Disease and the immune system

Question 1

What is the disease?

Answer 1

Disease is a condition that impairs the normal functioning of an organism. Both plants and animals can get diseases.

Question 2

What is a pathogen?

Answer 2

A pathogen is an organism that causes disease. Types of pathogen include bacteria, viruses, fungi
and protoctista (a type of single-celled eukaryotic organism).

Question 3

What is a communicable disease?

Answer 3

A communicable disease is a disease that can spread between organisms.

Question 4

what are the four pathogens?

Answer 4

bacterium
virus
fungus
protocist

Question 5

what are three examples of bacterium?

Answer 5

tuberculosis
bacterial meningitis
Ring rot

Question 6

What is tuberculosis?

who does it affect?

Answer 6

Animals, typically humans and cattle
TB is spread directly via droplet infection (see previous page). It’s also spread indirectly
because the bacteria can remain in the air for long periods of time and infect new people.
The risk of TB infection is increased when lots of people live crowded together in a small space.

Question 7

What is bacterial meningitis?

Who does it affect?

Answer 7

Humans

Question 8

What does ring rot affect?

Answer 8

potatoes and tomatoes

Question 9

what are three examples of viruses?

Answer 9

HIV / AIDS
influenza
tobacco mosaic virus

Question 10

what does HIV/AIDS affect?

Answer 10

humans

Question 11

what does influenza affect?

Answer 11

animals including humans

Question 12

Who does TMV affect?

Answer 12

Plants

Question 13

What are three examples of fungi?

Answer 13

black sigatoka
ringworm
athletes foot

Question 14

what does black sigatoka affect?

Answer 14

banana plants

Question 15

what does ringworm effect?

Answer 15

Cattle

Question 16

what does athlete’s foot affect?

Answer 16

humans

Question 17

what are two examples of a protocist?

Answer 17

potato/tomato late blight

malaria

Question 18

what does potato/ tomato late blight affect

Answer 18

potato and tomato

Question 19

what does malaria affect?

Answer 19

Animals including humans

Question 20

what two ways can communicable diseases be transmitted?

Answer 20

direct transmission on indirect transmission

Question 21

what is direct transmission?

Answer 21

1) Direct transmission is when a disease is transmitted directly from one organism to another. Direct transmission can happen in several ways, including: droplet infection (coughing or sneezing tiny
droplets of mucus or saliva directly onto someone), sexual intercourse, or touching an infected organism.

Examples:
• HIV can be transmitted directly between humans via sexual intercourse.
• Athlete’s foot can be spread via touch.

Question 22

what is indirect transmission?

Answer 22

2) Indirect transmission is when a disease is transmitted from one organism to another via an intermediate.
Intermediates include air, water, food or another organism (known as a vector).

Examples:
• Potato/tomato late blight is spread when spores are carried
between plants — first in the air, then in water.
• Malaria is spread between humans (and other animals) via mosquitoes — insects that feed on blood. The mosquitoes act as vectors — they don’t cause malaria themselves, they just spread the protoctista that cause it.

Question 23

what living conditions can affect disease transmission?

Answer 23

overcrowded living conditions
Climate
social factors

Question 24

How does overcrowded living conditions affect transmittion?

Answer 24

1) Overcrowded living conditions increase the transmission of many communicable diseases.

Example:
TB is spread directly via droplet infection (see previous page). It’s also spread indirectly because the bacteria can remain in the air for long periods of time and infect new people. The risk of TB infection is increased when lots of people live crowded together in a small space.

Question 25

How does climate affect disease transmission?

Answer 25

2) Climate can also affect the spread of communicable diseases.

Examples:
• Potato/tomato late blight is especially common during wet summers because the
spores need water to spread (see previous page).
• Malaria is most common in tropical countries, which are humid and hot. This is because these are the ideal conditions for mosquitoes (the malaria vectors) to breed.

Question 26

how does social factors affect disease transmission?

Answer 26

3) In humans, social factors can increase the transmission of communicable diseases.
Example:
The risk of HIV infection is high in places where there’s limited access to: • good healthcare — people are less likely to be diagnosed and treated for HIV, and the most effective anti-HIV drugs are less likely to be available, so the virus is more likely to be passed on to others.
• good health education — to inform people about how HIV is transmitted and how it can be avoided, e.g. through safe-sex practices like using condoms.

