Section G1 Introducing genomics
G1.1
From genes to genomes
The history of genetics
Genomics is a branch of the science of genetics which is concerned with
studying all the genes (the genome) of organisms. It is hard to pinpoint an
exact time or investigative work which signalled the start of genetic research
but early work carried out in the 1940s on the role of enzymes (protein
molecules found inside cells) in controlling metabolic pathways (chemical
reactions that take place inside cells) certainly marked a major breakthrough.
This work began to explain the way that enzymes regulate the chemistry of
the cell but also started to reveal the mechanisms which control their
production. In 1953 Francis Crick and James Watson made an important step
in unlocking this mystery when they described the structure of DNA
(deoxyribose nucleic acid). Their work, helped by the studies of Maurice
Wilkins and Rosalind Franklin, helped explain how DNA can encode other
chemicals (mainly proteins, such as enzymes) and how DNA is replicated
during cell division. This was part of the process which led to an explosive
decade of work into the inner workings of the cell. This culminated in a wealth
of information about ideas such as how genes function.
Activity G1.1
A scientific revolution?
The physicist and philosopher of science, Thomas Kuhn, argued that science
goes through two major stages. Most of the time, scientists work within the
current understanding and ideas of a particular problem doing ‘normal
science’. However, every so often, there is major discovery which changes
the way scientists think; this is called a paradigm shift.
In small groups:
1
Draw a time line showing the major developments in genomics.
2
Think about the major scientific ideas you learnt about at GCSE. Which
of those are paradigm shifts? What ideas did they replace and how did the
scientific world change after their discovery?
3
Was the work of Crick and Watson a paradigm shift or a product of
normal science? Try to justify your ideas by referring to the paragraph above
on the history of genetics.
DNA sequencing
DNA uses an ‘alphabet’ of four ‘letters’ (technically called bases) to hold
information. A molecule of DNA is a long string of bases, one after the other.
Reading the bases along a length of DNA is called sequencing. This was first
carried out in the 1970s by Fred Sanger who sequenced the DNA of a
number of viruses and also DNA from mitochondria (small organelles inside
cells involved in respiration). This was followed by work by Paulien Hogeweg
who used complex statistical analysis to develop a method to ‘map’ the
position of genes. Hogeweg’s work was the first example of bioinformatics,
which is primarily the application of maths and computers to examine DNA. It
took until 1995 before the first complete gene sequence for a free-living
organism, the bacterium Haemophilus influenzae, was read; this took place at
The Institute for Genomic Research in the USA. As the methodology
improved, a large number of sequencing studies began to be carried out,
mostly on commercially or scientifically important organisms but also on
endangered species. By 2010, the genomes of more than 2,600 organisms
had been sequenced and the number continues to increase.
Activity G1.2
Genes in the news
Read some reports of recent news stories relating to genomics (these might,
for example, be stories about the impact of genomics on human health, or
sequencing of extinct animals’ genomes). For each one, summarise the main
points using the ‘5W’ headings. That is, you should write notes on the
following points:
What happened? What was done?
Who was involved?
When did this take place?
Where did it take place?
Why did it happen?
Further work
Explore the extent to which ‘the scientific revolution that is genetics’ is a good
label for developments in genetics over the past century. This could form the
basis for a project. Your project is most likely to be successful if you can first
develop a focused question relating to this general area, which you then
explore in depth.
Depending on your research question, you could perhaps start your research
by finding more about what Kuhn meant by a ‘revolution’ and compare his
ideas with those of other philosophers of science (e.g. Karl Popper). You
could also try to find some specific examples of fundamental changes in
people’s thinking about genetics during the past century.
G1.2
Genomics today
The Human Genome Project
In 1990 a project was begun to sequence all of the 3,000,000,000 bases of
DNA that make up the human genome. The Human Genome Project (HGP)
involved collaboration between many research institutes across North
America, Europe and Asia, and published a near-complete version of the
human genome in 2003. The project was hugely expensive, costing around
$3 billion, funding which came from a combination of public and private funds
and, described as a ‘mega project’ was one of the largest scientific
investigations ever undertaken. The DNA used in the project came from a
small number of donors and it was not until 2007 that the DNA from an
individual person was completely sequenced.
Ethical, legal and social issues
The HGP was not just focused on sequencing genes; it also addressed legal,
ethical and social issues surrounding genomic studies. Although much of the
HGP work has been praised, there are ongoing concerns about research into
genetic variation between populations (the ‘Human Genetic Diversity Project’,
or HGDP). Debra Harry, who heads the US group on the Indigenous Peoples
Council on Biocolonialism, has been a major critic. She argues that the HGDP
has focused too much on the rights of individuals whereas, in some cultures,
for example tribal, there is a much greater emphasis on group decision
making and that this makes the guidelines set down by the HGDP
problematic. For example, ethical guidelines might address the need to ask
an individual to give their ‘informed consent’ before they take part in a
genomic study, but neglect to seek for informed consent from a tribal group.
Where now with genomics?
The possibilities of what can be done with genomic information seem endless
and many of these ideas are the focus of the subsequent lessons in this
sequence. As an example, in January 2008 the 1000 Genomes Project was
launched, which is designed to produce a database of genetic variation. The
main aim of the project is to document genetic variations, to help researchers
identify those involved in disease or give protection from disease. In October
2010, in the scientific publication Nature, the 1000 Genomes Project
announced it had successfully sequenced 1000 human genomes.
Activity G1.3
Money well spent?
Scientific research can be very expensive and, especially with projects that
take many years to complete, costs often spiral. It cost around $3 billion
dollars to complete the HGP. For comparison, the British Defence Budget for
2010/11 was around $23 billion dollars.
List what you consider the pros and cons of spending money on the HGP and
other scientific research of this type. Then decide whether you think the HGP
was money well spent, and write a short paragraph to summarise your
reasons.
Activity G1.4
Is all knowledge good knowledge?
The science of genomics has brought many benefits but also raises a number
of important ethical and social issue questions.
In a group of four to six, discuss Debra Harry’s comments.
As a group, make a list of the points for and against her ideas and then split
into two smaller teams.
One team should defend the position of the HGDP as being concerned with
individual rights, the other should argue from the point of view of group rights
as being of greatest importance.
Open your discussions out to the whole class.
Further work
Write a reasoned response to the question ‘The HGP: was it worth it?’
Present some evidence and arguments that support your own point of view,
and try also to include some counter-arguments and your responses to them.
Section G2 Genetic information
G2.1Genetic disorders and choice
What are genetic disorders?
Genetic disorders are illnesses or diseases caused by changes to an
individual’s DNA. How such changes can cause disease is often complex but
diseases of this type fall into two broad categories: those due to changes in a
single gene and those which are multifactorial. As the name suggests, a
single gene disorder is the result of a single mutated (altered) gene; these
can be dominant genes, as in Huntington’s disease, or recessive, as in cystic
fibrosis. A multifactorial disease is the result of a combination of one or more
genes and environmental factors; for example hypertension (high blood
pressure) or diabetes. Research in this field is difficult and time consuming
but, in recent years, great advances have been made in identifying the genes
involved and understanding how the changes cause disease.
