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DO NOW:. Choose the part of your brain you would most hate to lose, and tell me why. Choose the part of your brain that you would like to enhance to give you a super power, and why. . Unit 3: Biological Bases of Behavior. AP Psychology Ms. Desgrosellier 10.28.2010. Neuropsychologists:.

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do now
DO NOW:
  • Choose the part of your brain you would most hate to lose, and tell me why.
  • Choose the part of your brain that you would like to enhance to give you a super power, and why.
unit 3 biological bases of behavior

Unit 3: Biological Bases of Behavior

AP Psychology Ms. Desgrosellier 10.28.2010

neuropsychologists
Neuropsychologists:
  • psychologists who explore the relationships between brain/nervous systems and behavior.
  • aka: biological psychologists, biopsychologists, behavioral geneticists, physiological psychologists, and behavioral neuroscientists.
techniques to learn about structure function
TECHNIQUES TO LEARN ABOUT STRUCTURE & FUNCTION
  • Clinical Observation (Case Study)
  • Look at injuries, diseases, etc.
techniques to learn about structure function1
TECHNIQUES TO LEARN ABOUT STRUCTURE & FUNCTION
  • Over 150 years ago people were studying patients with brain damage and linked loss of structure with loss of function.
  • Essentially losing brain tissue caused brain damage.
techniques to learn about structure function2
TECHNIQUES TO LEARN ABOUT STRUCTURE & FUNCTION
  • Phineas Gage was a level-headed, calm foreman of a railroad crew in 1848.
  • An explosion shot an iron rod through his head, severing the connections between his limbic system and his frontal cortex.
  • Gage became hostile, impulsive, and unable to control his emotions or his obscene language.
  • Autopsy revealed that the relationship between frontal lobes and control of emotional behavior.
broca s area
Broca’s area
  • Paul Broca (1861) did an autopsy on a patient named Tan, who couldn’t speak even though there was no physical damage and he could understand language.
  • Tan’s brain showed loss of tissue in part of the frontal lobe of the left central cerebral hemisphere (as did several other similar cases).
broca s area1
Broca’s area
  • It was concluded that damage to this so-called Broca’s area caused a loss of ability to speak, known as expressive aphasia.
wernicke s area
Wernicke’s area
  • Carl Wernicke found another brain area involved with understanding language in the left temporal lobe.
  • Destruction of Wernicke’s area results in loss of ability to comprehend written and spoken language, known as receptive aphasia.
do now1
DO NOW:
  • Briefly explain who Phineas Gage was and why he is important to Psychology.
lesions
Lesions
  • Precise destruction of brain tissue.
  • Enabled more systematic study of the loss of function resulting from surgical removal, cutting of neural connections, or destruction by chemical applications.
lesions1
Lesions
  • E.g. Surgery to relieve epilepsy cuts neural connections at the corpus callosum, between cerebral hemispheres.
  • Studies of patients with “split brains” have shown that the left and right hemispheres do not perform exactly the same functions.
right hemisphere
Right hemisphere:
  • nonverbal
  • spatial, musical, and holistic functions
  • identifying faces
  • recognizing emotional facial expressions
left hemisphere
Left hemisphere:
  • verbal functions
  • mathematical functions
  • analytical functions
  • language
manipulating the brain
Manipulating the brain
  • Scientists can electrically, chemically, or magnetically stimulate various parts of the brain and note effects.
  • Researchers have electrically stimulated different cortical areas of the brain during surgery.
manipulating the brain1
Manipulating the brain
  • It has enabled scientists to observe results, like:
    • the frontal cortex at particular sites caused body movement for different body parts enabling mapping of the motor cortex.
  • New research has found that you can magnetically lesion parts of the brain (temporary and so far has shown no harm)
do now2
DO NOW
  • Tell me at least three functions of the left hemisphere and three functions of the right hemisphere of the brain.
brain imaging
Brain Imaging
  • Computerized axial tomography (CAT or CT): two-dimensional x-ray slices that are passed through various angles of the brain, arranged to show the extent of a lesion.
brain imaging1
Brain Imaging
  • magnetic resonance imaging (MRI): a technique that uses magnetic fields and radio waves to produce computer-generated images that distinguish among different types of soft tissue; allows us to see structures within the brain.
brain imaging2
Brain Imaging
  • Putting one’s head into a strong magnetic field aligns the spinning atoms.
  • A pulse of a radio wave disorients the atoms briefly.
  • When the atoms return to their normal spin, they release signals that give us a detailed image of the body.
measuring brain function
Measuring brain function
  • Scientists can stick a tiny microelectrode into a single neuron to measure its activity.
measuring brain function1
Measuring brain function
  • electroencephalogram (EEG): an amplified recording of the waves of electrical activity that sweep across the brain’s surface. These waves are measured by electrodes placed on the scalp.
measuring brain function2
Measuring brain function