Question 27

what do pathogens need to do to cause a disease?

Answer 27

enter an organism

Question 28

what are six barriers that animals have to prevent infection?

Answer 28

skin mucous
membranes  
blood clotting  
inflammation 
wound repair
expulsive reflexes

Question 29

how does skin prevent infection?

Answer 29

Skin — this acts as a physical barrier, blocking pathogens from entering
the body. It also acts as a chemical barrier by producing chemicals that
are antimicrobial and can lower pH, inhibiting the growth of pathogens.

Question 30

how does mucus membranes prevent infection?

Answer 30

Mucous membranes — these protect body openings that are exposed to the environment
(such as the mouth, nostrils, ears, genitals and anus). Some membranes secrete mucus —
a sticky substance that traps pathogens and contains antimicrobial enzymes.

Question 31

how does blood clotting prevent infection?

Answer 31

Blood clotting — a blood clot is a mesh of protein (fibrin) fibres. Blood clots plug wounds to
prevent pathogen entry and blood loss. They’re formed by a series of chemical reactions that
take place when platelets (fragments of cells in the blood) are exposed to damaged blood vessels.

Question 32

how does inflammation prevent infection?

Answer 32

Inflammation — the signs of inflammation include swelling, pain, heat and
redness. It can be triggered by tissue damage — the damaged tissue releases
molecules, which increase the permeability of the blood vessels, so they
start to leak fluid into the surrounding area. This causes swelling and helps
to isolate any pathogens that may have entered the damaged tissue.
The molecules also cause vasodilation (widening of the blood vessels), which
increases blood flow to the affected area. This makes the area hot and brings
white blood cells to the area to fight off any pathogens that may be present.

Question 33

how does wound repair prevent an infection?

Answer 33

Wound repair — the skin is able to repair itself in the event of injury
and re-form a barrier against pathogen entry. The surface is repaired
by the outer layer of skin cells dividing and migrating to the edges
of the wound. The tissue below the wound then contracts to bring
the edges of the wound closer together. It is repaired using collagen
fibres — too many collagen fibres and you’ll end up with a scar.

Question 34

How does Expulsive reflexes prevent infection?

Answer 34

Expulsive reflexes — e.g. coughing and sneezing. A sneeze happens
when the mucous membranes in the nostrils are irritated by things such
as dust or dirt. A cough stems from irritation in the respiratory tract.
Both coughing and sneezing are an attempt to expel foreign objects,
including pathogens, from the body. They happen automatically.

Question 35

how do plants prevent disease?

Answer 35

Physical and chemical defences

Question 36

what are a plants physical defenses against pathogens?

Answer 36

1) Most plant leaves and stems have a waxy cuticle, which provides a physical barrier against pathogen entry. It may also stop water collecting on the leaf, which could reduce the risk of infection by pathogens that are transferred between plants in water. 2) Plant cells themselves are surrounded by cell walls. These form a physical barrier against pathogens that make it past the waxy cuticle. 3) Plants produce a polysaccharide called callose. Callose gets deposited between plant cell walls and plasma membranes during times of stress, e.g. pathogen invasion. Callose deposition may make it harder for pathogens to enter cells. Callose deposition at the plasmodesmata (small channels in the cell walls) may limit the spread of viruses between cells.

Question 37

What are plants chemical defenses against pathogens?

Answer 37

1) Plants don’t just rely on physical defences. They also produce antimicrobial chemicals (including antibiotics) which kill pathogens or inhibit their growth.
Examples:
• Some plants produce chemicals called saponins. These are thought
to destroy the cell membranes of fungi and other pathogens.
• Plants also produce chemicals called phytoalexins,
which inhibit the growth of fungi and other pathogens.
2) Other chemicals secreted by plants are toxic to insects — this reduces the amount of insect-feeding
on plants and therefore reduces the risk of infection by plant viruses carried by insect vectors.

Question 38

What is an antigen?

Answer 38

1) Antigens are molecules (usually proteins or polysaccharides) found on the surface of cells.

Question 39

how do foreign antigens trigger an immune response?