In the first activity you are going to focus on a single gene disorder associated
with a heart abnormality and consider what choices are available to people
when they know they, or members of their family, carry an abnormal gene.
Activity G2.1
Would you want to know?
As research into genetic disorders advances, it is becoming easier to detect
abnormal genes related to specific diseases.
In small groups, discuss the following questions.
1
Would you want to know if you had a single gene disorder that
predisposes you to problems with your heart, including heart attacks?
2
What options would you have if you learned this?
Activity G2.2
Long QT: a single gene disorder
Long QT is a rare, inherited, single gene disorder which, left untreated, can
lead to rapid heartbeats, blackouts and even sudden death.
Watch the film about a heart condition called long QT and then do the
following:
1
Write your own brief summary of the different responses the people in
the film had regarding whether or not they wanted to know if they carried the
gene associated with long QT.
2
Using the point of view/argument/counter-argument framework explore
the rationale behind their decisions and the decisions you came to during
Activity G2.1.
Eczema: a multifactorial disorder
Not all genetic disorders are as harmful as Long QT. For example, malepattern baldness, while sometimes distressing, is not life-threatening.
However, as healthcare improves and more is understood about disease
detection, diagnosis and treatments, much more can be done to help. A good
example is eczema, a condition of the skin, caused by a combination of
genetic factors and the environment.
Activity G2.3
Eczema: a multifactorial disorder
As you watch the film about studies in eczema, makes some notes about the
techniques used to identify the genes involved in this disorder.
After watching the film, discuss the following in small groups:
1
How are case-control studies and genome-wide association studies
(GWAS) carried out? What are the similarities and differences between these
studies?
2
Why is it so difficult to make predictions about this type of genetic
disorder?
Further work
Research one of the following questions and write a short report:
1
Should people whose families have a history of genetic disorders seek
genetic testing themselves?
2
If individuals were given information about disease-linked genetic
variants, what support should be offered to them?
Divide the research, and your report, into two parts. One part should focus on
finding out some facts relating to the question, which you report in a Literature
Review. The other part should be where you develop your own ideas and
present arguments relating to your own point of view under the heading
Discussion.
This work could be the starting point for your project – but you would first
need to develop a focused research question that you could explore in depth.
For example, you could choose one particular genetic disease, research it in
detail, and explore a question relating to its diagnosis or treatment.
G2.2
Is it better to know or not know?
What is genetic testing?
Genetic tests can identify changes in DNA which may be associated with a
disease, or have some other impact on an individual’s health. This novel
technology has many applications, including, for example, the screening of
embryos in IVF treatment and screening newborn babies for genetic disorders
such as phenylketonuria. A fast growing branch of genetic testing is carrier
screening which involves screening an individual for a version of a gene
(allele), which, if two copies were present, would cause a genetic disorder. In
the previous lesson, you considered the implications of knowing whether or
not you carried genes associated with single gene or multifactorial diseases.
In this lesson, you are going to examine some further questions about what
we should personally do with information about our genes and who should
have access to this information.
Activity G2.4
Dealing with uncertainty
Watch the film about a family talking about the risk of breast cancer and then,
in small groups, do the following:
1
Discuss what you would have done if you were in the same position as
the family in the film and compare the actions of the uncle compared to his
nieces.
2
Justify the choices you have made in Question 1.
Genome-wide association studies
Genome-wide association studies (GWAS) involve comparing the genomes of
people with a particular characteristic (which could include illness, such as
cancer, coronary heart disease or diabetes) to the genomes of a control group
(such as unaffected individuals) and then searching for changes in the
genome which are associated with the characteristic. As more of these tests
are carried out, it is becoming clear that the genetics of disease is very
complex and it is rare to find a disease that is caused by a simple genetic
variant. As you saw from the film about breast cancer, this means that even
when tested, there can still be a great deal of uncertainty about the likelihood
of developing the disease and this means making decisions about what to do
is even harder.
Activity G2.5
Genome-wide association studies
Watch the film about genome-wide association studies and then, in small
groups, discuss the following:
1
Why is there still uncertainty about many diseases that have a genetic
component?
2
What are the benefits and problems associated with large-scale
genome-wide surveys?
The ethics of genomic studies
In order to get large sample sizes for comparisons of genomes, many
countries have set up biobanks which are repositories of, amongst other
things, genetic material (obtained from blood samples). Donations may be
made anonymously with no record of the owner of the genetic material being
made – but this means that individuals could not find out the specifics of their
genome. However, for studies like the UK Biobank, it is necessary to link DNA
information to clinical information, so anonymity isn’t possible. However,
samples are anonymised before they are used by researchers, to protect
individuals’ privacy. There would therefore be the possibility for individuals to
find out about their genome, but it is general policy not to give feedback to
participants. This raises particular ethical questions which you will explore in
Activity G2.6.
Activity G2.6
The ethics of biobanks
Watch the film about the ethics of biobanks and then, in small groups, do the
following:
1
Discuss the ethical questions that Professor Michael Reiss raises. In
your discussion refer to one or more of the common ethical frameworks (e.g.
utilitarianism, rights and duties).
2
Discuss whether you would want to know if you carried genes associated
with a specific disorder. You might want to discuss the issues of consent to
research and use of genetic information.
Further work
A question about biobanks and related ethical issues could be a good starting
point for your project.
G2.3
What does risk mean?
Life is risky
In the previous lessons you started to look at the genetics involved in certain
medical conditions. Genomic studies of this type always discuss ideas of risk
surrounding genes and disease, but risk is a difficult idea to understand. The
idea of risk is wrapped up in mathematical modelling and statistical analysis
(this is the way insurance policies are developed). However, on a day-to-day
basis we can understand risk as being a combination of the probability (or
likelihood) of something occurring and the impact it will have upon us, and
possibly those around us. For example, the probability of crashing in an
aeroplane is very small but the impact (almost certain death) is huge, while
the probability of catching a cold during the winter is high but the impact will
probably be fairly low.
Activity G2.7
A risky day?
1
Make a list of the activities you did from waking up this morning to
arriving at this lesson.
2
Rank the list in order of those things you think are highest risk
(remember, the combination of probability and impact) down to those of
lowest risk.
3
Compare your lists with those of other students. Does anything
interesting strike you from the lists and the ranking activity?
Activity G2.8
Risk and genetic diseases
You have already seen that in many cases the genetics of disease is
complex. For a particular condition, there may be many genes involved, some
of which interact with one another, as well as influences from the
environment. Added to this is the idea that, even if you are screened for, and
found to carry, certain genetic variants, you will need to consider the
seriousness of the risk of developing the condition.
