G - The role of chromosomes and hormones in sex and gender Flashcards
Chromosomes
The X-shaped bodies that carry all the genetic information (DNA) for an organism.
Hormones
The body’s chemical messengers. They travel through the bloodstream, influencing many different processes, including mood, the stress response and bonding between mother and newborn baby.
Intersex
The term used to describe an individual who is neither distinctly male nor female because of a mismatch between, for example, chromosomes and genitals.
How many pairs of chromosomes does each body cell have?
23
What does each chromosome carry?
Hundreds of genes.
What do genes carry contain?
Instructions about physical and behavioural characteristics, such as eye colour and predisposition to certain mental illnesses.
What do sex chromosomes do?
Determine an individual’s sex.
What are the female sex chromosomes?
XX
What are the male sex chromosomes?
XY
What do Y chromosomes contain?
The SRY gene.
What does the SRY gene do?
Causes male physical development at the fetal stage.
What does SRY gene create?
A ‘Sex-determining Region Y protein’.
What is a ‘Sex-determining Region Y protein’?
A transcription factor that binds to DNA to control other genes (an epigenetic change).
What is particular about the Y chromosome?
It carries very little genetic material, although it does determine the sex of a child.
There is usually a direct link between an individual’s chromosomal sex (XX and XY) and what?
Their external genitalia (vagina or penis) and internal genitalia (ovaries or testes).
There is usually a direct link between an individual’s external genitalia (vagina or penis) and internal genitalia (ovaries or testes) and what?
An individual’s chromosomal sex (XX and XY).
What happens in sex development?
During prenatal development all individuals start out the same - a few weeks after conception both male and female embryos have external genitalia that look essentially feminine.
When the foetus is about three months old sex organ development is complete and lutropin is produced by the adrenal glands in both sexes.
If it is to develop as a male, the testes normally produce the male hormone testosterone which causes external male genitalia to develop. This happens because the testes contain leydig cells, which respond to lutropin by producing testosterone which drives further male development.
What does genetic transmission explain?
How individuals acquire their sex.
It may also explain some aspects of gender (a person’s sense of whether they are male or female) because of the link between genes and genitalia and hormones.
What are examples of well-recognised atypical sex chromosome patterns?
Klinefelter’s syndrome.
Turner’s syndrome.
How many months after conception is sex organ development complete?
3 months
What is produced by the adrenal glands 3 months after conception?
Lutropin.
In what sex is lutropin produced?
Both sexes.
What is lutropin produced by?
Adrenal glands.
How and why do the testes respond to lutropin?
Testes contain leydig cells which respond to lutropin by producing testosterone. This testosterone drives further male development.
What does lutropin cause the testes to do?
Testes contain leydig cells which respond to lutropin by producing testosterone. This testosterone drives further male development.
How many people does Klinefelter’s syndrome affect?
1 in 10,000 males.
Does Klinefelter’s syndrome affect males or females?
Males.