Download Atypical sex chromosome patterns

Atypical sex chromosome
patterns
Spec check: Atypical sex chromosome patterns: Klinefelter’s syndrome
and Turner’s syndrome
Recap: complete the definitions for the following:
Chromosomes
Hormones
Testosterone
Oestrogen
Oxytocin
These can be seen as examples
of 1 or 2 mark exam questions
What command words would you
expect to see with these questions?
Chromosomes
Hormones
Testosterone
Oestrogen
Oxytocin
23 pairs in humans containing genetic information,
23rd pair determine biological sex: XX for female XY
for male.
Hormones are chemical substances produced in the
body that control and regulate the activity of certain
cells or organs.
A hormone produced mainly in the male testes
(smaller amounts in the female ovaries).
Primary female hormone important in the
development of the menstrual cycle and
reproductive system.
The ‘love’ hormone produced during labour and
stimulates lactation.
Lesson objectives:
-
Identify Atypical sex chromosome patterns
Describe Klinefelter’s syndrome and Turner’s syndrome
Describe and apply the use of animal research within gender research
Evaluate the biological theory of gender development considering the
atypical patterns
Sometimes Abnormal sex differentiation occurs
• Problems with sex differentiation can occur at
any time during development.
• Problems can arise at fertilisation e.g. some
boys have an extra chromosome XXY
• This is known as Klinefelter’s syndrome.
Klinefelter’s syndrome
Klinefelter’s syndrome
• Physical differences
• Underdeveloped genitalia
• Gynaecomastia (enlargement of a man's
breasts)
• Poor language abilities,
• learning difficulties
• ‘Shy and passive’ temperament
Characteristics
•
•
•
•
•
•
•
•
•
an autism diagnosis
an inability to grow facial or body hair
attention difficulties
delayed motor skill development, such as
writing
delayed or difficult speech
delayed or absent puberty
emotional or behavioural issues
gynecomastia, or enlarged breast tissue
hand trembling or involuntary muscle
movements
• hypogonadism, or low
testosterone levels
• hypotonia, or weak muscle
tone
• learning disabilities
• low energy levels
• small penis
• small, undersized testicles
• taller than average height
• weak bones
Girls with XO chromosomes have Turner’s syndrome
Turner’s syndrome
• Physical differences (neck,
stature)
• Underdeveloped ovaries, lack of
menstruation at puberty
• Poor spatial and mathematical
abilities
• Poor social adjustment
Complete the page in your pack… “drawing the syndromes”…
The Role of Hormones
We know:
- Like neurotransmitters, hormones carry messages
- However, the messages are passed much more slowly because hormones travel
in the bloodstream
- They affect numerous processes such as growth, development, mood and
metabolism
endocrine glands, which include the pituitary,
- Hormones are produced by __________
thyroid and adrenal glands
testes
ovaries
- Hormones are also produced by males in the ______and
females in the ______
oestrogen and _____________
progesterone
- The female hormones are ___________
testosterone
androgens
- The male hormones are ____________such
as ________________
• Hormones continue to affect sexual development throughout puberty…………
Hormones and problems in gender development
Some evidence suggests that, when there is a discrepancy between genetic and physical gender,
hormonal problems during pre-natal development may be involved.
o
Androgenital Syndrome occurs when an XX foetus is exposed to excessive amounts of androgens which
masculinise the female foetus and result in the development of male rather than female sex organs. The size of
the penis ranging from being a very over-enlarged clitoris to being a large penis capable of full erection is often
enlarged; however, the testes are usually underdeveloped. The baby will look male but is chromosomally female.
As the brain has been subject to masculinising hormones, these pseudo-hermaphrodites will tend to behave in
more ‘masculine’ ways. The condition can be caused by excessive activity of the mother’s adrenal glands
producing androgens during pregnancy.
o
Androgen Insensitivity Syndrome - aka Testicular Feminising Syndrome - is the result of an XY foetus
becoming feminised by a lack of exposure to male hormones, with the consequence that, even though the
internal female parts have been absorbed, the body tries to develop female sex organs. These pseudohermaphrodites have only a very short vagina and, having no womb, are infertile and cannot menstruate. They
are often taller than most women.
o
However, Daphne Went, famously, was an XY pseudo-hermaphrodite who lived successfully as a woman
despite having a Y chromosome and 2 testes where most women have ovaries. At puberty she did not develop
pubic hair or start to menstruate in spite of developing breasts and female contours as a result of oestregen.
