G - The role of chromosomes and hormones in sex and gender Flashcards

1
Q

Chromosomes

A

The X-shaped bodies that carry all the genetic information (DNA) for an organism.

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2
Q

Hormones

A

The body’s chemical messengers. They travel through the bloodstream, influencing many different processes, including mood, the stress response and bonding between mother and newborn baby.

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3
Q

Intersex

A

The term used to describe an individual who is neither distinctly male nor female because of a mismatch between, for example, chromosomes and genitals.

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4
Q

How many pairs of chromosomes does each body cell have?

A

23

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5
Q

What does each chromosome carry?

A

Hundreds of genes.

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6
Q

What do genes carry contain?

A

Instructions about physical and behavioural characteristics, such as eye colour and predisposition to certain mental illnesses.

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7
Q

What do sex chromosomes do?

A

Determine an individual’s sex.

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8
Q

What are the female sex chromosomes?

A

XX

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9
Q

What are the male sex chromosomes?

A

XY

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10
Q

What do Y chromosomes contain?

A

The SRY gene.

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11
Q

What does the SRY gene do?

A

Causes male physical development at the fetal stage.

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12
Q

What does SRY gene create?

A

A ‘Sex-determining Region Y protein’.

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13
Q

What is a ‘Sex-determining Region Y protein’?

A

A transcription factor that binds to DNA to control other genes (an epigenetic change).

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14
Q

What is particular about the Y chromosome?

A

It carries very little genetic material, although it does determine the sex of a child.

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15
Q

There is usually a direct link between an individual’s chromosomal sex (XX and XY) and what?

A

Their external genitalia (vagina or penis) and internal genitalia (ovaries or testes).

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16
Q

There is usually a direct link between an individual’s external genitalia (vagina or penis) and internal genitalia (ovaries or testes) and what?

A

An individual’s chromosomal sex (XX and XY).

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17
Q

What happens in sex development?

A

During prenatal development all individuals start out the same - a few weeks after conception both male and female embryos have external genitalia that look essentially feminine.

When the foetus is about three months old sex organ development is complete and lutropin is produced by the adrenal glands in both sexes.

If it is to develop as a male, the testes normally produce the male hormone testosterone which causes external male genitalia to develop. This happens because the testes contain leydig cells, which respond to lutropin by producing testosterone which drives further male development.

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18
Q

What does genetic transmission explain?

A

How individuals acquire their sex.

It may also explain some aspects of gender (a person’s sense of whether they are male or female) because of the link between genes and genitalia and hormones.

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19
Q

What are examples of well-recognised atypical sex chromosome patterns?

A

Klinefelter’s syndrome.

Turner’s syndrome.

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20
Q

How many months after conception is sex organ development complete?

A

3 months

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21
Q

What is produced by the adrenal glands 3 months after conception?

A

Lutropin.

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22
Q

In what sex is lutropin produced?

A

Both sexes.

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23
Q

What is lutropin produced by?

A

Adrenal glands.

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24
Q

How and why do the testes respond to lutropin?

A

Testes contain leydig cells which respond to lutropin by producing testosterone. This testosterone drives further male development.

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25
Q

What does lutropin cause the testes to do?

A

Testes contain leydig cells which respond to lutropin by producing testosterone. This testosterone drives further male development.

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26
Q

How many people does Klinefelter’s syndrome affect?

A

1 in 10,000 males.

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27
Q

Does Klinefelter’s syndrome affect males or females?

A

Males.

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28
Q

What is Klinefelter’s syndrome due to?

A

An XXY configuration.

29
Q

What are the chromosomes in Klinefelter’s syndrome?

A

XXY

30
Q

What is Klinefelter’s syndrome?

A

An atypical pattern of sex chromosomes - XXY.

31
Q

How are people with Klinefelter’s syndrome born and how do they develop?

A

Born with a penis and develops as a fairly normal male.

32
Q

What are the characteristics of Klinefelter’s syndrome?

A

Tend to be taller than average and may have less muscular coordination than average.

Physically they look less masculine because of reduced levels of testosterone, e.g. less facial hair, broader hips and possible breast tissue.

Such individuals are often infertile.

33
Q

What is Turner’s syndrome due to?

A

An XO configuration.

34
Q

What does it mean that in Turner’s syndrome the chromosome configuration is XO?

A

It means the second sex chromosome is partly (damaged) or completely missing.

35
Q

How many people does Turner’s syndrome affect?

A

1 in 2000 females at birth.

36
Q

Does Turner’s syndrome affect males or females?

A

Females.

37
Q

What are the chromosomes in Turner’s syndrome?

