The role of chromosomes and hormones in gender and sex development

Question 1

Identify females and male chromosome structure

Answer 1

• Male: XY

- Female: XX

Question 2

Describe the process of how sex is determined

Answer 2

• An egg cell carries an X chromosome but a sperm cell can carry either a X or Y chromosome.
• If the sperm cell that fertilises the egg is carrying an X chromosome the embryo will become a female however if it is carrying a Y chromosome the embryo will become a male.
• The Y chromosome causes the embryo to develop into a male as a result of it carrying the SRY gene. The SRY gene is responsible of developing the Gonads at 8 weeks into testes which then leads to the production of androgens such as testosterone.
• Testosterone is responsible for the development of male physical characteristics, reproductive organs, masculine behaviour such as aggression and also acts on the developing areas responsible for spatial skills.

Question 3

What are gonads?

Answer 3

Gonads are reproductive organs that are identical in both XX or XY embryos until the 8th week of development.

Question 4

Identify the hormones responsible for sex and gender development.

Answer 4

• Testosterone
• Oestrogen
• Oxytocin

Question 5

Outline the role of testosterone in gender and sex development.

Answer 5

• Testosterone is responsible for the development of physical male characteristics such as increased muscle mass
• it is also responsible for behavioural characteristics such as aggression

Question 6

Outline the role of oestrogen in gender and sex development.

Answer 6

• It is a female hormone that is responsible for menstruation and the development of female physical characteristics
• It is also responsible for behaviour during menstruation such as an increase in emotionality and irritability.

Question 7

Outline the role of Oxytocin in gender and sex development.

Answer 7

• There are higher levels of Oxytocin in females than males as they give birth
• It is responsible for suppressing the stress hormone cortisol and promoting the release of bonding hormones.
• It is also responsible for uterus contractions during child birth.

Question 8

What is Congenital Adrenal Hyperplasia (CAH)?

Answer 8

• It is an inherited disorder that causes the adrenal glands to unable to produce certain steroid hormones.
• Girls with CAH will have normal internal reproductive hormones but ambiguous external genitalia

Question 9

Outline the case of David Reimer.

Answer 9

• David Reimer suffered from his penis being burned off during circumcision as an infant
• His mum decided to raise David as a female as a result of Professor John Money claiming nurtutre and the environment was the determining factor for gender development
• David underwent reconstructive surgery at 2 years old conducted by Professor John money, he was then raised as a girl in every possible way. the type clothes he was given, the types of toys he was given changed and he was also injected with oestrogen
• At 14 years old David Reimer was told he was born a male and he developed hatred towards everyone as he claimed he always felt like a boy and later on went to have reconstructive surgery to become a male again
• This case study shows us that the chromosomes and nature are the determining factor for sex and gender development as David Reimer claimed he always felt like a boy and didn’t identify with his gender identity.

Question 10

AO3 for role of chromosome and hormones in sex development

Answer 10

• Bautista family
• Hines and Kaufman (CAH research)
• Mice
• Huston(SLT)

Question 11

Outline how Koopmans research into mice supports the role of chromosomes for gender development.

Answer 11

-He implanted the SRY gene found in Y chromosomes into mice who lacked it. They turned into males.

Question 12

Outline how research into the Bautista family supports the role of chromosomes on gender development.

Answer 12

• McGinley studied the Bautista family from the Dominican Republic. Four of their ten children have changed from being born and raised as girls into muscular men.
• They were born with female genitalia and normal female body shape until the age of 12. They developed testes.
• They had a genetic variation that caused the SRY gene to not be expressed until puberty.
• This shows that chromosomes and hormones are responsible for gender rather than the environment.

Question 13

Outline Hines and Kaufman’s research into CAH

Answer 13

They found girls with CAH choose boys and girls equally as favourite playmates. Girls without CAH choose other girls 80-90% of the time as their favourite playmates. The CAH girls were also given feminising surgery and were raised as girls.

-This shows Genetics do play a role on the gender behaviours displayed by individuals.