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PSY 302 > Lecture 2: Heredity, Brain, Prenatal > Flashcards

Lecture 2: Heredity, Brain, Prenatal Flashcards

1
Q

What is a Genotype?

A

the genetic material an individual inherits

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2
Q

What is a Phenotype?

A

the observable expression of the genotype, including body characteristics and
behavior

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3
Q

What is Environment?

A

includes every aspect of the
individual, and his or her surroundings, other
than genes

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4
Q

What are Chromosomes?

A

structures found in the nucleus of living cells— carry genetic information

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5
Q

What is DNA?

A

Each chromosome is a single molecule of DNA (deoxyribonucleic acid),

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6
Q

What are genes?

A

– The basic units of heredity

– Each chromosome consists of thousands of genes, small segments of DNA

– Genes contain “instructions” for building specific proteins

– A gene is “expressed” if it has been turned on to make its specific protein

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7
Q

What cell did each complex human start with?

A

The ZYGOTE
– ZYGOTE = sperm (23 chromosomes) + ova (23
chromosomes)

– So each parent contributed half of your genetic
makeup

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8
Q

What are ALLELES?

A

The same gene has multiple different forms; these are called ALLELES

  • You have 2 alleles for every gene – 1 from each parent
    – HOMOZYGOUS
    – HETEROZYGOUS
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9
Q

Phenotypic plasticity?

A

The degree to which
environmental factors affect a given trait

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10
Q

Canalization?

A

Certain characteristics are restricted in their outcome, even if the environment varies widely

  • i.e., they are less susceptible to variations in the
    environment
    – Example: language
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11
Q

What is Norm of Reaction?

A

The range of possible phenotypes for a given
genotype

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12
Q

Epigenetics?

A

The complex, dynamic process
through which environments shape the expression of genes

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13
Q

Four different ways of gene-environment interacting?

A
  1. Environmental factors turn genes on/off
  2. Environmental factors alter magnitude of genetic effects on development
  3. Gene expression can affect how people respond to children – “evocative”
  4. Genotype affects the types of environments the person seeks out – “active”
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14
Q

What are neurons?

A

Neurons are communication
cells, there are approx 100 million

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15
Q

What are Synapses?

A

connective spaces
between neurons

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16
Q

What are Glia?

A

supporting cells that
produce myelin

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17
Q

What are the Stages of Brain Development?

A
  • Neurulation
    – Formation of neural tube
  • Neurogenesis
    – Birth and migration of neurons
  • Circuit formation
    – Synaptogenesis and synaptic pruning
  • Myelination
    – Formation of fatty covering on axons
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18
Q

What is Neurulation?

A

Neurulation happens 3 weeks after conception. Neural tube forms from the ectoderm, and cells inside the tube form the CNS; cells outside the tube form the PNS

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19
Q

What are the four lobes of the cerebral cortex ?

A

Frontal Lobe: Movement, attention, impulses

Partial Lobe: Touch, pain, body position

Occipital Lobe: Visual Lobe

Temporal Lobe: Smell, taste, hearing, language

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20
Q

What is Neurogenesis?

A

Proliferation of neurons through cell division and Neuron migration where they move to appropriate place in the brain

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21
Q

What is Circuit formation?

A

Most rapid during pre and postnatal periods, Overproduction: many more synapses are produced than will actually be used

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22
Q

What is Synapse pruning?

A

Experience determines which synapses will live or
die – the “USE IT or LOSE IT” phenomenon. Timing of pruning also varies across brain regions

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23
Q

What is Myelination?

A

Glia produce myelin: a lipid/protein substance and then Myelin insulates axons so that signals can travel
faster

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24
Q

Developmental Plasticity

A

The degree to which, and the conditions under which, brain development is open to
modification by the environment

  • The effect of an experience on the brain
    depends on:
    – TIMING
    – DOSE
    – DURATION
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25
Q

HOW does experience influence the developing brain?

A

There’s two different experiences
1. Experience-expectant plasticity
2. Experience-dependent plasticity

26
Q

What is experience-expectant plasticity?

A

The ability of the brain to adapt in response to sensory information is referred to as experience-expectant plasticity

– Due to pruning of synapses that were overproduced
– Sensitive periods

27
Q

Examples of experience-expectant plasticity?

A

– Vision
– babies born with cataracts

– Language
– Genie

28
Q

Critical period?

A

A very narrow period during which a particular experience must occur for development to proceed normally

  • Example: Imprinting in chicks
29
Q

Sensitive period?

A

A developmental stage during which the brain is most
susceptible to experiences, but changes are still possible
outside of this window

30
Q

Experience-dependent plasticity?

A

Changes in the brain due to an individual’s unique
personal experiences

– Due to formation of new synapses throughout the
lifespan

31
Q

Experience-dependent plasticity examples

A

– Adult violin players
– London cab drivers

32
Q

Germinal period

A

days 0-14

From conception to implantation in uterine wall (zygote)

33
Q

Embryonic period

A

weeks 3 – 8

Formation of major organs

34
Q

Fetal period

A

week 9 – birth

– Organ systems begin to function
– Significant growth

35
Q

How long does it take the zygote to become a fetus ?

