Chromosomes and Hormones involved in Sex & Gender Flashcards

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1
Q

How are chromosomes involved in sex/gender?

A
  • Humans have 23 pairs of chromosomes
  • Females have XX and males have XY chromosomes.
  • The Y chromosome contains the SRY gene, which causes the male physical development at the fetal stage.
  • SRY gene creates (sex-determining region Y protein’ - a transcription factor that binds to DNA to control other genes.
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2
Q

How is the sex developed?

A
  • Every foetus appears the same until a few weeks after conception.
  • Sex organ development is complete at around 3 months after conception.
  • Lutropin is then produced in both sexes in the adrenal glands.
  • Testes contain Leydig cells, which respond to lutropin by producing testosterone.
  • Testosterone drives further male development.
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3
Q

What are the 2 intersex atypical sex chromosome patterns?

A
  • Klinefelter’s syndrome (1 in 10,000 males)

- Turner’s syndrome (1 in 2,000 females)

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4
Q

What is Klinefelter’s syndrome?

A
  • XXY configuration (extra X chromosome)
  • Child born with penis and develops male traits
  • Usually infertile, lack muscular definition and have feminised masculine characteristics
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5
Q

What is Turner’s syndrome?

A
  • Due to ‘X0’ configuration (one chromosome is damaged or missing)
  • Born with both vagina and womb but underdeveloped ovaries
  • No monthly period, physically short/stout build
  • Can have webbed neck, narrow hips, irregular internal organs.
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6
Q

How is testosterone involved in sex/gender?

A
  • Produced before birth
  • A foetus can be insensitive to testosterone (intersex)
    • No formation of male genitalia
    • Often born/raised as girls because no penis/testicles are visible
    • Some are identified as XY and raised as boys
  • Brain development is affected by testosterone. Studies show XX females are ‘tomboyish’ and prefer masculine activities in this case.
  • Testosterone surges in puberty drive secondary male characteristics
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7
Q

How is oestrogen involved in sex/gender?

A
  • Present in all cases for the foetus - default gender is female.
  • Oestrogen level is associated with smaller brain size.
  • Promotes secondary female sex characteristics in puberty.
  • Controls menstrual cycle through increasing blood flow to uterus.
  • Elevated during pregnancy.
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8
Q

How is oxytocin involved in sex/gender?

A
  • Produced in pituitary in response to skin-to-skin contact.
  • Promotes bonding behaviour.
  • Causes milk production.
  • Enables post-orgasm bliss.
  • Helps in wound-healing.
  • Dampens fight-or-flight response in women and is related to ‘tend and befriend’.
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9
Q

Evaluate the use of hormones/chromosomes in explaining sex and gender.

A

P - Biological determinism –> Money & Erhardt (1972) claimed only sex rearing determined gender.
E - Money advised parents to raise intersex children however they liked, regardless of genetics/hormones . ‘John/Joan’ study (David Reimer) - unsuccessful suggesting gender is biologically determined
E - Further studies support; Reiner & Gearhart (2004).
L - Therefore, gender is due to nature even though nurture may contribute.

P - Real-world applications
E - Intersex people who will develop problems, can be identified at birth and given proper treatment during puberty. This can negate the effects almost entirely.
E - Olympics ruled in 1991 that genetic sex didn’t matter for participation, after testing since 1968. Individuals who are obviously physically male are still excluded from female events.
L - This means biological research into gender development is ecologically valid.

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