Watch a short film clip about risk and genetic disease. Whilst you are doing
this, make some notes about the points of view of the experts involved in the
discussion.
A good example of screening and risk is provided by porphyria disorders, a
series of disorders affecting the way the body produces the blood protein,
haemoglobin. Acute porphyria causes a range of symptoms, including
abdominal pain, vomiting and diarrhoea and mental illness. A famous sufferer
of acute porphyria was King George III, whom people thought was mad.
Acute intermittent porphyria is dominantly inherited, meaning you only need
one copy of the genetic variant for the disease to develop. This seems pretty
straightforward; if you have the variant, you are going to develop the disease.
However, the actual risk of it developing is much more complex, especially
because several external factors are known to be involved (including
infectious illness and certain types of drug). So, the presence of the variant
does not necessarily mean the disease develops and the impact of the
disease can be very different between individuals. Also, some people might
not want to know if they carry the variant anyway.
Activity G2.9
Who should make decisions about risk?
In the film, you heard about ideas of ethics and citizenship surrounding risk
and genetic disease. One of the experts suggested that individuals should
have the right to make decisions based on their weighing up of the risks while
the other experts argued that, ultimately, it should be the responsibility of the
state to make these decisions.
1
Think back to Activity G2.7 (Question 2) and consider the top three risky
things you have done today. For these things, write a paragraph describing
the choices you were faced with and how you came to the decisions you did.
2
Write notes on your own responses to the questions below, then
compare your responses with someone else.
(a) Who do you think should be responsible for making decisions about risk
and genetic disease?
(b) What position should the state take? What is the responsibility of
individuals?
(c) How would you decide whether you would be screened for a genetic
disease?
(d) Would you want to go to your GP or would you be happy to do this via an
internet-based company?
Further work
Might there be an evolutionary advantage to taking risks, or is it more
advantageous to be cautious?
Discuss this question in a small group. Do you think it is possible to give a
definite answer (‘yes’ or ‘no’)? What evidence would you try to gather that
might help you answer the question?
G2.4
Personalised medicine
What is personalised medicine?
Medicine is the science and, in some ways, art of healing people. This can
mean preventative interventions (such as vaccination) but also helping people
in the wider sense, for example providing emotional support during difficult
periods in people’s lives. In the past, drug development relied on observations
of the general effectiveness of treatment, for example seeing that antibiotics
kill certain microbes, and then drug trials on non-human animals and
eventually humans. With the development of genomics, there are now drugs,
and other treatments, that are tailored to individual requirements, as
determined by our genes. Potentially, this has many benefits because it
means people can receive treatment that is designed to take into account how
their body works and responds.
Activity G2.10
The role of medicine
The role of medicine might, at first, seem obvious: something like ‘to make
people well’. But, when you start to consider it more carefully, the definition
becomes more complex.
1
Make a list of things that you think can be described as ‘medicine’ Your
list might include particular actions, treatments, drugs ...
2
Contribute your ideas to a list compiled by the whole class. Be prepared
to challenge other people’s contributions, and to defend your own.
Activity G2.11
The potential of personalised medicine
Watch the clip of four experts on genetics discussing the science of, and
issues surrounding, personalised medicine. Then read the information below.
Being able to treat people in specifically designed ways could be very
beneficial. An area of exciting research in this field is pharmacogenetics.
This is the study of how variations in genes cause differing responses to drug
therapies. A good example is a study of the effects of warfarin, a drug that
thins the blood and is used to treat people with various heart conditions.
Identification of the genes involved in the metabolism of the drug has led to a
much greater understanding about how it works and the doses that people
should be given, although using this information is difficult in practice.
Another example of pharmacogenetics is in the identification and treatment of
some types of cancer (e.g. breast cancer) where, by locating specific genetic
changes in the tumour, the right drug for that patient can be chosen. (Note
that it’s the changes in the tumour’s DNA that are important, not the person’s
constitutional DNA.) Here, the right choice of treatment based on genetic
information can dramatically affect the outcome.
Concerns about personalised medicine
Pharmaceutical companies are looking to develop drugs that will only be
effective for people with certain biomarkers, defined by the NHS as “a
characteristic that is objectively measured and evaluated as an indicator of
normal biologic processes, pathogenic processes, or pharmacologic
responses to a therapeutic intervention” and usually referring to the presence
of specific molecules. The concern is that if drugs are developed that can
help only some people affected by a condition, this might it lead to greater
inequalities in treatment.
A further problem associated with a personalised approach to medicine is that
it requires genetic testing and the problems associated with the information
that is collected. If this information remains private between doctor and
patient, there is probably little to worry about, but there are fears that it could
be made available to groups such as insurance companies and employers.
Another concern is that genetic testing is now becoming widely available,
currently on the Internet, but potentially, one day, on the High Street. This
means that the general public can obtain genetic screening which may give
them information that looks worrying, but there is no support system to put the
information in context or advise them what to do. Even your GP is unlikely to
be able to help, as interpreting the information requires specialist knowledge
of a highly complex area. Actually, in many cases, the test results contain little
useful information, and experts tend to refer to them as ‘genetic horoscopes’.
There is a risk that the tests simply increase anxiety about health.
Activity G2.12
Healthcare by the mail
Most genetic testing kits you can buy are available only through the internet.
They normally involve you sending a sample of saliva (which contains cheek
cells) through the mail to a laboratory where tests are carried out to screen for
genetic variants associated with certain diseases. This is very different from
the traditional doctor-patient relationship, and many healthcare professionals
are concerned about the implications, though some would argue that it is
empowering to know the risks you face.
1
On your own, imagine you had just received some bad news. Think
about what you would do, and who you would talk to. How would you decide
what plan of action to take?
2
With another student, discuss your responses to this first question and
then widen your discussion to consider the impact of genetic testing (both via
doctors and internet-based companies) on (a) individuals (b) society in
general (c) the NHS.
3
Then join with another pair of students to make a group of 4 and
compare your ideas about Question 2.
Further work
Discuss the question ‘Should the NHS provide personalised health care?’ Try
to consider the question from various angles, e.g. ethical, economic.
Section G3 Genes and behaviour
G3.1
Breeding a better future?
Eugenics: a brief history
Eugenics is the name given to the application of the branch of genetics that
seeks to improve the genetic composition of a population, most often the
human population. The term was coined by the scientist Francis Galton, halfcousin of Charles Darwin. Galton worried that a society that supports the
“underprivileged and weak” is at odds with natural selection and, instead of
improving, will show “reversion towards mediocrity”. He researched his ideas
by developing complex statistical analyses which he used to investigate the
inheritance of multifactorial traits such as height and strength.
Through time, the term eugenics came to represent an idea of human
improvement (positive eugenics), sometimes linked with the concept of Social
Darwinism: the idea that selection can lead to a ‘better’ human population.