  • The amplified tracings are called evoked potentials when the recorded changes in voltage results from a response to a specific stimulus presented to the subject.
  • Repeated study of the read-out can help researchers filter out brain activity and find the electrical wave caused by the specific stimulus.
measuring brain function3
Measuring brain function
  • functional magnetic resonance imaging (fMRI): a technique for revealing blood flow and, therefore, brain activity by comparing successive MRI scans. MRI scans show brain anatomy; fMRI scans show brain functions.
measuring brain function4
Measuring brain function
  • Researchers compare images taken less than a second apart, they can see which parts of the brain “light up” with increased blood flow.
measuring brain function5
Measuring brain function
  • positron emission tomography (PET) scan: a visual display of brain activity that detects where a radioactive form of glucose goes while the brain performs a given task.
measuring brain function6
Measuring brain function
  • Active neurons hog the glucose (the brain’s chemical fuel), and the PET scan tracks where in the brain the radioactive glucose goes.
measuring brain function7
Measuring brain function
  • Researchers can have participants think about certain topics or do activities to see where the glucose goes (thereby showing what part of the brain is active during that activity).
organization of your nervous system
ORGANIZATION OF YOUR NERVOUS SYSTEM
  • All of the neurons in your body are organized into your nervous system.
  • The two major subdivisions are the central nervous system and the peripheral nervous system.
organization of your nervous system1
ORGANIZATION OF YOUR NERVOUS SYSTEM
  • Central Nervous System (CNS): made up of the brain and spinal cord.
  • Spinal cord: starts at the base of your back and extends upward to the base of your skull where it joins your brains.
  • Made mainly of interneuron’s and glial cells, which are all bathed by cerebrospinal fluid produced by your glial cells.
organization of your nervous system2
ORGANIZATION OF YOUR NERVOUS SYSTEM
  • Peripheral Nervous System (PNS): made up the somatic and autonomic nervous systems, and spread around your body from your spinal cord outwards.
  • Somatic Nervous System: motor neurons that stimulate skeletal (voluntary) muscle.
  • Autonomic Nervous System: motor neurons that stimulte smooth (involuntary) and heart muscle.
do now3
DO NOW
  • Describe one way of studying the brain and what it tells psychologists.
organization of your nervous system3
ORGANIZATION OF YOUR NERVOUS SYSTEM
  • The Autonomic Nervous System is divided into two parts:
  • Sympathetic Nervous System: Responses that help your body deal with stressful events, including:
  • Dilation of pupils, release of glucose from your liver, dilation of bronchi, inhibition of digestive functions, acceleration of heart rate, secretion of adrenalin from your adrenal glands, acceleration of breathing rate, and inhibition of secretion of your tear glands.
organization of your nervous system4
ORGANIZATION OF YOUR NERVOUS SYSTEM
  • The Autonomic Nervous System is divided into two parts:
  • Parasympathetic Nervous System: Calms your body following sympathetic stimulation by restoring digestive processes (salivation, peristalsis, enzyme secretion), returning pupils to normal size, stimulating tear glands, restoring normal bladder contractions, slow breathing and heart rate, etc.
organization of your nervous system5
ORGANIZATION OF YOUR NERVOUS SYSTEM
  • Turn to your neighbor and explain the two major subdivisions of the nervous system.
  • What are the 2 parts of the CNS?
  • What are the 2 parts of the PNS?
  • What are the 2 parts of the autonomic NS?
the brain
The Brain
  • Covered by protective tissue called meninges and housed in your skull.
  • The evolutionary perspective studies how the human brain has evolved. One theory breaks the brain into three sections:
  • The reptilian brain is similar to the brainstem in humans, and is responsible for maintaining homeostasis and instinctive behavior.
the brain1
The Brain
  • The old mammalian brain roughly corresponds to the limbic system that controls emotional behavior, memory, and vision.
  • The new mammalian brain or cerebral cortex, accounts for 80% of the brain’s volume and is associated with higher functions of judgment, decision-making, abstract thought, foresight, hindsight, and insight.
the brain2
The Brain
  • The surface of the cortex has peaks (gyri) and valleys (sulci), which form convolutions that increase the surface area of your cortex.
  • Deeper valleys are called fissures.
the brain3
The Brain
  • The last evolutionary development of the brain is localization of functions on different sides of your brain.
localization and lateralization of the brain s function
LOCALIZATION AND LATERALIZATION OF THE BRAIN’S FUNCTION
  • Association areas: regions of the cerebral cortex that do not have specific sensory or motor functions, but are involved in higher mental functions, such as thinking, planning, remembering, and communicating.
localization and laterlization of the brain s function
LOCALIZATION AND LATERLIZATION OF THE BRAIN’S FUNCTION
  • Contralaterality: control of one side of your body by the opposite side of your brain.
  • The left side of your brain controls the right side of your body.
  • The right side of your brain controls the left side of your body.
do now4
DO NOW
  • Draw and label the Nervous System tree (diagram that separates the parts of the nervous system)

