The role of chromosomes: Gender Flashcards
What are chromosomes?
Chromosomes are made from DNA.
Males and females differ in a pair of chromosomes known as the sex chromosomes. Females have two X chromosomes (XX) in their cells, while males have one X and one Y chromosome (XY).
There are 46 chromosomes in the human body arranged into 23 pairs, the 23rd pair determined biological sex.
What are hormones?
Hormones are chemical messengers released from endocrine glands that influence the nervous system to regulate the physiology and behaviour of individuals.
Prenatally, hormones (in the womb) act upon brain development and cause the development of the reproductive organs.
At puberty, during adolescence, a burst of hormonal activity triggers the development of secondary sexual characteristics such as pubic hair.
What is the chromosomal structure of females?
What is the chromosomal structure of males?
XX
XY
What is intersex?
A term used to describe an individual who is neither a male nor female because of a mismatch between chromosomes and genitals.
What is the role of testosterone?
Testosterone is believed to be responsible for typically male behaviours, such as aggression, competitiveness and superior visuospatial abilities. Males also have a surge of testosterone during puberty, and this is responsible for secondary sexual characteristics such as facial hair and a deepening voice.
What is the role of oestrogen?
Oestrogen is one of the main female sex hormones. It is needed for puberty, the menstrual cycle, pregnancy, bone strength and other functions of the body. Oestrogen levels vary throughout the menstrual cycle.
What is the role of oxytocin?
Promotes feelings of bonding, contentedness and calm. It is particularly important in breastfeeding to promote lactation and is released at times of stress to reduce the fight-flight response. Females have higher levels of oxytocin than men, as oestrogen has been found to increase oxytocin secretion.
What is Klinefelter’s syndrome?
Klinefelter’s syndrome occurs due to an atypical sex chromosome pattern which affects the development of males who have an extra X chromosome (XXY). Klinefelter’s syndrome is found in around 1 in 1,000 males. The most common symptom is infertility, but males with Klinefelter’s syndrome may also have small, firm testes, a small penis, sparse pubic, armpit and facial hair, enlarged breasts (called gynecomastia), tall stature, and abnormal body proportions (long legs, short trunk).
What is Turner’s syndrome?
Turner syndrome occurs due to atypical sex chromosome patterns and affects development in females who only have one X chromosome (XO); it occurs in 1 in 2,000 females. The most common feature is short stature, which becomes evident by about age 5. An early loss of ovarian function is also very common, so many affected girls do not undergo puberty unless they receive hormone therapy, and most are unable to conceive. One-third to one-half of those with Turner syndrome are born with a heart defect. There is also a wide range of other symptoms such as a small lower jaw, webbed neck, narrow hips, and misshapen internal organs.
A03: The role of chromosomes and hormones in sex and gender
- RLA
- Nature nurture debate
- The role of culture and social influences
- Challenging biological determinism
A03: RLA
Research into patients with Klinefelter’s Syndrome and Turner’s Syndrome has seen a development of therapies to improve the quality and duration of their lives. For example, treating stunted growth often seen with Turner’s Syndrome by the application of growth hormones and the treatment of Klinefelter’s Syndrome with testosterone has seen those with the condition develop a less passive nature. This is a strength because it shows that such research into gender in the field of psychology is having a positive effect on the human experience. In addition, such research has allowed for symptoms of these disorders to be effectively treated.
A03: Support for the nature-nurture debate
The study of the influence of genes and hormones in gender development is a classic example of the Nature-Nurture debate. In this case, the evidence seems to suggest that gender is primarily determined by biology but can be modified by social-environmental factors: for example, gender is expressed by men and women in different ways in different cultures, and notions of acceptable behaviours for the genders have changed dramatically in Europe over the past century (feminist and gender equality).
A03: The role of culture and social influences
Study of the Batista family from the Dominican Republic where four children were born with external female genitalia and raised as girls. The large amounts of testosterone produced during puberty caused their male genitalia to appear externally. These children were genetically XY but the external male genitalia had not appeared because of an inherited gene that caused testosterone insensitivity. It is said that the ‘girls’ accepted their new male role without any difficulty. It is suggested that the ease of transition highlights the importance of culture. In a community prepared to accept more fluidity in gender roles, it seemed to be relatively easy to move between roles, which may be more difficult in Western culture
A03: Challenging biological determinism
John Money claimed that biological sex was not the main factor in gender development. Argued that sex of rearing was much more important and recommended intersex individuals could be successfully raised as either a boy or a girl. Further, support this as they studied 16 genetic males born with almost no penis. Two were raised as males and remained as males. The remaining 14 were raised as females, and of these, eight re-assigned themselves as males by the age of 16. Such research shows that biological factors have a key role in gender development.