This way of thinking had strong support from some influential people including
Winston Churchill and William Beveridge who argued that careful marriage
counselling could lead to an improved population. Nazi Germany of the 1930s
and 1940s developed the ideas of eugenics by carrying out mass sterilisation
of people they perceived as ‘undesirable’; this idea about a ‘pure race’
culminated in mass murder.
Activity G3.1
Are there any benefits to eugenics?
In small groups, discuss the following questions.
1
Why do you think eugenics gained support from people such as
Churchill and Beveridge?
2
Galton used complex statistics to develop his arguments while, at the
same time, biologists were arguing that studies of this type needed to include
biological ideas of behaviour and nurture. Mathematical modelling of complex
situations can be very useful, but almost inevitably the models are imperfect.
From your studies of science, try to think of other examples where complex
situations have been modelled mathematically, and where interpretation of
the models has been controversial.
Eugenics after the Nazis
After the atrocities of World War II, eugenics was seen as murderous and
poor science; however, this does not mean that its practices were stopped. As
late as 1972, immigrants arriving in Canada were subject to an IQ test
(something that those with poor English language skills could not do). People
‘failing’ the test were then offered the choice of sterilisation or barred entry. In
Sweden, until 1975, a total of around 65,000 people were forcibly sterilised
because they were determined to be ‘mentally unfit’.
Selective breeding has been used since prehistoric times to modify farm
animals and crop plants. More recently, this has included the use of genetic
engineering techniques when these became available. It has been argued
that because the Human Genome Project would open the door on the
possibility of finding genes that are associated with undesirable
characteristics, there might be opportunities to eliminate harmful genes. In
addition to this, in 1980 in the US a ‘genius sperm bank’ was opened where
intellectuals of the time were encouraged to donate sperm to be used in IVF
treatment. By the time the project was abandoned in 1999, over 220 children
had been conceived.
People have suggested that techniques such as preimplantation genetic
diagnosis (PGD) which involves screening of IVF embryos, are verging on
eugenic, in that they involve some sort of selection. But this is individuals
deciding, not the state decreeing. Even so, there are some tricky issues: is it
OK to select to prevent a child being born with DMD? Cystic fibrosis? Lateonset cancer? A cancer that might or might not develop? Deafness? What
message does this send to people with those conditions?
Analysis of free fetal DNA from the maternal circulation is also going to raise
challenging issues about screening healthy pregnancies. This so-called
ffDNA screening bypasses the need for amniocentesis, thus avoiding risk to
the mother or fetus, so it could be in great demand.
Activity G3.2
Changing language
By the 1980s the term ‘eugenics’ was rarely used and terms such as ‘genetic
modification’ or ‘enhancement’ were becoming more common, though in a
quite different context.
Look up all three of these terms in a dictionary and compare the definitions.
What does the story of the use of the term ‘eugenics’ tell you about the
importance of language in terms of the scientific community and the general
population? Discuss your ideas with another student.
Activity G3.3
Eugenics today
In a small group:
1
Brainstorm your ideas about human characteristics you feel are
‘undesirable’ and worth trying to remove from the population. For each one,
consider the criteria you used to reach a decision.
2
Do you think it is right to try to attempt to remove ‘undesirable’
characteristics? Use one or more ethical frameworks (e.g. utilitarianism, virtue
ethics) to help with your discussion.
3
In 2011, the state of North Carolina, USA, apologised to thousands of
people who had been forcibly sterilised during the mid 20th century in an
attempt to improve the population. Use the internet to find out more. You
could start with these sites:
http://www.bbc.co.uk/news/world-us-canada-13700490
http://www.youtube.com/watch?v=BE5bF5DMEhQ
Write a short account of what you find out. You might find it helpful to use the
5W framework (see Lesson G1.1).
Further work
Find out more about Galton and his ideas. Visit these websites:
http://galton.org/
http://www.eugenics-watch.com/roots/chap02.html
http://www.bbc.co.uk/news/magazine-13775520
G3.2
Natural born criminals?
Multiple copies of chromosomes
One area of extensive genetic study has been into the effect of multiple
chromosome copies, particularly disorders involving the sex chromosomes.
Normally, humans have 23 pairs of chromosomes: 22 pairs of autosomes
and one pair of sex chromosomes. Usually females have two copies of an X
chromosome while males have an X and a Y chromosome. The Y
chromosome has few functional genes. Sometimes, during the formation of
sperm and eggs cells (gametes), the chromosomes do not separate properly,
a mistake called non-disjunction. In the case of non-disjunction of the sex
chromosomes, the result can be a gamete containing two copies of a sex
chromosome and another containing none. An embryo formed from the
fertilisation of gametes of this type may have a variety of sex chromosome
disorders; for example, X0 (only one sex chromosome present), XXX, XXY or
XYY.
Genetics of the prison population
A popular area of research has been into possible genetic predisposition to
criminal behaviour. Studies of the number and appearance of chromosomes
(the karyotype) of prisoners were extensively carried out in the 1960s and
70s in the hope that particular genetic constitutions might be found that could
predict criminal behaviour; something that could maybe act as a warning sign
in children so appropriate action could be taken.
The Y chromosome is responsible for causing a massive increase in the
production of testosterone in the developing fetus, something which results in
the (initially female) fetus becoming male. For this reason, the Y chromosome
has been thought of as being important in explaining certain ‘male type’
behaviours (for example, aggression) and consequently, an extensively
researched theory has focused on whether or not the prison population is
over-represented with men with XYY sex chromosomes.
About 1 in 1,000 baby boys are born with XYY sex chromosomes. These
babies look normal and have very few differences to XY males. XYY males
grow normally and are usually fertile, and most are never being diagnosed.
However, studies in the 1960s found that the proportion of XYY males was
ten times higher in the prison population than in the non-prison population.
This led to newspaper reports of so-called “super males” who were
aggressive and prone to criminal behaviour. Also, studies of patients in
hospitals for the mentally ill found similar patterns, with XYY males being
described as having a greater tendency toward psychotic behaviour. These
observations were quickly embraced by parts of the scientific community and
even more readily by the general public and came to the forefront in the US
when an infamous mass murderer, Richard Speck, stated he was a “victim” of
XYY. This announcement was quickly followed by feature articles in the New
York Times and Newsweek
By the end of the 1960s, some scientists were beginning to challenge these
findings, particularly regarding the validity of the research methods used in
the studies. A major criticism was that the research was not careful enough in
how the people involved were chosen. This problem, often called selectionbias, is sometimes seen in social science experiments where the research
focuses on a specific group but tries to then draw generalisations which are
too broad or very weak. It has become quite clear that XYY men are not born
criminals, and the great majority are leading normal lives.
Activity G3.4
Views about criminals and mental health
In small groups, discuss the following question.