Nervous System

slide44

Nervous System

Peripheral Nervous System

Central Nervous System

Brain

Spinal Cord

Autonomic Nervous System

Somatic Nervous System

Sympathetic Nervous System

Parasympathetic Nervous System

structure of brain brainstem
Structure of Brain: Brainstem
  • medulla: where most fibers cross above the brain stem, resulting in contralateral (opposite side) control.
  • regulates heart rate, blood flow, breathing, digestion, vomiting.
structure of brain brainstem1
Structure of Brain: Brainstem
  • pons: right above the medulla, helps coordinate movement, and is the bridge between cerebral hemispheres and both medulla and cerebellum.
structure of brain brainstem2
Structure of Brain: Brainstem
  • reticular formation: a nerve network in the brainstem (pons) that plays an important role in controlling arousal.
structure of brain
Structure of Brain
  • cerebellum: coordinates motor function integrating motion and positional information from the inner ear and muscles.
  • helps maintain balance.
structure of brain1
Structure of Brain
  • basal ganglia (basal nuclei): links the thalamus with the motor cortex and other motor areas.
  • regulates initiation of movements, balance, eye movements, and posture.
  • Involved in reward/punishment learning and focus.
  • Some nuclei (neural clusters) involved in emotion.
structure of brain2
Structure of Brain
  • thalamus: relay “station” for sensory pathways carrying visual, auditory, taste, and somatosensory information to/from appropriate areas of cerebral cortex.
  • Located at the top of the brain stem.
structure of brain3
Structure of Brain
  • hypothalamus: controls autonomic functions such as body temperature and heart rate via control of sympathetic and parasympathetic centers in the medulla.
  • Sets appetite drives (e.g. thirst, hunger, sexual desire) and behavior.
structure of brain4
Structure of Brain
  • hypothalamus:
  • Integrates with endocrine system by secretion of hormones that regulate hormones from the pituitary.
  • Helps determine biological rhythms.
structure of brain5
Structure of Brain
  • amygdala: influences aggression and fear. Coordinates fight-or-flight response.
  • important in formation of sensory memory.
structure of brain6
Structure of Brain
  • hippocampus: Enables formation of new long-term memories.
structure of brain7
Structure of Brain
  • cerebral cortex: receives and processes sensory information and directs movement.
  • Center for higher order process such as thinking, planning, judgment.
structure of brain8
Structure of Brain
  • Frontal lobe: Motor cortex strip just in front of somatosensory cortex initiates movements and integrates activities of skeletal muscles.
  • Contralateral: right/left hemisphere controls other side of body.
structure of brain9
Structure of Brain
  • Frontal lobe:
  • Includes Broca’s area: in left frontal lobe controls production of speech.
  • Interpret and control emotional behaviors, make decisions, carry out plan.
do now5
DO NOW
  • In your own words, briefly describe the following parts of the brain (including the function):
  • cerebellum medulla
  • ponsamygdala thalamus
  • hypothalamus
structure of brain10
Structure of Brain
  • Temporal lobes: center for hearing.
structure of brain11
Structure of Brain
  • Temporal Lobe:
  • Includes Wernicke’s area: in left temporal lobe, plays role in understanding language and making meaningful sentences.
structure of brain12
Structure of Brain
  • Temporal Lobe:
  • Right temporal lobe important for understanding music/tonality.
  • Sound from both ears is processed mostly contralaterally.
structure of brain13
Structure of Brain
  • Smell processed near front of temporal lobes.
structure of brain15
Structure of Brain
  • Plasticity: when one region of the brain is damaged, the brain can reorganize to take over its function.
  • e.g. phantom limb syndrome
structure and function of the neuron
STRUCTURE AND FUNCTION OF THE NEURON
  • neuron: the basic unit of structure and function of your nervous system.
  • three major functions:
    • receive information, process it, and transmit it to the rest of your body.
structure and function of the neuron1
STRUCTURE AND FUNCTION OF THE NEURON
  • glial cells: guide the growth of developing neurons, help provide nutrition for and get rid of wastes of the neuron, and form an insulating sheath around neurons that speeds conduction.
structure and function of the neuron2
STRUCTURE AND FUNCTION OF THE NEURON
  • cell body (cyton or soma): contains cytoplasm and the nucleus, which directs synthesis of neurotransmitters.
do now6
DO NOW
  • Name the four lobes of the brain and briefly describe their primary function (or an important part located there).
  • Have your notes out, including your diagram of the neuron!
structure and function of the neuron4
STRUCTURE AND FUNCTION OF THE NEURON
  • dendrites: branching tubular processes capable of receiving information.
  • axon: emerges from the cyton as a single conducting fiber (longer than a dendrite) which branches.
structure and function of the neuron6
STRUCTURE AND FUNCTION OF THE NEURON
  • terminal button (axon terminal or synaptic knob): tip of the axon.
  • myelin sheath: fatty tissue created by glial cells that insulate the axon and speeds up transmission.
structure and function of the neuron7
STRUCTURE AND FUNCTION OF THE NEURON

DENDRITES

AXON TERMINAL

CELL BODY

AXON

MYELIN SHEATH

structure and function of the neuron8
STRUCTURE AND FUNCTION OF THE NEURON
  • nucleus: holds all the genetic information of the cell.
  • node of Ranvier: gaps between the myelin sheaths.
  • Schwann’s cells: cells that create myelin.
structure and function of the neuron9
STRUCTURE AND FUNCTION OF THE NEURON

