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problem 1 Flashcards

1
Q

What are the three phases of prenatal development?

A
  1. period of the zygote
  2. period of the embryo
  3. period of the foetus
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2
Q

What happens in the period of the zygote?

A
  • starts at conception and ends at implantation (10 to 14 days)
  • ovum splits into multiple cells through mitosis as it travels down the fallopian tube until you get the blastocyst
  • the inner layer of the blastocyst becomes the embryo, the outer layer becomes tissue that protect and nourish it
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3
Q

What is implantation?

A
  • implantation is when the blastocyst attaches to the uterine wall and taps into the pregnant woman’s blood supply
  • takes place 6 to 10 days after conception
  • the period of the zygote ends when this has happened
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4
Q

What support structures are developed in the period of the zygote?

A
  • blastocyst develops 4 support structures once implanted
  • Amnion: membrane around the developing organ
  • Yolk-sac: produces blood cells until the embryo is capable of producing its own, it is attached to the chorion
  • Chorion: surrounds the amnion and eventually becomes the lining of the placenta
  • Allantois: forms the embryo’s umbilical cord
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5
Q

What is the role of the placenta?

A
  • provides nourishment and respiration, while eliminating metabolic wastes
  • the umbilical cord connects the embryo to the placenta
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6
Q

What happens in the period of the embryo?

A
  • lasts from 3rd to 8th week
  • period of fastest growth
  • development of basic organs
  • high susceptibility to damage
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7
Q

Which organs develop during the period of the embryo and when?

A
  • 3rd week, embryo develops into three cell layers:
    • Ectoderm (outer layer which becomes the nervous system–from the
      neural tube, skin, and hair)
    • mesoderm (middle layer which becomes muscles, bone, and
      circulatory system)
    • endoderm (inner layer including the digestive tract, lungs, urinary
      tract, and other vital organs)
  • 4th week: heart is formed and beats
  • 7/8 weeks: sexual development begins
  • embryo’s circulatory system functions on its own now
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8
Q

What happens in the period of the foetus?

A
  • 3 to 9 months
  • growing and refining organs
  • end of the third month, it has all the body parts
  • 5 months, it has reflexes
  • covered in vernix to prevent chapping and lanugo helps vernix stick to the skin (it is body hair)
  • CNS will be well developed by the end
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9
Q

What is the difference between monozygotic and dizygotic twins?

A
  • monozygotic (identical): developed from a single zygote and have identical genes
  • dizygotic (fraternal): mother releases two ovums, each fertilised by different sperm
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10
Q

What is a regulatory gene?

A

Gene that regulates the expression of other genes

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11
Q

What is the genotype and the phenotype?

A
  • genotype: the genetic makeup of an organism
  • phenotype: the detectable expression of this genotype
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12
Q

What is mitosis and meiosis?

A

mitosis
- you start with a diploid cell (46 chromosomes). Everything in the cell is duplicated and the cell then splits in two. The two new cells have the same DNA, functions, and genetic code of the original cell
- somatic cells (any cell of a living organism other than the reproductive cells) undergo mitosis

Meiosis
- important for reproduction to produce gametes (sex cells)
- a diploid cell splits into 4 haploid (23 chromosomes) cells over two stages
- Cell duplicates (92 chromosomes), crossing over takes place, the cell
divides into two (46 each) which further divide into two (each with 23
chromosomes)
- contains only half the DNA of the original cell
- germ cells undergo meiosis

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13
Q

What are the chromosome makeup that differentiate boys from girls?

A
  • Females have XX chromosomes, males have XY chromosomes
  • egg cell always has an x cell, sperm either has x or y
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14
Q

What are autosomes?

A
  • body cells aside from sex cells, pairs of chromosomes that are the same in males and females
  • humans have 22 pairs of autosomes and one pair of sex chromosomes
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15
Q

What abnormalities can occur in autosomes?

A
  • trisomy: the presence of an extra chromosome in some or all of the body’s cells
  • example: trisomy 21 (down syndrome), caused by having three copies of chromosome 21 instead of the usual two copies
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16
Q

What are dominant and recessive genes?

A
  • Dominant: The gene that has more power, thus will be expressed
  • Recessive: The gene with less power, that will not be expressed in the presence of a dominant gene
17
Q

What is co-dominance?

A
  • the presence of two dominant genes
18
Q

What is polygenic inheritance?

A
  • A characteristic impacted by multiple genes
  • Examples: Height, hair colour, eye colour, intelligence, skin colour, personality
19
Q

What is a teratogen?

A
  • pollutant substances, medications, drugs, malnutrition, stress, radiation, diseases that the mother has (diabetes, STDs), age, blood types (late pregnancy or birth), caffeine, rubella, alcohol, anti-depressants that can cause birth defects
20
Q

What are the effects of the following teratogens (alcohol, hallucinogens, marijuana, tobacco, caffeine, nutrition and STDs)?

A
  • alcohol: foetal alcohol problem, causes physical problems and problems with behaviour and learning, alcohol has transgenerational epigenetic effects
  • hallucinogens: LSD increases the risk of limb deformities
  • marijuana: changes amygdala + behavioural abnormalities
  • tobacco: restricts foetal growth, increase risk of stillbirth (the death or loss of a baby before or during delivery)
  • caffeine: increase risk of miscarriage
  • nutrition: lack of nutrients can cause stunted child growth
  • STDs: genital herpes (infection takes place during birth, can cause blindness, brain damage, no cure for it), AIDS (spreads through the exchange of bodily fluids, causes birth defects)
21
Q

What are the effects of these female chromosomal abnormalities (turners syndrome and super-female)?

A
  • turners syndrome: lacking sexual development at puberty, female is sterile, below average spatial ability
  • super-female: caused by inheriting more then two X chromosomes, no physical differences, female is still fertile, some intellectual difiencies
22
Q

What are the effects of these male chromosomal abnormalities (klinefelters syndrome, super-male)?

A
  • klinefelters syndrome:

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