Daphne went on to marry. When she failed to conceive, she consulted her doctor and eventually was presented
with the disturbing facts that she was a he and had no internal female organs. According to E Goldwyn (1979), in
spite of the terrible shock, still felt she was a woman and decided to live as one, she and her husband adopting 2
children.
Daphne is thought to be one of about 500 sufferers in the UK.
• Hormone differences can affect health and lifestyle throughout a person’s life.
• For example – more females develop pain syndromes like fibromyalgia and
they also tend to suffer more from mood disorders such as depression and
anxiety.
• On the other hand, more men than women are likely to develop alcoholism
and to abuse drugs.
Research method check…
A great deal of research into hormones and
gender development is conducted on
animals!
ANIMAL RESEARCH
What do we already know about animal research?
Strengths?
Weaknesses?
• Complete the “issues and debates” hand out
• Highlight arguments FOR animal research
• Identify which are considered practical and which are
considered ethical issues
We can separate these into practical and ethical issues
Practical strengths
- small and can be handled relatively easily
- animals that have a short gestation period and reproductive cycle are
useful because successive generations can be obtained relatively
quickly
- Some animals (e.g. mice) have similar sorts of brain areas and
chromosomal function to humans which is useful for comparative
purposes
- Using animals in research can have practical benefits for the animals
as well as for humans. For example, by knowing more about some
animal species, zoos are able to care for them better.
Ethical strengths
• The main ethical reason for using animals is that procedures can be
carried out on animals that for ethical reasons cannot be carried out on
humans. For example: lesions, which involve damaging brain structure
and ablation, which involves removing part of the brain
• It is argued by some that humans should improve their own quality of
life by whatever means. This is called ‘pro-speciesism’
- Treatments can be developed for humans e.g. anti psychotic drugs
Practical weaknesses
Ethical weaknesses
• Animals are not the same as humans, so there can be problems in
generalising results of studies on animals to humans. Even if an animal
has a similar brain structure to humans it will not be identical
• In laboratory experiments, animals are likely to be confined more
than is normal; they are either in an unfamiliar environment of
bred for the purpose, either of which is unethical
• In order to study some diseases (e.g. Parkinson’s) they have to be
artificially reproduced in animals, which is not the same as a person
developing the disease. Therefore, what is studied might not be
valid
• There is evidence that findings from animal studies cannot be
applied to humans. The drug thalidomide was found to be safe
when tested on rabbits but when pregnant women used it; many
babies were affected by the drug
• Surgical procedures are used, which is likely to cause the animals
pain (or at least discomfort), which again is not very ethical. In
some studies, animals die because of the procedures.
• It is suggested that some species (e.g. insects) do not feel pain,
although this is still being researched
Evaluation of biological explanations for gender development - CASTLES
The results of biological
explanations are based on
tests that can be repeated
e.g. injecting rats with
additional testosterone, or
using MRI scanning in
humans to detect blood
flow. The results are
replicable and can be
shown to be reliable
The theory can be
seen as over simplistic
and that one hormone
is the only explanation
… too simple
Research can bring
about effective gene
therapies to correct
atypical developments
In relation to hormones,
also helps with
applications such as
administrating oxytocin
during childbirth helps
with reducing
haemorrhaging
Case studies demonstrate
that although biologically
gender may be
determined, there are also
environmental influences:
e.g. Simpson et al (2003)
Nature vs Nurture /
Determinism vs Free Will /
Reductionist vs Free Will
Biological Approach!!
PHG digital has additional links that you can
consider:
• Chapter 6….
• Pg 152-153… MALE_VS_FEMALE_BRAIN
• Pg 154-155… http://anthro.palomar.edu/abnormal/abnormal_5.htm
https://prezi.com/shigpmvec3l2/turners-syndrome-vs-klinefelters-syndrome/
Spec check
• The role of chromosomes and hormones (testosterone, oestrogen
and oxytocin) in sex and gender
• Atypical sex chromosome patterns; Kleinfelter’s syndrome and
turner’s Syndrome
Research banks to be
complete… all text books have
research in
Exam style questions on both
sections are in your packs.
Hand outs in pack to help you
with revision:
-
‘Development of sex and gender..’
‘Sasha Laxton’
Mix and match handout
Crossword