Unit 3 – GENDER DEVELOPMENT

Biological influences on gender

Role of Hormones & Genes Bio-Social Approach

Evolutionary explanation

e.g. Darwin

The effect of hormones and genes on gender development (identity + behaviour)

• Herm clip- CAH clip

Biological Psychological or just for pleasure.. ??

Role of hormones and genes

Possible Questions..

• Outline the role of hormones and genes in gender development (9 marks)

Or…• Outline the role of hormones and genes in

intersex conditions of gender development (9 marks)

Biology! •The specification requires you to know about the role of genes and hormones and sometimes •You could be asked an exam question on biological influences

sex gender Acceptable behaviour

Gender identity Gender roles

Male

XY

Male masculine male Breed-winner

manly

Female

XX

Female feminine female housewife

caring

Describing the various ways in which we distinguish between male and female:

Drawing time …

A2 Psychology Summary of role of genes / hormones in gender development

2. Pituitary gland

Testis Ovaries

Gonads

Genes instruct hormones to determine sex of individual e.g. SRY gene on the Y chromosome controls whether gonads become ovaries or testes.. By releasing testosterone/progesterone at week 8 of gestation

1. Week 8 of gestation

Testosterone - instruct gonads form Wolffian ducts - testis + penis

Progesterone – instruct gonads become Mullerian ducts – Fallopian tubes + ovaries + vagina

The roles of hormones and genes....

It is also worth noting that it is difficult to separate the role of genes from the role of hormones in trying to explain any type of behaviour.

There are 5 categories of biological sex..

1. Chromosomal sex:

• Simply put, chromosomes are the structures that hold our genes.

• Genes are the individual instructions that tell our bodies how to develop and keep our bodies running healthy.

• In every cell of our body there are 20,000 to 25,000 genes that are located on 46 chromosomes.

• These 46 chromosomes occur as 23 pairs.

• We get one of each pair from our mother in the egg, and one of each pair from our father in the sperm.

• The first 22 pairs are labelled longest to shortest. The last pair are called the sex chromosomes labelled X or Y.

• Females have two X chromosomes (XX), and males have an X and a Y chromosome (XY).

• Therefore everyone should have 46 chromosomes in every cell of their body.

• If a chromosome or piece of a chromosome is missing or duplicated, there are missing or extra genes respectively.

• When a person has missing or extra information (genes) problems can develop for that individual's health, development and gender !

These descriptions say there are 46 chromosomes and that it is a male or female.

46,XX - Normal Female Karyotype 46,XY - Normal Male Karyotype

2. Gonadal sex: males have testes and females ovaries.

• The SRY gene on the Y chromosome controls whether gonads become ovaries or testes, only if the gene is present will testes appear.

• In addition to the fact that XY chromosomes start to produce hormones from week eight of gestation and there is another surge of production after birth for the first six months.

• The testes are two egg-shaped male reproductive organs located in the scrotum. They produce sperm and the male hormone, testosterone.

• This leads to male physical characteristics and behaviour i.e. “maleness”.

NB: DHT case study below ( page 45 of your booklet).

• Females on the other hand have ovaries which lead to female characteristics and behaviour e.g. They produce oestrogen, progesterone and a small amount of testosterone.

• Many research studies have associated the role of testosterone with aggression which is why males are deemed more aggressive than females.

• This has been supported in research evidence based on rats, how well can these results be generalised? Therefore our gonads have a strong influence on our gendered behaviour.

3.Hormonal sex:Hormones are your body's chemical messengers. They travel in your bloodstream to tissues or organs. They work slowly, over time, and affect many different processes, including;

• Growth and development • Metabolism - how your body gets energy from the

foods you eat • Sexual function • Reproduction • Mood

Endocrine system

Endocrine glands, which are special groups of cells, make hormones. The major endocrine glands are the pituitary, pineal, thymus, thyroid, adrenal glands and pancreas. In addition, men produce hormones in their testes and women produce them in their ovaries.

Hormones are powerful. It takes only a tiny amount to cause big changes in cells or even your whole body. That is why too much or too little of a certain hormone can be serious. Laboratory tests can measure the hormone levels in your blood, urine or saliva.

NB: We all produce the same four main hormones males produce a lot more androgens the main one

of which is testosterone (from early gestation onwards) and females do produce a lot more oestrogen and progesterone although from birth onwards.

Men produce some amount of progesterone, but it probably has no normal function except to help produce other steroid hormones.

4. Sex of the internal reproductive structures:

• Males have Wolffian ducts which will later develop into the prostate gland, sperm ducts, seminal vesicles and testes• Females have Mullerian ducts that will later

develop into the fallopian tubes, womb and ovaries

5. Sex of the external genitals:

Males have a penis and scrotum while females have the outer lips of the vagina (labia majora).NB; the absence of testosterones in a male leads

to the development female structures.

ClipFemale reproductive system.Male reproductive system.

Describe the role of hormones and genes in gender development. (8 marks)

Plan – 1x A4 long• Use technical terms to describe role of

hormones/genes – testosterone, etc• Describe two examples of gender disorders

True False

1. Week 9 gestation is important in hormonal production

2. Testosterone triggers female sexual development

3. SRY gene makes gonads become ovaries and womb

4. The Pituitary is in the adrenal glands.5. Wolffian ducts turn into ovaries/vagina