A

XO

38
Q

What is Turner’s syndrome?

A

An atypical pattern of sex chromosomes - XO.

39
Q

How are people with Turner’s syndrome born?

A

Born with a vagina and a womb.

40
Q

What are the characteristics of Turner’s syndrome?

A

Being shorter than average and having a lack of monthly periods due to underdeveloped ovaries.

There are a wide range of other symptoms such as having a small lower jaw, webbed neck, narrow hips, misshapen/irregular internal organs, nevi (chronic skin lesions) and so on - no two XO females have the same characteristics.

41
Q

What is unique about the characteristics of Turner’s syndrome?

A

No two XO females have the same characteristics.

42
Q

What is most gender development actually governed by?

A

Hormones.

43
Q

What 3 hormones are involved in gender development?

A

Testosterone, oestrogen and oxytocin.

44
Q

When is testosterone produced?

A

Prenatally (before a baby is born).

45
Q

What does testosterone affect?

A
  • The development of genitalia.

- Brain development both prenatally and later in childhood.

46
Q

How might some XY individual’s react to testosterone?

A

Some XY individuals have an insensitivity to such hormones, i.e. their bodies’ tissues do not respond to the effects of the hormone.

In extreme cases the consequence is that no external male genitalia develop.

47
Q

What can extreme cases of insensitivity to testosterone cause?

A

No external male genitalia to develop.

48
Q

Because some XY individuals have an insensitivity to testosterone, what might happen at birth and during development?

A

They are usually identified as females at birth (because no penis developed) and raised as girls, although some are identified as XY and raised as boys.

49
Q

How does testosterone affect brain development both prenatally and later in childhood?

A

For example, XX females exposed prenatally to relatively large doses of male hormones (because their pregnant mothers had been given drugs containing male hormones) later showed more tomboyish behaviour and greater interest in male-type activities (Berenbaum and Bailey, 2003).

50
Q

How can XX females be exposed to large doses of male hormones prenatally?

A

Because their pregnant mothers had been given drugs containing male hormones.

51
Q

What effect was there when XX females were exposed prenatally to relatively large doses of male hormones (because their pregnant mothers had been given drugs containing male hormones)?

A

They later showed more tomboyish behaviour and greater interest in male-type activities (Berenbaum and Bailey, 2003).

52
Q

What is the surge of testosterone during puberty responsible for?

A

Secondary sexual characteristics such as facial hair and deepening voice.

53
Q

What causes secondary sexual characteristics such as facial hair and deepening voice?

A

The surge of testosterone during puberty.

54
Q

What is the default gender?

A

Female

55
Q

Why/how is the default gender female?

A

A genetic male will develop as a female unless exposed to testosterone.

56
Q

Why don’t females need hormones to direct prenatal genital development?

A

Because a genetic male will develop as a female unless exposed to testosterone.

57
Q

Because a genetic male will develop as a female unless exposed to testosterone, what doesn’t need to direct prenatal genital development in females?

A

Females do not need hormones to direct prenatal genital development.

58
Q

What evidence is there about the prenatal affects of oestrogen?

A

For example, some recent research found that oestrogen may actually lead to smaller brain size (Shi et al. 2015).

59
Q

What major role does oestrogen play and from when?

A

From puberty onwards it promotes secondary sexual characteristics (such as breast development) and directs the menstrual cycle (increasing the blood supply to the uterus in preparation for pregnancy and maintaining it during pregnancy).

60
Q

What causes secondary sexual characteristics (such as breast development) and directing the menstrual cycle (increasing the blood supply to the uterus in preparation for pregnancy and maintaining it during pregnancy).

A

Oestrogen produced during puberty.

61
Q

What has oxytocin been called?

A

The ‘love’ hormone.

62
Q

What does oxytocin do?

A

Promotes feelings of bonding in both men and women.

Evokes feelings of contentment and calmness.

63
Q

Where is oxytocin produced?

A

In the pituitary gland.

64
Q

Why is oxytocin important in women?

A

It is important in breastfeeding because it causes milk to flow in a lactating mother.

65
Q

What is oxytocin related to in men and women?

A

Orgasm and faster wound healing.

66
Q

What does oxytocin do at times of stress?

A

Dampens the fight-or-flight response.

67
Q

What response does oxytocin trigger in females?

A

The alternative tend and befriend response (Taylor et al., 2000).

68
Q

What does the tend and befriend response in females ensure?

A

Ensures that females protect their young (tending) and form protective alliances with other women (befriending).

69
Q

Why does oxytocin trigger a response in females but not in males?

A

Because testosterone dampens the effects of oxytocin.