 2 sex chromosomes

      • hom*ozygous, Heterozygous

    • Sex Chromosomes

      • Female: XX

      • Males: XY

  • Sex of offspring depends on whether the father’s Y sperm or X sperm fertilizes the ovum

• Determining a Zygote’s Sex

  • 

• Male-Female Variations

  • Partial gene deactivation

    • Happens when ½ of a gene pair switches off completely, possibly causing a problem if the remaining gene is destructive

    • Parental imprinting

• Uncertain Sex

  • Ambiguous Genitals: child’s sex is not abundantly clear

• Opposing Perspective: TOO MANY BOYS?

  • Preference for boys in many areas of the world

  • Ways to prevent female birth

    • Inactivating X sperm before conception

    • In vitro fertilization (IVF)

    • Aborting XX or XY fetuses

• New Cells, New People

  • Duplication and division begins within hours after conception

  • 23 pairs of chromosomes carrying all the genes duplicate, forming 2 complete sets of the genome

  • 2 sets move toward opposite sides of the zygote, and the single cell splits neatly down the middle into 2 cells, each containing the original genetic code

  • 2 cells duplicate and divide, becoming 4, which then duplicate and divide, becoming 8, and so on

• First Stages of the Germinal Period

  • Original Zygote divides into two cells, four cells, and eight cells

  • Occasionally, the cells separate completely forming the beginning of monozygotic twins, quadruplets, or octuplets

• New Cells, New People

  • At Birth

    • Zygote becomes 10 trillion cells with each carrying a complete copy of genetic instructions

• Stem Cells

  • Result from early duplication and division

  • Able to produce any other cell

• Placenta

  • Allows early genetic testing

• CRISPR

  • Developed to edit genes; forbidden for humans

• Assisted Reproduction

  • In Vitro Fertilization (IVF)

    • Sperm mixed with surgically removed ova and implanted (zygote) into woman’s uterus

    • Legal restrictions exist in some countries

• Twins and More

• From Genotype to Phenotype

  • Phenotype: observable characteristics of an organism, including appearance, personality, intelligence, and all other traits

  • Polygenic: trait influenced by many genes

  • Multifactorial: trait affected by many factors, genetic and environmental, that enhance, halt, shape, or alter the expression of genes, resulting in a phenotype that may differ markedly from the genotype

• Gene - Gene Interactions

  • Heredity (Additive, Dominant-Recessive)

  • Mother to Son (X-Linked)

• Nature and Nurture

  • Alcohol Use Disorder

    • Genes create addictive pull

    • Alcoholism is polygenic, and culture is pivotal

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  • Nearsightedness

    • Age, genes, and culture affect vision; 75% heritability

• Chromosomal and Genetic Problems

  • Why study conditions caused by extra chromosomes or single destructive genes?

    • Provide insight into the complexities of nature and nurture

    • Knowing their origins helps limit their effects

    • Information combats prejudice: difference is not always deficit

  • Spontaneous Mutations

    • Involved in many genetic and chromosomal problems, cannot be predicted in advance, and are not likely to reappear in future embryos

    • Influenced by age of mother (over 35) and father (over 40)

    • May be helpful, harmful, or harmless

  • Not exactly 46: Survival

    • 99% of surviving fetuses have 46 chromosomes

    • For remaining 1%, only 1 newborn in 166 births survives with 45, 47, or rarely, 48 or 49 chromosomes

    • Survival is more common if only some cells have 47 chromosomes and other have 46 (mosaicism)

  • Down Syndrome

    • Called trisomy-21 because the person has 3 copies of chromosome 21

    • Involves around 300 distinct characteristics from 3rd chromosome; unique individuals

  • Dominant Disorders

    • 7,000 known single-gene disorders are dominant

    • Evident to phenotype

    • Rare because people rarely live long enough to reproduce

  • Exceptions

    • Huntington Disease: Fatal CNS disorder caused by genetic miscode of more than 35 repetitions of particular triplet

    • Rare type of early-onset (before 60) Alzheimer disease

  • Recessive Disorders

    • Millions of different types, lethal conditions are rare

    • Several types are sexlinked

  • Sickle-cell Trait

    • Offers some protection against malaria

    • African carriers are more likely than noncarriers to survive

  • Fragile X Syndrome

    • Caused by more than 200 repetitions of one triplet on one gene

    • Most common form of inherited mental retardation

  • Cystic Fibrosis

    • More common among people with northern European ancestors

    • Carriers may have been protected against cholera

• Genetic Counseling and Testing

  • Genetic Testing: creates cha;;enges and opportunities

    • Misinformation is especially destructive with psychological disorders

    • Prenatal genetic testing isn’t advocated by many scientists

  • Genetic Counseling: help parents understand genetic risks

Lecture Slides 4 - Prenatal Development and Birth

• Prenatal Growth

  • 3 Main Periods: Germinal, Embryonic, Fetal

  • Can you define these terms related to timing and technology?

