Figures from Chapter 3

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Chapter 3Genes, Environment, and Development
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• Species Heredity
• Genetic endowment
• Common to the species
• Governs maturation and aging
• Human examples
• Two eyes, sexual maturity at 12-14 yrs.
• Natural Selection Genes allowing adaptation are
  passed on

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Evolution
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• Charles Darwin (1809-1882)
• Species characteristics
• How they change over time
• Main Arguments
• Genetic variation exists in all species
• Some genes aid in adaptation
• Kettlewells Moths Genetic variability provides
  for adaptation

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Modern Evolutionary Perspectives
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• What we do today was adaptive for ancestors
• Example mothers invest more in child rearing
• Maternity is certain paternity may not be
• Evolution gene/environment interaction
• Traits are demanded by environment
• Advantageous genes for a particular environment
  survive

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Individual Heredity - The Genetic Code
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• Zygote union of sperm and egg
• 23 pairs of chromosomes
• Each pair influences one characteristic
• Pair One from father one from mother
• Meiosis produces sperm and ova
• Mitosis cell-division process
• Creates new cells

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Genes Our Biological Blueprint

• Chromosomes
• threadlike structures made of DNA that contain
  the genes
• DNA (deoxyribonucleic acid)
• contains the genetic information that makes up
  the chromosomes
• has two strands-forming a double helix--held
  together by pairs of nucleotides

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Genes Their Location and Composition
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Karyotype
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Genes Our Biological Blueprint

• Genes
• biochemical units of heredity that make up the
  chromosomes
• a segment of DNA synthesizes a protein
• Genome
• consisting of all the genetic material in its
  chromosomes

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Genetic Uniqueness Relatedness
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• Monozygotic (MZ) twins 100 related
• 2 genetically identical individuals
• Dizygotic (DZ) twins 50 on average
• 2 ova fertilized by 2 sperm
• Siblings 50 on average
• Parent Child 50 related, shared
• Males XY Females XX

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Translation of the Genetic Code
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• Genes provide instructions for development
• Eye color and other characteristics
• Regulator genes turn on/off gene pairs
• Adolescent growth spurt
• Shut down some in adulthood

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Genotype

• A genotype refers to persons genetic heritage.

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Phenotype

• The phenotype is ones genotype expressed in
  characteristics that can be observed and
  measured.
• It includes physical traits (e.g., height,
  weight) as well as psychological characteristics
  (intelligence, personality).

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Offspring with brown eyes
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Sickle-Cell Anemia
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• Caused by hemoglobin S that reduces O2
• About 9 affected in U.S.
• Homozygous recessive (ss)
• Heterozygous (Ss) carriers
• Can transmit gene to offspring

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Sickle-Cell Anemia
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• Incomplete dominance carriers show signs of
  having recessive trait
• Will not have the disease, but sickling episodes
• Co-dominance neither gene in pair is dominant
  or recessive

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Sex-Linked Inheritance
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• Single genes located on sex chromosomes
• Actually X-linked
• Males have no counterpart on Y chromosome
• Females have counter on second X
• Requires gene on both Xs for trait
• Hemophilia, Colorblindness

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Figure 3.2
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Polygenic Inheritance and Mutations
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• Polygenic Most human characteristics influenced
  by multiple genes
• Height, weight, intelligence, temperament
• Mutations Change in structure/arrangement of
  genes
• Environmental hazards (teratogens) can cause
  mutations
• Produces new phenotype
• Sperm more likely than ova
• Harmful or beneficial (e.g., sickle-cell protects
  from malaria)

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• Errors in chromosome division Meiosis
• Too many or too few chromosomes
• Most spontaneously aborted
• Down syndrome Trisomy 21
• Physical deformities (eyelid folds, short stubby
  limbs, thick tongues)
• Mental retardation
• Related to age of mother

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Trisomy 21
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Down Syndrome (Trisomy 21)

• Physical Deformities

flattening of the back of the head slanting of
the eyelids short stubby limbs thick tongues
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• Figure 3.3

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TURNER SYNDROME (Single X chromosome - XO)

• 1/3000 females - short stature, sterile, webbed
  neck, stubby fingers, arms that turn out slightly
  at the elbow, and a low hairline in the back of
  the head

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Klinefelter syndrome1/200 malesXXY, tall,
sterile, feminine traits
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FRAGILE X SYNDROME Leg of X barely
connectedSex-linked affects mostly males

• eye vision impairments Hyper-extensible joints
  (double jointed)
• elongated face Large testicles (evident after
  puberty)
• Flat feet Low muscle tone
• High arched palate Autism and autistic-like
  behavior
• Prominent ears hand biting and hand-flapping
• Mental Retardation Hyperactivity and short
  attention span

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Genetic Diagnosis and Counseling
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• Tay-Sachs disease
• Cause recessive gene pair
• European Jews/French Canadians
• Huntingtons Disease
• Single dominant gene
• Learn about risk to unborn child
• Learn about nature, inheritance and effects of
  genetic disorders in family history

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HUNTINGTONS DISEASE
rapid, jerky involuntary movements difficulty in
speaking and swallowing cognitive decline,
depression, and occasionally delusions hallucinati
ons and obsessive compulsive disorders.
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Behavioral Genetics
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• Genetic/environment cause of trait
• Heritability estimates (genetic)
• Methods of studying
• Experimental and selective breeding attempt to
  breed particular traits into animals
• Tryons maze-bright rats indicate that activity
  level, emotion, sex drive may have strong genetic
  basis
• Twin, adoption, family studies
• Reared together or apart
• Concordance rates

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• Figure 3.4

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Estimating Influences
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• Genetic similarity
• Degree of trait similarity in family members
• Shared environmental influences
• Living in the same home
• Non-shared environmental influences
• Unique experiences (e.g., emotionality)

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Accounting for Individual Differences
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• Correlations highest in identical twins
• Genetic factors determine trait
• Correlations higher if twins reared together
• Environmental factors
• Correlations are not perfect
• Non-shared experiences
• Identical twins more alike with age

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Temperament and Personality
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• Temperament set of tendencies concerning
  emotional reactivity, activity, and sociability
  (genetic)
• Temperament correlations
• MZ twins .50 to .60
• DZ twins 0
• Personality correlations similar
• DZ shared environment unimportant
• Same home - different personalities
• Non-shared environment and genes important

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Psychological Disorders
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• Schizophrenia concordance rates
• MZ 48 DZ17
• Affected parent increases risk 13
• Inherited predisposition
• Environmental factors triggers
• Prenatal exposure to infection suspected

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Gene/Environment Correlations
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• E.g., Sociable genes
• Passive G/E correlations parents genes
  influence the environment they provide for
  children, as well as the genes the child receives
• Parents create social home
• Evocative G/E correlations childs genotype
  evokes certain reactions
• Smiley baby gets more social stimulation
• Active G/E correlations childs genotype
  influences the environment that he/she seeks
• Child seeks parties, friends, groups, etc.

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Genetic Influences on Environment
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• Finding Parents who read to their children have
  brighter children. Why?
• Environment reading to child makes them brighter
• Genetic brighter parents more informed or they
  enjoy reading themselves
• Finding Aggressive children have hostile
  parents.
• Genetic inherited behaviors
• Environment growing up with negative, hostile
  parents causes the behavior

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Controversies Surrounding Genetic Research
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• Identification of carriers of diseases and
  disorders
• Giving information which leads to abortion
• Experimenting with techniques for genetic
  alteration
• Better parenting if childs genetic
  predispositions understood