DENDRITES

AXON TERMINAL

CELL BODY

SCHWANN’S CELLS

NODE OF RANVIER

AXON

MYELIN SHEATH

NUCLEUS

structure and function of the neuron10
STRUCTURE AND FUNCTION OF THE NEURON
  • neurogenesis: growth of new neurons that takes place throughout life.
hazlo ahora
Hazloahora:
  • Think about your Unit 2 (quarterly final) exam.
  • Which section (listening, reading, writing, grammar, vocabulary, speaking) is the easiest for you? WHY?
do now7
DO NOW:
  • Which Unit (so far) has been easiest for you? Why?
structure and function of the neuron11
STRUCTURE AND FUNCTION OF THE NEURON
  • Synapse: the gap between neurons where neurotransmitters are released to attach to specific receptor sites on membranes of dendrites of your postsynaptic neurons.
  • This is called the “lock and key concept” because each neurotransmitter has a specific match on the dendrites, like a key fitting into a lock.
structure and function of the neuron13
STRUCTURE AND FUNCTION OF THE NEURON
  • neurotransmitters: chemicals stored in structures of the terminal buttons called synaptic vesicles.
  • Used by neurons to communicate with each other.
structure and function of the neuron14
STRUCTURE AND FUNCTION OF THE NEURON
  • IN YOUR NOTES, create a 4 column table to fill out (we will add rows together)
neurotransmitters
NEUROTRANSMITTERS
  • e.g. acetylcholine (ACh) causes contraction of skeletal muscles, helps regulate heart muscles, is involved in memory, and also transmits messages between the brain and spinal cord.
  • Lack of ACh is associated with Alzheimer’s disease.
neurotransmitters2
NEUROTRANSMITTERS
  • dopamine: stimulates the hypothalamus to synthesize hormones and affects alertness and movement.
  • Lack of dopamine is associated with Parkinson’s disease.
  • Too much is associated with schizophrenia.
neurotransmitters3
NEUROTRANSMITTERS
  • glutamate: excitatory neurotransmitter involved in information processing throughout the cortex and especially memory formation in the hippocampus.
  • Both schizophrenia and Alzheimer’s may involve glutamate receptors.
neurotransmitters4
NEUROTRANSMITTERS
  • Serotonin: associated with sexual activity, concentration and attention, moods, and emotions.
  • Lack of serotonin is associated with depression.
neurotransmitters5
NEUROTRANSMITTERS
  • endorphins: opioid peptide, considered the brain’s own pain killers.
neurotransmitters6
NEUROTRANSMITTERS
  • Gamma-aminobutyric acid (GABA): inhibits the firing of neurons.
  • Valium and anticonvulsant drugs increase activity of GABA.
  • Huntington’s disease is associated with insufficient GABA-producing neurons in parts of the brain involved in the coordination of movement.
  • Seizures are associated with malfunctioning GABA systems.
neurotransmitters7
NEUROTRANSMITTERS
  • Other chemicals, like drugs, can interfere with the action of neurotransmitters.
  • Agonists may mimic a neurotransmitter and bind to its receptor site to produce the effect of the neurotransmitter.
  • Antagonists: block a receptor site inhibiting the effect of the neurotransmitter or agonist.