    • Beginning of pregnancy

    • Length of pregnancy

    • Trimesters

    • Due Date

• Vulnerability During Prenatal Development

• Germinal Period: First 14 Days

  • Zygote begins duplication and division within hours of conception

    • Development of the placenta

    • Implantation (about 10 days after conception)

    • Organism grows rapidly

• Embryonic Period: Third through Eighth Week

  • Embryo

    • Primitive streak becomes the neural tube and later forms the brain and spine of the CNS

    • Head takes shape

    • Eyes, ears, nose, and mouth form

    • Heart begins to pulsate

    • Extremities develop and webbed fingers and toes separate

• Fetus: Ninth Week Until Birth

  • Third Month

    • Rapid Growth with considerable variation

    • Average: 3 months; 3 ounces; 3 inches

    • 9th Week: SRY gene triggers development of sex organs

    • 3rd Month: Neurological sex differences begin

• Fetus: The Middle 3 Months

  • Middle 3 Months

    • Digestive and excretory system develop

    • Fingernails, toenails, and buds for teeth form, and hair + eyelashes grows

  • Age of Viability

    • Age at which a preterm newborn may survive outside the mother’s uterus if medical care is available

    • About 22 weeks after conception

    • Brian is able to regulate basic body functions

  • Brain

    • Experiences rapid growth

    • Follows proximodistal sequence from brainstem to midbrain, to cortex

    • Develops many new neurons (neurogenesis) and synapses (synaptogenesis)

    • Begins to regulate basic bodily functions as entire CNS becomes responsive

• Fetus: The FInal Three Months

  • Last Three Months

    • Involves expansion and contraction of lungs

    • Includes final maturation of heart valves, arteries, and veins

    • Provides time for extensive growth and folding in cortex

• Birth

  • Fetal Brain signals the release of hormones to trigger the female’s uterine muscles

    • Labor Begins

      • Average duration for firstborn babies: 12 hours

      • Quicker labor for later-born babies

    • Birthing Positions Vary

      • Sitting, squatting, lying down, water births

      • Cultural and personal preference

  • Most births occur in hospitals

• Newborn’s first Minutes

• Criteria and Scoring of the Apgar Scale

• Medical Assistance

  • Characteristics of childbirth depend on several variables, inluding support and encouragement during labor

    • Fathor or other relatives

    • Doula

    • Midwife

    • Medical Professional

  • Surgery

    • Cesareans (c-section):

      • Controversial and involve surgical birth

      • Vary by rates and reasons for use

      • Presnrt advantages for hospitals; more complications after birth; less beneficial bacteria in microbiome

    • C-section Rate:

      • Medically indicated about 15% worldwide (WHO)

      • Rates vary: China/50%; US/34%

  • Drugs are usually part of a US birth process:

    • Epidural

    • Induced labor (pitocin)

  • Newborn Survival:

    • 1 in 70 die worldwide; higher in poor nations

    • 1 in 250 die in US, 40 nations have better rate!

• Alternatives to Hospital Tech

  • Place of Birth

    • Hospital labor room

    • Birthing Centers

    • Home

  • Home Births

    • Planned home births are more common in many developed countries

    • Almost all babies are born at home in poorer nations

    • Some research indicates home births entail risks for the baby; every study finds benefits for the mother

• Problems and Solutions

  • Harmful Substances

    • Teratogen

    • Behavioral Teratogens

    • Prenatal Teratogens

• Risk Analysis Factors

  • Risks analysis discerns which chances are worth taking and how risks are minimized

    • Critical Time

    • Does and/or frequency of exposure (threshold effect)

    • Innate Vulnerability

    • Teratology

• Risk Analysis: The Critical Time

  • Threshold Effect

    • Certain teratogens are relatively harmless until xposure reaches a certain level

    • Thresholds are controversial

  • Example: Alcohol Consumption

    • Embryo exposed to heavy drinking can develop fetal alcohol syndrome (FAS)

      • FAS: more apparent when women are poorly nourished and cigarette smokers

• Risk Analysis: Innate Vulnerability

  • Innate Vulnerability

    • Some zygotes carry genes that make then vulnerable

    • Male fetuses are more vulnerable to teratogens than female fetuses

    • Mother’s genes affect the prenatal environment she provides

    • Neural-tube defects are more common in certain ethnic groups

• Conflicting Advice

• What do we know?

