Biological Explanation- The Role Of Chromosomes And Hormones Flashcards
What are chromosomes
Found in the nucleus of living cells which carry all the genetic information (DNA) for an organism, humans have 46 chromosomes arranged into 23 pairs in each cell- the 23rd pair determines the biological sex
What are hormones
Chemical messengers that are released into the bloodstream from glands that control and regulate the activity of certain cells and organs
What is the chromosomal structure for males and females
XX for female and XY for males
How is biological sex determined
- chromosomes (the sperm that fertilises the egg cell) determine a baby’s sex at fertilisation- all normal egg cells carry an X chromosome, and sperm carry an X or Y chromosome
- if the egg is fertilised by a Y chromosome carrying sperm, the child will be male and if the egg is fertilised by an X chromosome carrying sperm, the child will be female
What are the main hormones involved in sex and gender
oestrogen and oxytocin- female dominant
Testosterone - male dominant
What is testosterone
A male hormone produces in the testes that controls the development of male sex organs prenatally and stimulates the development of secondary sexual characteristics during puberty
What is oestrogen
A female hormone produced in the ovaries that determines sex organs prenatally and stimulates the development of secondary sexual characteristics during puberty and directs the menstrual cycle
What is oxytocin
A hormone produced in the hypothalamus which controls key aspects of the reproductive system (though testosterone inhibits its action in males) especially labour and breast-feeding in mothers, as well as nurturing/bonding behaviour in both sexes
What are the role of hormones prenatally
- once the chromosomes of the baby are determined at fertilisation, this genetic information alters the hormones released prenatally
- the hormones relegates influence which internal and external genitalia the baby will develop as individuals have gonads which are identical and have the ability to turn into either testes or ovaries
How does the role of oestrogen and testosterone determine sex
- oestrogen is produced by both XX and XY babies in the womb
- when the Y chromosome of the foetus in the womb is detected by the baby’s brain, approximately 2 months after conception, the sex-determining region on this chromosome (SRY gene) slows down the production of oestrogen, and increased testosterone production which initiates the development of male phenotypes (testes and a penis) and the characteristics of a male
- if no Y chromosome is detected, the oestrogen production continues and initiates development of female phenotypes (vagina and ovaries) and the characteristics of a female
What is a case study which supports the biological explanation for gender
- David Reiner was an identical twin born as a male but raised as a girl (Brenda) after a botched circumcision during infancy, his penis was completely removed and he underwent gender reassignment surgery
- Dr. John Money reported on the twins over the next decade claiming the reassignment surgery was successful
- David was depressed at age 13, and assumed a male gender identity (David) when he found out his true sex
- David committed suicide age 38
Why does David Reiner case study provide support for the biological explanation for gender
Suggests that nurture cannot override our nature, despite being raised as a female, David did not feel like himself- suggests his gender identity was biologically ingrained