neuron functions
Neuron Functions
  • All behavior begins with the actions of your neurons.
  • A neuron gets incoming information from its receptors spread around its dendrites.
  • The info is then sent to the cell body, where it’s combined with other incoming information.
  • Neural impulses are electrical in nature along the neuron.
do now8
DO NOW
  • Choose two neurotransmitters and describe their functions, and what happens if there is too much or too little of the neurotransmitter.
neuron functions1
Neuron Functions
  • The neuron at rest is more negative inside the cell membrane relative to outside the membrane.
  • The neuron’s resting potential results from the selective permeability of its membrane and the presence of electrically charged particles called ions near the inside and outside surfaces of the membrane in different concentrations.
neuron functions2
Neuron Functions
  • When sufficiently stimulated (to threshold), a net flow of sodium ions into the cell causes a rapid change in potential across the membrane, known as action potential.
neuron functions3
Neuron Functions
  • If your stimulation is not strong enough, your neuron does not fire.
  • The strength of the action potential is constant whenever it occurs.
  • This is called the “all-or-none principle.”
neuron functions4
Neuron Functions
  • The wave of depoloarization and repolarization is passed along the axon to the terminal buttons, which release neurotransmitters. Spaces between segments of myelin are called nodes of Ranvier.
  • Saltatory conduction: When the axon is myelinated, conduction speed is increased since depolarizations jump from node to node.
neuron functions5
Neuron Functions
  • Neurotransmitters are released into the synapse.
  • Some synapses are excitatory, meaning the neurotransmitters cause the neuron on the other side to generate an action potential (to fire).
  • Other synapses are inhibitory, reducing or preventing neural impulses.
neuron functions6
Neuron Functions
  • The sum of all excitatory and inhibitory inputs determines whether your next neuron will fire and at what rate.
  • The constant flow of neurotransmitters regulates metabolism, temperature, and respiration.
  • It also enables you to learn, remember, and decide.
neuron functions7
Neuron Functions
  • reflex: simplest form of behavior, involving impulse conduction over a few neurons.
    • The path across maybe three neurons is called a reflex arc.
  • Afferent neurons: sensory neurons that transmit impulses from your sensory receptors to the spinal cord or brain.
  • Interneurons: located entirely in your brain and spinal cord, intervene between sensory and motor neurons.
neuron functions8
Neuron Functions
  • Efferent neurons: motor neurons transmit impulses form your sensory or interneurons to muscle cells that contract or gland cells that secrete.
  • Effectors: muscle and gland cells.
neuron functions9
Neuron Functions
  • Examples of reflexes:
    • pupillary, knee jerk, sneezing, and blinking.
  • Neural impulses:

dendritesto cell bodies axons terminal buttonsneurotransmitterssynapse

  • among neurons from the receptor to the effector.
dow now
DOW NOW
  • Briefly explain how a signal travels from neuron to neuron.
  • What is the “all-or-none” principle?
the endocrine system
THE ENDOCRINE SYSTEM
  • endocrine system: consists of glands that secrete chemical messengers called hormones in your blood.
  • Hormones travel to target organs where they bind to specific receptors.
the endocrine system1
THE ENDOCRINE SYSTEM
  • Pineal gland: produces melatonin that helps regulate circadian rhythms and is associated with seasonal affective disorder.
the endocrine system2
THE ENDOCRINE SYSTEM
  • pituitary gland: Sometimes called the “master gland” because it produces stimulating hormones that promote secretion by other glands including:
  • TSH: thyroid-stimulating hormone
  • ACTH: adrenocorticotropic hormone stimulates adrenal cortex
the endocrine system3
THE ENDOCRINE SYSTEM
  • pituitary gland:
  • FSH: stimulates egg or sperm production
  • Produces ADH (antidiuretic hormone) to help retain water in your body and HGH (human growth hormone).
the endocrine system4
THE ENDOCRINE SYSTEM
  • Thyroid gland: produces thyroxine, which stimulates and maintains metabolic activities.
  • Lack of thyroxinein children can result in mental retardation.
the endocrine system5
THE ENDOCRINE SYSTEM
  • Parathyroids: Produce parathyroid hormone that helps maintain calcium ion level in blood necessary for normal functioning of neurons.
the endocrine system6
THE ENDOCRINE SYSTEM
  • adrenal glands: adrenal cortex, the outer layer, produces steroid hormones such as cortisol, which is a stress hormone.
  • Adrenal medulla, the core, secretes adrenaline (epinephrine) and noradrenaline(norepinephrine), which prepare the body for “fight or flight,” like the sympathetic nervous system.
the endocrine system8
THE ENDOCRINE SYSTEM
  • Pancreas: insulin and glucagon regulate blood sugar that fuels all behavioral processes.
  • Imbalances result in diabetes and hypoglycemia, respectively.
the endocrine system9
THE ENDOCRINE SYSTEM
  • Ovaries and testes: gonads in females and males respectively, necessary for reproduction and development of secondary sex characteristics.
do now9
DO NOW
  • Explain the four lobes of the brain.
genetics evolutionary psychology
GENETICS & EVOLUTIONARY PSYCHOLOGY
  • nature-nurture controversy: the debate about whether your behavior is determined by your heredity or history/environment.
genetics evolutionary psychology1
GENETICS & EVOLUTIONARY PSYCHOLOGY
  • Evolutionary psychologists: study how natural selection favored behaviors that contributed to survival and spread of our ancestors’ genes, and may currently contribute to our survival into the next generations.
  • They look at behaviors that are universal shared by all people.
genetics behavior
GENETICS & BEHAVIOR
  • behavioral geneticists: study the role played by our genes and our environment in mental ability, emotional stability, temperament, personality, interests, etc.
  • They look at the causes of our individual differences.
  • They believe that genes predispose our behavior.
genetics behavior1
GENETICS & BEHAVIOR
  • Twin studies are used to study the contributions of heredity and environment.
  • identical twins: two individuals who share all the same genes/heredity because they develop from the same fertilized egg or zygote.
  • a.k.a. monozygotic twins
genetics behavior2
GENETICS & BEHAVIOR
  • fraternal twins: siblins that share about half of the same genes because they develop from two different fertilized eggs or zygotes.
  • a.k.a. dizygotic twins
genetics behavior3
GENETICS & BEHAVIOR
  • Heritability: the proportion of variation among individuals in a population that is due to genetic causes.
  • Schizophrenia and general intelligence are more similar in monozygotic twins are behaviorally more similar than dizygotic twins.
genetics behavior4
GENETICS & BEHAVIOR
  • Heritability:
  • If monozygotic twins are separated at birth and raised in different environments (adoption studies), behavioral differences may reveal the contribution of environment to behavior; similarities may reveal the contribution of heredity.