  • Prenatal teratogens can cause:

    • Structural problems during embryonic period and several diseases throughout pregnancy

    • Behavioral problems and reproductive impairment later in life

  • Social Response to Evidence is Controversial

• Prenatal Diagnosis

  • Early prenatal care

    • Protect fetal growth

    • Make birth easier

    • Render parents better able to cope

  • Early pregnancy detection

    • Provides early recognition of potential problems

    • Raises anxiety

    • Presents false positives

• Low Birthweight

  • Low birth weight (LBW)

    • Less than 2,500 grams at birth

  • Very low birthweight (VLBW)

    • Under 1,500 grams at birth

  • Extremely low birthweight (ELBW)

    • Under 1,000 grams at birth

  • Preterm

    • Birth that occurs at 35 or fewer weeks after conception

    • Usually associated with low birthweight

  • Small gestational Age (SGA)

    • Birthweight is significantly lower than expected, given the time since conception

• Low Birthweight and the Mother

• Consequences of Low Birthweight

  • High risk infacts and children

    • Later to smile, to hold a bottle, to walk, and to communicate

  • Middle childhood, formerly SGA children

    • Have smaller brain volume

• Comparing Nations

  • Fewer low-birthweight babies than two decades ago (less malnutrition); better mortality statustics

  • Rising LBW in sub-Saharan Africa due to global warming, HIV, food shortages, wars, and other problems

  • Overall lower, but differential LBW in US

• Complications During Birth

  • Rarely have single cause

  • Cerebral palsy

    • Genetic sensitivity, teratogens, maternal infection, birth complications

  • Anoxia

• The New Family: The Newborn

  • Brazelton Neonatal Behavioral Assessment Scale (NBAS)

    • Test is often administered to newborns

    • Measures responsiveness and records 46 behaviors, including 20 reflexes

    • Parents who watch their infant perform on the NBAS are amazed at the newborn’s responses

  • Newborns seek to protect themselves with three sets of reflexes

    • Maintaining Oxygen: Breathing, Hiccuping, Sneezing

    • Maintaining Constant Body Temperature: Crying, Shivering, Tucking legs to body, Pushing

    • Managing Feeding: Sucking, Rooting, Swallowing

  • Other reflexes are not necessary for survival but signify the state of brain and body functions

    • Babinski Reflex

    • Stepping Reflex

    • Palmar Grasping Reflex

    • Moro Reflex

• New Mothers

  • About half of all women experience physical problems after birth

  • Between 8% and 15% of women experience postpartum depression

    • Feelings of sadness and inadequacy

    • Symptoms from baby blues to postpartum psychosis

    • May involve struggles with adequate baby care

    • Varied causes

• New Fathers

  • Fathers Role: Being there

    • Helping mother stay healthy

    • Helping mother manage stress

    • Providing Legal acceptance

  • Couvade

    • Symptoms of pregnancy and birth experience by fathers

    • May not allow themselves to be stressed

• Parental Alliance

  • Involves commitment by both parents to cooperate in raising the child

  • Especially beneficial when infant is physically vulnerable

• Family Bonding

  • Parent-Infant Bond

    • Bonding involves strong, loving connection that forms as parents hold, examine, and feed the newborn

    • Kangaroo Care

    • Early skin-to-skin contact isn’t essential for human bonding

Lecture Slides 5 - The first two years: Biosocial Development

• Body Changes

  • To Year 1

    • Birthweight doubles by the fourth month and triples by 1 year; there is a substantial variation

    • Typical newborn grows 10 inches by 1

    • Average at birth: weight 7 pounds; length 20 in

  • From Y! To Y2

    • Physical growth slows

    • At age 2, ½ adult height; ⅕ adult weight

• Body Changes

  • Norms: defined standards of typical performance

    • Represent average measurements; individuals vary

  • Percentile: indicates rank compared to other similar people of the same age

    • Range from 0 - 100

• Weight by Gender

  • Boys typically weight more than girls

• Body Changes

  • Patterns of infant sleep

    • Newborns average 15-17 hours a day

    • Over the early weeks, REM sleep and traditional sleep declines rapidly

    • Slow-wave sleep increases

    • Individual differences due to maturation, genes, and environment

    • Caregiver response to infant behavior during sleep hours also impacts sleep patterns