Why do you think newspapers were so quick to pick up on the research
findings of the 1960s studies into the genotypes of criminals and the mentally
ill and yet, as it happens, to have been less eager to report the problems
associated with the studies?
Activity G3.5
Researching populations
Imagine you are designing a research study comparing the genes associated
with violent behaviour of the prison population with that of the normal, nonprison population.
Make a list of the data you would want to gather.
How would ensure your findings were valid?
What difficulties might you face with research of this kind?
Activity G3.6
My genes made me do it
In a small group, or working in pairs, discuss whether you think that ‘my genes
made me do it’ is a good excuse for bad behaviour. In your discussion you
might consider the following questions:
1
Does having a certain genetic make-up inevitably lead to antisocial or
criminal behaviour?
2
How does the idea of genetically influenced behaviour relate to the idea
of free will?
3
Suppose behaviour regarded as ‘good’ (e.g. kindness, generosity) is also
influenced by our genes. Should people be praised and rewarded for ‘good’
actions?
G3.3
Researching genetics and behaviour
What is behaviour?
In the next two lessons you will discuss the role that genetics has in
explaining some types of human behaviour, but in this lesson the focus is first
on research into behaviour of non-human animals. Studies of this type are
interesting in their own right but also because they can provide insight into
some types of human behaviour. Just as in humans, some non-human
animals show a combination of innate behaviour (instinct) and learned
behaviour. Three of the most important researchers into animal behaviour
were Ivan Pavlov, B.F. Skinner and Konrad Lorenz. Both Pavlov and Skinner
worked on a type of learning called conditioning. Here, animals can be
trained to perform tasks or give specific responses through association with a
reward. For example, using food as a reward, Skinner trained animals to
press buttons of certain colours in certain sequences. Lorenz’s work focused
on instinct, particularly in birds; in his experiments Lorenz’s imprinted his
‘image’ on goslings (goose chicks) which then followed him as they would
their mother.
Activity G3.7
Behaviour and reward
Thinking about the experiments you have just read about, in small groups
discuss the following:
Skinner trained animals via a reward system. How could a system like this
operate in natural situations in the wild?
The kittens and the voles
Kittens
In the 1960s, a team of neuroscientists working at Harvard University made
an important discovery. While investigating how the brain interprets
information from the eyes, they found that there are different families of
neurons (nerve cells) in the visual cortex (the part of the brain involved in
vision) that respond to the orientation of objects. This means that when we
see, the different neurons ‘fire’ as different shapes come into our field of sight.
The discovery that there are ‘orientation sensing’ neurons led to work
investigating the role that the environment plays in the development of the
brain.
In a now famous experiment, a team at Cambridge University worked with
kittens to determine how the brain becomes wired up during the first few
months of life, the so-called critical period. The team took day-old kittens
and raised them in them in environments that were painted with either vertical
or horizontal stripes; after a few weeks, the kittens were then tested.
Astonishingly, when presented with a fishing rod toy, the kittens that had been
raised in the vertical stripe environment only responded when the rod was
moving in a vertical direction, while the opposite was observed in the kittens
from the horizontal environment. So what does this mean? The absence of
expected kitten behaviour suggested that the environment had affected the
development of the brain. When physiological studies were carried out, it was
found that the kittens were missing certain types of the vital orientationsensing neuron.
How does this relate to genetics and behaviour? While the instructions for the
development of the brain are written into nerve cells, the way the brain
develops is also heavily dependent on environmental inputs.
Voles
A male meadow vole (a small, mouse-like animal), like many small mammals,
mates with as many females as it can (polygyny) and shows no kind of
paternal care to its many offspring. Interestingly, there is one species of vole,
the prairie vole which mates with one female for life (monogyny). This
observation has intrigued biologists for many years. In 2006, a possible
explanation was found. Researchers found that the promiscuous voles had
fewer receptors in their brains that are sensitive to the hormone called
vasopressin. In contrast, the brains of prairie voles are packed with these
receptors. Vasopressin is released during sex and the scientists showed that
the presence of vasopressin on the receptors appeared to lead to rewarding
sensations; something which bonded the prairie voles in monogyny. Due to
the lower number of receptors, meadow voles don’t appear to get the
sensations and so move on to mate with another female. The really
sophisticated part of the study came when meadow voles with injected with
large amounts of vasopressin and, as you might expect, they became
monogynous.
What do these two stories tell us? On one hand, they are intriguing bits of
science but their implications for humans are also fascinating. The work on
voles may have wider applications to studies of people with autism. One
hypothesis is that people with autism have lower levels of vasopressin
receptors (compared to the population as a whole) and this could partly
explain some of their difficulties with social relationships.
Activity G3.8
The ethics of animal research
You have seen how some of the applications of research with non-human
animals might be applicable to human studies. However, these studies often
involve invasive methods (such as brain surgery) or force animals to live in
unnatural environments (such as the kittens – their stripy environments were
actually drainpipes).
In small groups, discuss the following:
1
When is research using non-human animals justified? (Refer to one or
more ethical frameworks.)
2
Does the type of research and the animals involved (for example, rat vs.
invertebrate vs. vertebrate) make a difference? Why do you think that?
The twin problem
In his 1875 book Inquiries into Human Faculty and its Development, Francis
Galton wrote:
Twins have a special claim upon our attention; it is, that their
history affords means of distinguishing between the effects of
tendencies received at birth, and those that were imposed by the
special circumstances of their after lives.
Since then, human twins have been a favourite subject of research for
geneticists. Twin studies have been involved in a range of research including
intelligence and aggression, and schizophrenia and alcohol dependence.
Classic twin studies involve research into children who have been raised in
the same environment (i.e. the same home), often with comparisons made
between identical twins (those formed from one egg and thus genetically
identical) and non-identical twins (those formed from separate eggs and no
more genetically similar than brothers or sisters). The non-identical twins
provide a control, meaning this type of comparison allows the effect of
environmental and hereditary factors to be disentangled. These types of study
make a series of assumptions, the most important being that identical and
non-identical twins share equal environments to the same extent. Despite
these problems, a huge amount has been learnt from twin studies and
methodologies continue to be refined and improved. If nothing else, twins
provide a ‘control’ in human-based experiments which is not normally
possible.
Activity G3.9
The twin problem
There is a concern that parents of identical and non-identical twins may not
treat them in the same way meaning they would not be raised in equal
environments. This problem could undermine twin studies.
In small groups, discuss the following:
1
Do parents and teachers treat identical twins in the same way they treat
non-identical twins? If not, why could it matter to the studies?
2
Is it ethically acceptable to carry out twin studies? Can you think of any
objections to work of this type? Use one or more ethical frameworks to guide
your thinking.
G3.4
All in the mind
What is mental illness?