A

Zygote has full complement of genetic material, half from each parent Takes about 266 days for the one-celled zygote to become a fetus of 200 billion cells

36
Q

Discuss The Germinal Period: (2 weeks)

A

Zygote travels towards
uterus

**By the 4th day after conception, the
zygote arranges itself into a hollow sphere of cells (the blastocyst) with a bulge of cells, the inner cell mass, on
one side.

**Blastocyst implants in uterine wall:
–Inner layer (embryonic disc) becomes embryo

–Outer layer (trophoblast) becomes:
*Amniotic sac
*Placenta
*Umbilical cord

37
Q

What is Cleavage?

A

The division of the zygote
into many cells. It Occurs while the zygote travels down the fallopian tube towards uterus

38
Q

Discuss The Embryonic Period (3-8 weeks)

A

The embryonic period spans the time of implantation to about the eighth week of pregnancy. During the embryonic period, cells of the embryo (the inner cell mass called the embryonic disk) begin to differentiate into specialized cells and brain regions that take on different forms and serve unique functions.

39
Q

During the embryonic period, what three layers do the cells fold to?

A
  1. Ectoderm
  2. Mesoderm
    3.Endoderm
40
Q

What is Ectoderm?

A

The outer layer or ectoderm develops into the nervous system, sensory organs, the nails, teeth, and the outer surface of the skin.

41
Q

What is Mesoderm?

A

The middle layer or mesoderm develops into muscles, bones, the circulatory system, inner layers of the skin, and other internal organs.

42
Q

What is Endoderm?

A

The inner layer or endoderm develops into the digestive and respiratory systems.

43
Q

What is cephalocaudal development?

A

Areas near the head develop earlier than those farther down, in a pattern referred to as cephalocaudal development—head before body; arms before legs.

44
Q

What is proximodistal development?

A

Embryonic growth also is characterized by proximodistal development, with areas near the center of the body developing before areas toward the periphery

45
Q

What is the important milestone during week 3 of embryonic period?

A

– 3rd week
* Neural tube (from ectoderm) becomes the brain and
spinal cord; major areas of the brain begin to divide

46
Q

What is the important milestone during week 4 of embryonic period?

A

– 4th week
* Heart begins beating; limbs, eyes, ears, and digestive
system begin to form

47
Q

What is the important milestone during week 5 of embryonic period?

A

– 5th week
* Lungs begin to form

48
Q

What is the important milestone during week 6 of embryonic period?

A

– 6th week
* Head becomes dominant; brain is differentiated

49
Q

What is the important milestone during week 7 of embryonic period?

A

– 7th week
* Nerve cells form in the brain; muscles differentiate;
sexual differentiation

50
Q

What is the important milestone during week 8 of embryonic period?

A

– 8th week
* Ears are fully formed; fetus is capable of moving

51
Q

What is the fetal period?

A

The fetal period lasts from about the ninth week of pregnancy to birth, and involves impressive changes in fetus size, brain development, sensory capacities, and learning

52
Q

How does fetal period affect growth and organ systems?

A

A period of rapid growth and refinement of organ systems
– From 1½ to 20 inches
– From 0.02 to 7.1 pounds
- Fetus becomes more responsive

53
Q

What is Habituation?

A

the fetus decreases responses to repeated or continued
stimulation, then increases
response to new sound

54
Q

Do newborn infants recognize
rhymes and stories presented before birth?

A

YES. example - cat in the hat, or native language

55
Q

Do newborn infants recognize smell and taste?

A

YES newborns also prefer
smells and tastes that are
familiar because of
prenatal exposure

56
Q

What are Teratogens?

A

Any disease, drug, or other environmental agent that can harm a developing embryo or fetus

57
Q

What are some possible teratogens?

A

– Maternal diseases
– Drugs
– Environmental hazards

58
Q

What are the three key factors determine the magnitude of a teratogen’s effects?

A
  1. Timing of exposure
  2. Amount and length of exposure (dose-response
    relation)
  3. Genetic susceptibility of the fetus
59
Q

What Is timing of exposure?

A

Teratogens affect the organs that are developing at the time of exposure, and may have no effects at all during certain prenatal periods.

60
Q

What is Amount and length of exposure (dose-response
relation)?

A

The amount of the harmful substance that reaches the fetus will determine the extent of abnormal development, which can range from no effect at all to fetal death.

61
Q

What is the Genetic susceptibility of the fetus?

A

For example, although thalidomide was tested on animals and found to be safe, the unique genetics of humans made fetuses susceptible to its negative effects.

62
Q

What other hazards are there for the fetus?

A
  • Nutrition
    – Severe malnutrition in the mother - babies born low
    birthweight, later cognitive deficits
  • Stress
    – Prolonged and severe emotional stress is associated with stunted growth, prematurity, low birthweight, and irritable infants
  • Age
    – Prime time for childbearing: 16-35 years

PSY 302 (8 decks)

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