    • Insufficient sleep may be a problem for parents and infant

• Co-Sleeping and Bed-Sharing

  • Asian, Latin American, and African mothers worry more about separation

  • European and North American mothers worry more about privacy and sex

  • Cohort Differences

    • Pros:

      • Quick Response Time

      • Related to Increased Response Attatchment

    • Cons:

      • Higher SIDS risks

      • Later sleep pattern problems

• Body Changes

  • Brain Development

    • Brain is the fastest growing organ

    • Brain growth affects later cognition

    • Head-sparing occurs when body is physically challenged

• Connections in the Brain

  • Neuron

    • One of billions of nerve cells in the central nervous system (CNS)

    • Communication within CNS begins with neurons

    • Most neurons are created before birth, at a peak production rate of 250,000 new cells per minute in mid-pregnancy

    • In infancy, human brain has billions of neurons

• Connecting

  • The color staining on this photo makes it obvious that the two cell videos of neurons (stained chartreuse) grow axons and dendrites to each other’s neurons

  • Tangle is repeated thousands of times in every human brain

  • Throughout life, those fragile dendrites will grow or disappear as the person continues thinking

• Basic Terms of Neurological Development

  • Axon: fiber that extends from a neuron and transmits electrochemical impulses from that neuron to the dendritres of other neurons

  • Dendrite: fiber that extends from a neuron and receives electrochemical impulses transmitted from other neurons via their axons

  • Synapse: intersection between the axon of one neuron and the dendrites of other neurons

  • Neurotransmitter: brain chemical that carries information from the axon of a sending neuron to the dendrites of a receiving neuron

  • Myelin: axon coating that speeds neuron transmission

  • Cortex: outer layers of the brain where most thinking, feeding, and sensing occurs

  • Prefrontal Cortex: area of the cortex at the very front of the brain that specializes in anticipation, planning, and impulse control.

  • Limbic System: brain parts that interact to produce emotions, including amygdala, hypothalamus, and hippocampus

  • Hippocampus: central processor of memory, especially memory for locations

  • Hypothalamus: responds to amygdala and hippocampus to produce hormones that activate other parts of brain and body

  • Cortisol: primary stress hormone whose fluctuations affect human emotions

  • Pituitary: responds to signal from hypothalamus by hormone production

• Brain Development

  • Exuberance and Pruning

    • Brain contains great excess of neurons at birth

    • Newborn brain has fewer dendrites, axons, and synapses and much less myelin than an adult brain

    • Great but temporary increase in the number of dendrites develop in an infant’s brain during the first two years of life )transient exuberance)

    • Unused dendrites whither postnatally to allow space between neurons in the brain, allowing more synapses and thus more complex thinking

• Experience Shapes the Brain

  • Necessary and Possible Experiences (Greenough and Colleagues)

    • Experience-expectant brain function

    • Experience-dependent brain function

• Face Recognition

  • Fusiform Face Area of Brain

    • Makes newborn infant adept at face recognition

  • Experiences

    • Refine face perception and trigger immediate recognition

  • Own-race effect

    • Apparent before first birthday and persists throughout life

• Harming the Infant Brain

  • Necessary Stimulation

    • Playing, allowing varied sensations, and encouraging movement are necessary for brain connections

  • Stress and the Brain

    • Overabundance of stress hormones damages later brain functioning

  • Severe Social Deprivation

    • Anecdotal evidence with human children and research with other mammals confirms that isolation and sensory deprivation harm the developing brain

  • Intervention

    • Shaken baby syndrome is a life-threatening injury that occurs when an infant is forcefully shaken back and forth

    • Motion ruptures blood vessels in the brain and breaks neural connections

• Perceiving and Moving: The Senses

  • Sensory Development

    • Typically precedes intellectual and motor development

  • Sensation

    • Response of a sensory system when it detects a stimulus

  • Perception

    • Mental processing of sensory information when the brain interprets a sensation

• From Sound to Language

  • Hearing occurs in the temporal lobe, in both hemispheres.

  • Language comprehension occurs mostly in the left hemisphere that responds to known words, and Broca’s area that produces speech.