The term mental illness covers a range of different psychological disorders
that affect personality and behaviour and can cause distress and disability,
interfering with normal functioning. Some illnesses of this type are very mild
and cause little problem, for example mild compulsive disorders, while others
can be extremely debilitating or even make the individual dangerous to
themselves or others. Diagnosis of mental illness can be difficult and often
involves psychological testing and diagnostic interviews but it is thought that
up to a third of those with mental health conditions are never diagnosed. The
stigma associated with mental illness has meant that people who experience
psychological disorder are often judged or devalued by society. Many people
used to feel that the mentally ill were to blame for their conditions or that they
should be locked away. This attitude was epitomised by the Bedlam Hospital
in London which was established in the 1600s as a ‘human zoo’ where
patients were paraded for the pleasure of a curious public. Even as recently
as 2003, attitudes to mental illness were betrayed by The Sun’s hugely
controversial headline about the boxer Frank Bruno, which read, “Bonkers
Bruno Locked Up”. (The paper later changed the headline to “Sad Bruno in
Mental Health Home” and adjusted the accompanying story to describe Bruno
as a “hero”.)
Activity G3.10
What is mental illness?
Use library and internet resources to research the ways that mental health
and disability issues are reported.
In the sources that you consult, look for examples of fact, opinion and
speculation. Also comment on whether the sources are likely to be reliable,
incomplete or biased.
Genes and mental illness
Schizophrenia
Schizophrenia is a mental disorder characterised by abnormalities with
mental processing. People with this condition often have hallucinations
(hearing voices or seeing things that aren’t real) and can often be paranoid
(believe they are being persecuted). They therefore often find social
interactions difficult. Diagnosis is not easy and has normally relied on patients
explaining their experiences and a doctor then conducting a psychological
profile. The illness is sometimes linked with the brain having problems
processing the hormone dopamine and in such cases can be treated with
drugs that interact with this system.
Recent genomic research has focused on looking for genetic variants
associated with patients with schizophrenia. Twin and genome wide
association studies have revealed that specific regions of chromosome 6 and
a variant in a particular protein called 804A are associated with the illness, but
the influence of the environment is also important, especially in triggering the
illness to develop. Studies suggest that even if people are found to have two
copies of the 804A variant, they are at no more than 1-2% risk of developing
the illness and so it is not a particularly useful predictive indicator.
Attention deficit hyperactivity disorder (ADHD)
ADHD is a psychological disorder characterised by a range of symptoms, the
most obvious being hyperactivity. The condition is much more common in
boys and, until quite recently, was not properly recognised as a form of
mental illness, but just put down to ‘naughty behaviour’. As with
schizophrenia, ADHD may be linked with problems in the brain detecting
dopamine and drug therapy has been found to be beneficial, as have other
treatments. Twin studies have indicated there is a strong correlation between
the condition and dopamine production and control but several environmental
factors, such as nicotine absorption by the developing embryo and the food
preservative sodium benzoate, have also been shown to be contributory
factors in some cases.
Genetic determinism
Both these cases call into question the nature-nurture debate. That is, how
many of our characteristics are determined by our genes (nature) and how
many by the environment (nurture)? It is clear that some characteristics are
controlled entirely by genes, for example blood grouping and eye colour; the
term trait is often used specifically for such characteristics. However, when it
comes to behavioural characteristics, the situation is much more complex. It is
important to avoid genetic determinism – that is, supposing that your health
and your fate are inescapably fixed by the genes you were born with. As we
have seen, both schizophrenia and ADHD can be influenced by the
environment, and the interplay between genes and outside experiences is
complex. Because of this it is difficult to unravel how genes and the
environment influence one another and this is one of the main reasons why
this area of genetics is particularly exciting.
Activity G3.11
The nature-nurture debate
In small groups, discuss the following:
1
Some people have argued that complex characteristics such as
intelligence are not actually traits and that to describe them as such is
misleading. What do you think?
2
There is an argument that too much weight has been placed on genetic
determinism and that this has undertones of eugenics, ‘genetic discrimination’
and racism. Do you agree?
Further work
Choose one mental illness (e.g. schizophrenia, ADHD, bipolar disorder) and
research the extent to which it is genetic in origin. You could also explore
questions relating to its diagnosis and treatment.
G3.5
Addiction
What is addiction?
In this lesson you will continue to think about the role that genes and the
environment play in determining our behaviour. The focus is on addiction and
you will look at two specific examples, alcohol and food. Addiction means
having a need for something which, if the need is not met, causes
psychological problems. Until fairly recently the term addiction was reserved
for drugs (normally called substance addiction) but has now been widen to
encompass things such as shopping, sex and gambling (behavioural
addiction).
Activity G3.12
What is addition?
In small groups:
1
of.
Make a list of all the different type of behavioural addiction you can think
2
Are there any characteristics that link the addictions you have listed?
3
Try and rank your list in order of how potentially damaging each
addiction could be.
Alcohol and obesity
Alcohol
Addiction to alcohol is normally called alcohol dependency or alcoholism.
However, a far greater number of people are defined as suffering from
alcohol abuse. The main difference between these terms is that dependency
on alcohol is normally associated with withdrawal symptoms if the drug is
removed, something not seen in alcohol abuse. The mechanisms that
underpin alcoholism are widespread and encompass both environmental and
genetic factors. Studies have shown that there are genes that can predispose
people to alcoholism. Stress in both childhood and adulthood is also
important, as is children mimicking the behaviour of their parents.
Different ethnic groups show differing degrees of tolerance to alcohol and it
has been suggested that variation in a specific gene (the alcohol
dehydrogenase gene [ADH]) involved in alcohol metabolism may be
involved in addiction. For example, some individuals with a certain ADH
variant are less likely to develop alcohol dependency; this variant is more
common in the Asian population, so Asians appear less likely to develop
alcohol dependency. In addition, as with many psychological disorders, genes
that control the production and detection of dopamine in the brain have also
been linked with alcohol dependency.
Obesity
There are many factors that can lead to excessive weight gain (obesity) but
an important one is the interaction between specific genes and the
environment. The genetics of this condition are complex but a variant of the
FTO gene (Fat mass and Obesity associated gene) has been found to play
an important part, with people who have two copies tending to be heavier
than those with only one (or none). Twin studies have identified a high degree
of heritability in weight – almost as great as with height. The situation is
further complicated because there are certain genes associated with
controlling appetite whilst others regulate metabolism, and interaction
between them is not well understood. Weight control is linked to energy
balance and depends on intake and usage. The picture is a complicated one.
What is much clearer it that some ethnic groups show a much greater
propensity for weight gain and this may have an evolutionary basis. For
example, when exposed to high-fat modern diets, the Pima Native Americans
of southern USA quickly put on weight and developed diabetes. This may
reflect an adaptation to a low-calorie diet, as their ancestors lived in regions
where food was scarce so storing fat could have been advantageous.
Activity G3.13
An individual’s problem or one for society?
