Role of chromosomes and hormones Flashcards
what are chromosomes
46 (23 pairs) biological threads (DNA) carrying the genetic information (genotypes) that code for phenotypes
which pair of chromosomes is sex based off of
23rd pair
what is the SRY gene
sex determining region of the Y gene - controls whether gonads become ovaries or testes
which chromosome determines the sex of a child
the y chromosome
when does the SRY gene affected the embryo
6 weeks into pregnancy
how does the SRY gene change the embryo
causes the gonads to develop as testes which produce the male sex hormone testosterone causing male external gentalia
what are the gonads
sex organs
what happens if the embryo has no y chromosome
no SRY gene so gonads develop as ovaries
can a woman be born with a y chromosome
yes but the SRY gene will be missing/not activate from the Y chromosome so foetus grows as a woman
what are hormones
bio-chemical messengers in the bloodstream
what is an androgen
a male sex hormone
what is the proportion of testosterone in men vs women
10 times more in men than women
what is the role of testosterone in sex
development of a male foetus in 8-24 weeks of pregnancy, secondary sexual charactertistics
when does testosterone start being produced in a foetus
8 weeks
what is the role of testosterone in gender
affects the hypothalamus, leading to masculinisation of the brain
what features are associated with the masculinisation of the brain
higher levels of aggression, competitiveness, development of areas of brain linked to spatial tasks
what difference in the hypothalamus is there between men and women
the sexual dimorphic nucleus is bigger in males
what is testosterone
steroid hormone - androgen, male sex hormone
what is the main important feature of testosterone
it begins prenatally
what is oestrogen
female sex hormone, promotes secondary sexual characteristics
what is the role of oestrogen in sex
regulation of menstrual cycle, develop secondary sexual characteristics, diminishing levels are associated with the menopause
what is the role of oestrogen in gender
PMT - premenstrual tension = feelings of emotionality, irritability, irrational
- feminisation of the brain = sensitivity, co-operation
- high level after birth = maternal caregiving
what is oxytocin
‘love hormone’ - promotes feelins of bonding in men and women
where is oxytocin produced
pituitary gland
is the affect of oxytocin greater in men or women
women
why is the affect of oxytocin greater in women
synergies with oestrogen to enhance each’s effects
what is the role of oxytocin in sex
- stimulates lactation in women
- facilitates childbirth (contractions)
- dampens fight or flight response (reducing effect of stress hormone cortisol)
what is the role of oxytocin in gender
- pair bonding behaviour for both genders
- female social behaviour in mate selection (nesting behaviour = preparation for new offspring)
what happens to oxytocin during sex
increase five-fold
- drops immediately in men after orgasm
what effect does testosterone have on oxytocin
it dampens the effect of oxytocin
what response does oxytocin trigger in women in times of stress
tend and befriend response
why did the tend and befriend response evolve in women
to protect their young and form protective alliances with other women
what are the two atypical sex chromosome patterns
- klinefelter’s syndrome
- turner’s syndrome
which gender does klinefelter’s syndrome occur in
men
which gender does turner’s syndrome occur in
women
what chromosomes does a person with klinefelter’s have
men get an extra X chromosome so the normal XY pair becomes XXY
what are the physical characteristics of klinefelter’s syndrome
- small testes
- lack facial and pubic hair
- broader hips
- infertility
- development of breast tissue
what are the psychological characteristics of klinefelter’s syndrome
- poor language and reading skills
- dyslexia
- shy
- lack of interest in sex
- handle stress badly - get emotional
what chromosomes does a person with turner’s syndrome have
women with only one complete X chromosome (second is either missing or incomplete)
what are the physical characteristics of a person with turner’s syndrome
- sterile
- no period
- webbed neck
- low set ears
- wide chest with no boobs
what are the psychological characteristics of a person with turners syndrome
- high verbal and language skills
- low visual ability
- socially immature
- bad spatial visual memory and bad maths