genetics behavior5
GENETICS & BEHAVIOR
  • Adoption studies assess genetic influence by comparing resemblance of adopted children to both their adoptive and biological parents.
  • The children must have been adopted as infants without contact with their biological parents.
genetics behavior6
GENETICS & BEHAVIOR
  • Adoption studies
  • If the children resemble their biological parents, but not their adoptive families, with respect to a given trait, researchers infer a genetic component for that trait.
  • Alcoholism, schizophrenia, and general intelligence have shown both genetic and environmental components.
transmission of hereditary characteristics
Transmission of Hereditary Characteristics
  • Heredity characteristics are passed down by biological process.
  • Each DNA segment of a chromosome that determines that determines a trait is a gene.
  • Chromosomes carry information stored in genes to new cells during reproduction.
transmission of hereditary characteristics1
Transmission of Hereditary Characteristics
  • Normal human body cells have 46 chromosomes, except for eggs and sperms that have 23 chromosomes.
  • Males have 44 chromosomes, plus X and Y.
  • Females have 44 chromosomes, plus X and X.
transmission of hereditary characteristics2
Transmission of Hereditary Characteristics
  • At fertilization, 23 chromosomes from the sperm unite with 23 chromosomes from the egg to form a zygote with 46 chromosomes.
  • If the male contributes a Y chromosome, the baby is male.
  • Fertilization with the wrong amount of chromosomes results in an individual with chromosomal abnormalities.
transmission of hereditary characteristics3
Transmission of Hereditary Characteristics
  • Turner Syndrome: girls with only one X chromosome (XO) who are short, often sterile, and have difficulty calculating.
transmission of hereditary characteristics4
Transmission of Hereditary Characteristics
  • Klinefelter’s syndrome: males with an XXY zygote. They lack male secondary sex characteristics at puberty, develop breast tissue, and tend to be passive.
transmission of hereditary characteristics5
Transmission of Hereditary Characteristics
  • Down syndrome: individuals with three copies of chromosome-21. They are typically mentally retarded and have a round head, a flat nasal bridge, a protruding tongue, small round ears, a fold in the eyelid, and a poor muscle tone and coordination.
transmission of hereditary characteristics6
Transmission of Hereditary Characteristics
  • genotype: the genetic makeup for a trait of an individual.
  • phenotype: the expression of the genes.
transmission of hereditary characteristics7
Transmission of Hereditary Characteristics
  • homozygous gene: the condition when both genes for a trait are the same.
  • heterozygous: also called hybrid, the condition when genes for a trait are different.
  • dominant gene: the expressed heterozygous gene.
  • recessive gene: a gene that is hidden or not expressed when the genes for a trait are different.
transmission of hereditary characteristics8
Transmission of Hereditary Characteristics
  • Tay-Sachs syndrome: caused by a recessive gene and can result in progressive loss of nervous function and death in a baby.
  • Albinism: recessive trait that produces lack of pigment and involves quivering eyes and inability to perceive depth with both eyes.
transmission of hereditary characteristics9
Transmission of Hereditary Characteristics
  • Phenylketonuria (PKU): a recessive trait that results in severe, irreversible brain damage unless the baby is fed a special diet low in phenylalanine within 30 days of birth.
  • Huntington’s disease: a dominant gene defect that involves degeneration of the nervous system characterized by tremors, jerky motions, blindness, and death.
transmission of hereditary characteristics10
Transmission of Hereditary Characteristics
  • Sex-linked traits: recessive genes located on the X chromosome with no corresponding gene on the Y chromosome, which result in expression of recessive trait more frequently in males.
  • e.g. color blindness: sex-linked trait with which individual cannot see certain colors, most often red and green.