In small groups, discuss the following:
1
Alcohol dependency and obesity contribute to many medical conditions,
treatment of which costs the NHS large amounts of money. Discuss the views
of those in your group about whether illness caused by addictive behaviour
should be treated on the NHS.
2
Studies on non-human animals have shown these tend not become
overweight; the only exception is in pets. What do these observations tell you
about the difference between humans and other animals?
3
Environmental influences play an important role in addictive behaviour.
Consider the way food advertisers target certain groups of people. What are
your opinions about this?
Further work
The discussions in Activity G3.13 could provide fruitful starting points for
project work. For example, possible research questions might be:
1
Does advertising play a role in creating behavioural addiction?
2
Should the NHS be responsible for treating behavioural addiction?
Section G4 Genomes, evolution and breeding
G4.1‘The Ascent of Man’
Human origins
In his 1973 BBC series, The Ascent of Man, Jacob Bronowski described the
journey of human evolution from the Rift Valley in Ethiopia to the latest
developments in neuroscience, a story that covered over two million years
and explained the remarkable feats that humans have achieved. The series
was filmed at time of great excitement in biology when the first attempts at
genetic engineering had just proved successful, and health care based on
genomic studies was starting to seem possible. What do such studies tell us
about our past and about what our future might be?
Activity G4.1
Human origins
Studies of the evolution of humans have been extensive and the fossil record
has been a particularly rich source. In recent times, analysis of human
genetics has helped shed more light on our origins and relationship with other
living things.
In small groups, discuss the following questions:
1
Look at Haeckel’s ‘Tree of Humanity’:
http://upload.wikimedia.org/wikipedia/commons/b/b9/Human-evolution.jpg
What does this tell us about how humans have viewed their place in the story
of life on Earth?
2
What does it mean to be ‘advanced’ or ‘complex’? Use some examples
of living things to exemplify your ideas.
Human evolution and enhancement
Are you my cousin?
The evolutionary relationships between humans and non-human animals
have been extensively studied. This research has revealed, much to the
surprise of many, that all living things are very closely related and share
significant amounts of DNA; this is particularly true of genes that code for
things such as building limbs or skin. Our closest living relatives are the
chimpanzee and bonobo, with which we share over 98% of the same genetic
material. So what does this mean? Are we 98% chimpanzee, or are they 98%
human? The really interesting answer is that, although living things share
enormous amounts of DNA, what really matters is how the DNA is regulated,
especially considering that regulatory changes themselves are caused by
differences in the DNA.
Mitochondrial Eve
Within most cells are structures called mitochondria (the site of some stages
of respiration). Mitochondria contain their own little circle of DNA (mtDNA)
which is completely separate from the main DNA found inside the cell
nucleus. Whereas chromosomal DNA is inherited equally from both parents,
the mtDNA comes exclusively from the mother through the egg. Variations in
mtDNA can be used to follow the female line in human evolution. It appears
that all humans alive today can trace their mtDNA to a single female ancestor
(‘Mitochondrial Eve’) who is thought to have lived in East Africa around
200,000 years ago. This is around 150,000 years before humans are thought
to have migrated from Africa into Eurasia. The discovery of this unbroken
lineage in human evolution supports the idea that Homo sapiens only evolved
once and then spread out across the world; this is in contrast to the idea of
multiregional evolution, which argues that H. sapiens evolved separately on a
number of occasions throughout Africa and Eurasia.
Human enhancement
As technologies have developed, so have the opportunities to enhance
human characteristics, from drug doping in sport to plastic surgery. With the
development of genetic engineering, the scope for enhancement through
changes in genes is a real possibility. The first successful attempts at gene
therapy (providing working copies of genes to patients with genetic diseases)
were carried out in the early 1990s.
Worrying, albeit highly improbable, possibilities have been raised, such as
changing the characteristics of people (through engineering the embryo) to
make them faster runners or more intelligent. There are two major concerns
that some people have with enhancement:
1 It is costly and so, inevitably, wealthy parents would be able to pay for
their embryos to be enhanced, while the less wealthy would not. This
could result in a two-tier society of what the molecular biologist Lee Silver
calls ‘the naturals’ and the ‘GenRich’. So completely unlike the society we
have now then?
2 Use of embryos in research is ethically problematic because of
concerns about the value placed on human life or, from a religious
perspective, the sanctity of human life.
Activity G4.2
A brave new world?
In small groups, discuss the following questions:
1
What might be the consequences of genetic enhancement in terms of
how society values different types of people?
2
Make a list of the ethical positions people might adopt concerning
genetic enhancement of embryos. (For example, suppose it were possible to
treat mild short-sightedness genetically and ensure ‘perfect’ eyesight.) Try to
rank these positions from ‘most important’ to ‘least important’. It might help if
you think about the ranking in terms of a specific individual (e.g. parent,
doctor, researcher).
3
Open your group discussion into a whole class discussion. Can a
consensus be agreed? If not, why not?
Further work
The issues raised in this lesson could be explored further in a project.
Possible project topics could be:
1
What rights does a human embryo have? How do these rights relate to
genetic enhancement?
2
Is genetic enhancement necessarily a good thing? What problems might
be associated with it?
G4.2
Food by design
Early agriculture
Agriculture is the human activity of producing and processing crops or animals
for human use. The history of agriculture is long and complex, with
archaeological evidence to suggest that it was developed independently in the
Middle East, China and the Americas as the last ice sheet retreated, around
10,000 years ago. Before this time, humans probably lived in small nomadic
groups often described as hunter-gatherers. As the climate warmed and
became drier, there were greater opportunities to use the land for food
production and it is around this period that the first agricultural tools, such as
sickles, are found. In the Middle East the first crops to be domesticated (bred
for human use) were grasses such as wheat and barley; in China it was rice
and beans such as mung and soy. Plants selected and used by humans in
this way are called cultigens. Earlier than this, maybe as long ago as 30,000
years, humans had domesticated the wolf and were using it to help hunt
larger animals, such as bison. Certainly, by around 9,000 years ago there is
evidence to show that sheep and goat domestication had taken place and
that these animals were providing milk, skins and meat for humans.
Activity G4.3
Early agriculture
In small groups, discuss the following questions.
1
Using Darwin’s theories, explain how early humans could have
domesticated the wolf.
2
What features do you think early humans would have looked for in the
plants they domesticated?
Selective breeding of plants and animals
It was not until the mid-nineteenth century that people deliberately started to
cross closely (or sometimes distantly) related plant species, a process called
interbreeding, to produce plants with specific characteristics (cultivars). This
normally involved manual transfer of pollen from one species to another and
then a lengthy process of breeding from the new forms of hybrid to ensure
that the desired characteristics were present.
The manipulation of animals by humans (for example controlling which
animals are allowed to mate, neutering animals to prevent mating and make
them more docile, and culling animals with undesirable traits) has led to the
formation of pure breeding animals called pedigrees. In the world of farming
and animal showing, the keeping of detailed records of each animal is
essential to maintain pure breeding stock and to help prevent inbreeding
(breeding between closely related individuals).
Activity G4.4
Selective breeding of plants and animals
The production of pure breeding plants and animals often results in the loss of
genetic variation. In small groups, discuss the following questions.
1
What problems might result from this loss of variation?
2
How might these problems affect our ability to feed the planet given the
increasing demand for food as the human population increases?
Modern methods of food production
Before the development of modern biotechnological techniques, individual
plants and animals used in the production of cultivars or pedigrees were
selected based on the visible characteristics (the phenotype), for example,
resistance to certain diseases or quantity of milk produced. The science of
genomics now means that specific biomarkers of plants and animals can be
sequenced reasonably quickly. For example, there are specific gene markers
that give a very good indication of the litter size pigs will produce or provide
protection from certain agrochemicals in wheat plants. With this information,
scientists are able to select specific individuals for the production of breeding
lines which can then be produced using traditional breeding techniques of
from cloning and cuttings in plants and artificial insemination or cloning in
animals.
Recent developments in biotechnology have also meant that specific genes
from one species can be inserted into the genome of another, possibly
distantly related, species; this is one form of genetic engineering. This means
that new breeding lines can be developed more quickly and with greater
certainty that the desired characteristics will be observed in the offspring.
The demand for food
As the world’s population increases, there is increasing demand on limited
resources. Modern methods of food production, such as the use of GM crops
have been seen by some people as a way to address this problem. Others
worry that the issues surrounding these farming practices cause more
problems than they solve. The development of a monoculture (a crop of
almost identical plants) has far-reaching implications regarding biodiversity
and loss of genetic information, and the production of ‘super’ animals raises
questions about the role and responsibilities that humans have regarding
animal health and welfare.
Patenting genetic information
Knowing how different genes or groups of genes give certain characteristics is
extremely valuable, both in terms of knowledge but also in the monetary
sense. The companies that discover the function of particular genes, or use
this knowledge to produce new breeding lines of plants and animals, are able
to patent their discoveries (a patent is a set of legal rights to have sole use of
the knowledge for a set period of time). For example, as of 2007, the top
three seed-producing corporations controlled almost 50% of patented seeds
and their seeds occupied almost 90% of the total area devoted to genetically
engineered seeds. This, coupled with the non-sharing of genetic knowledge
and the reliance that poorer farmers have on seed companies, has led to
major criticisms of biotechnology companies. The flip side of all of this is that
patents incentivise investment, which brings private money in, and this in turn
can vastly increase the rate of discovery.
An excellent example of how beneficial genetic engineering can be is
provided by the development of Golden Rice, a strain of rice that has been
modified to contain a molecule that helps people make vitamin A. Many
people in Africa and South East Asia rely on rice as their staple food crop but
suffer from vitamin A deficiency; Golden Rice could provide a cheap
alternative to vitamin supplements. The developer of this technology, Ingo
Potrykus, insisted that there were no patenting rights on the genes involved
and this has led to an open market on licenses called Humanitarian Free
Licenses, though this has been controversial.
Activity G4.5
Human responsibility for ‘nature’
In small groups, discuss the following questions.
1
Biotechnology companies have the right to patent genes and products of
genetic engineering
Make a list of the points for and against this right. Reflect on what you think
on a personal level and from the utilitarian perspective.
2
Knowing the exact pedigree of dogs is an important issue for the Kennel
Club. Pedigree show dogs are deliberately bred to have characteristics
viewed as desirable in particular breeds, but alongside these characteristics
there are inherited diseases and conditions that are also favoured by selective
breeding. List and discuss the ethical questions surrounding this topic and
discuss them using one or more ethical frameworks.
Further work
Questions about genetics and agriculture can be a fruitful source of ideas for
project work. For example, you could explore one of the following questions:
1
Are GM foods the solution to a world food shortage, or a means of
making more money for companies (and people) who are already wealthy?
2
Should selective breeding of pedigree animals for show purposes be
more closely regulated? (You could make this question more specific by
focusing on one particular type of animal, e.g. bulldogs, and researching the
particular characteristics that are selected – and any problems associated
with them. You could also find out about any current laws relating to the
breeding of show animals, and any rules set by relevant organisations such
as the Kennel Club.)
Section G5 Genetics in the laboratory
G5.1
Laboratory-based projects
Getting practical with genetics in school
Although the science of genetics and, in particular, genetic engineering and
genomic studies often sound like the stuff of science fiction, there are plenty
of opportunities to carry out investigative work in schools and colleges. An
option for the EPQ is to carry out and report on investigative work or the
making of an artefact, and there are several areas of genomic study which
lend themselves to this.
Below are some examples of the type of work you could carry out that would
draw together some of the ideas you have been looking at in this sequence of
lessons. All of the examples involve plants and, in particular, those in the
genus Brassica.
Brassicas
The brassicas form a large group of plants that includes the crop plants
cabbages, cauliflower, turnips, mustard and oilseed rape, as well as some
horticultural plants and some weeds. Because of their economic importance,
the brassicas have been intensively studied, both in terms of increasing crop
yield but also because of their interesting ancestry.
Three of the most important crops in this group, cabbage, mustard and
oilseed rape, have been shown to share a common ancestry and were formed
through a complex hybridisation (joining together of two species) which has
resulted in them containing four genomes derived from their ancestors i.e.
they are allotetraploids. This, together their rapid growth, makes brassicas
ideal for practical work in the field of genetics.
Investigation
Here are some examples of possible Investigation EPQs using brassicas.
The effect of inbreeding on the phenotype (observable characteristics that are
under genetic control)
This could involve growing ‘wild-type’ plants (those that show the ancestral
characteristics) and cultivars and investigating the effect of only allowing
breeding within two small populations.
Growth rates in different species of Brassica
Measuring growth can be done in a variety of ways (height, dry mass, wet
mass, leaf size and number). Different cultivars and species could be
compared and linked to their use as crops in different parts of the world.
Effect of environmental conditions on different species of Brassica
Brassicas grow well in normal potting compost but do require good lighting
conditions. An investigation in how factors such as temperature, light
intensity, duration of light or nutrient availability could yield some interesting
results about ecophenotypic plasticity (how phenotypes respond to
changes in their environment).
Self-incompatibility in Brassica species
Most species of brassica are self-incompatible (i.e. they cannot selfpollinate) but some mutant strains are self-compatible (are able to selfpollinate). It could be interesting to link these characteristics to the evolution
and development of these mutant strains.
Artefact
An Artefact could involve the production of a new cultivar or hybrid. Breeding
experiments between different species of brassica could be used to develop
new strains with specific characteristics.
For this type of project, you would need to develop a design brief for the
cultivar or hybrid, and report on the development process.