Answer 39

1) Antigens are molecules (usually proteins or polysaccharides) found on the surface of cells. 2) When a pathogen (like a bacterium) invades the body, the antigens on its cell surface are identified as foreign, which activates cells in the immune system. 3) The immune response involves specific and non-specific stages. The non-specific response happens in the same way for all microorganisms — whatever foreign antigens they have. The specific response is antigen-specific —
it is aimed at specific pathogens. It involves white blood cells called T and B lymphocytes.

Question 40

what are the four main stages in the immune response?

Answer 40

phagocytes engulf pathogens
phagocytes activate T lymphocytes
T lymphocytes activate B lymphocytes which divides into plasma cells
plasma cells make more antibodies to a specific antigen

Question 41

what is a phagocyte?

Answer 41

A phagocyte is a type of white blood cell that carries out phagocytosis (engulfment of pathogens). They’re found in the blood and in tissues and carry out a non-specific immune response. Here’s how they work:

Question 42

what happens when phagocytes engulf pathogens?

Answer 42

1) A phagocyte recognises the antigens on a pathogen. 2) The cytoplasm of the phagocyte moves round the pathogen, engulfing it. This may be made easier by the presence of opsonins— molecules in the blood that attach to foreign antigens to aid phagocytosis. 3) The pathogen is now contained in a phagosome (a type of vesicle) in the cytoplasm of the phagocyte. 4) A lysosome (an organelle that contains digestive enzymes) fuses with the phagosome. The enzymes
break down the pathogen. The phagocyte then presents the pathogen’s antigens. It sticks the antigens on its surface to activate other immune system cells. When a phagocyte does this it is acting as an antigen-presenting cell (APC).

Question 43

How Opsonins do work?

Answer 43

Opsonins work in different
ways. Some hide the
negative charges on the
membrane of the pathogen,
making it easier for the
negatively-charged phagocyte
to get closer to the pathogen.

Question 44

what are neutrophils?

Answer 44

Neutrophils are a type of phagocyte. They’re the first white blood cells to respond to a pathogen inside the body. Neutrophils move towards a wound in response to signals from cytokines (proteins that act as messenger molecules). The cytokines are released by cells at the site of the wound.

Question 45

what is a t lymphocytes?

Answer 45

1) A T lymphocyte is another type of white blood cell.

Question 46

what happens when phagocytes activate T lymphocytes?

Answer 46

1) A T lymphocyte is another type of white blood cell.2) Their surface is covered with receptors. 3) The receptors bind to antigens presented by APCs. 4) Each T lymphocyte has a different receptor on its surface. 5) When the receptor on the surface of a T lymphocyte meets a complementary antigen, it binds to it — so each T lymphocyte will bind to a different antigen. 6) This activates the T lymphocyte — the process is called clonal selection. 7) The T lymphocyte then undergoes clonal expansion — it divides to produce clones of itself. Different types of T lymphocytes carry out different functions — see next page.

Question 47

What are the three types of lymphocytes?

Answer 47

1) T helper cells
2) T killer cells
3) T regulatory cells

Question 48

what are T helper cells?

Answer 48

1) T helper cells — these release substances to activate B lymphocytes and T killer cells.

Question 49

what are T killer cells?

Answer 49

2) T killer cells — these attach to and kill cells that are infected with a virus.

Question 50

what are T regulatory cells?

Answer 50

3) T regulatory cells — these suppress the immune response from other white blood cells.
This helps to stop immune system cells from mistakenly attacking the host’s body cells.

Question 51

What happens when the T lymphocytes activate the B lymphocyte which divides into plasma cells?

Answer 51

1) B lymphocytes are another type of white blood cell. 2) They’re covered with proteins called antibodies. 3) Antibodies bind to antigens to form an antigen-antibody complex. 4) Each B lymphocyte has a different shaped antibody on its surface. 5) When the antibody on the surface of a B lymphocyte meets a complementary shaped antigen, it binds to it — so each B lymphocyte will bind to a different antigen. 6) This, together with substances released from T helper cells, activates the B lymphocyte. This process is another example of clonal selection. 7) The activated B lymphocyte divides, by mitosis, into plasma cells and
memory cells. This is another example of clonal expansion

Question 52

what happens within cell signaling?

Answer 52

1) Cell signalling is basically how cells communicate. 2) A cell may release (or present) a substance that binds to the receptors on another cell — this causes a response of some kind in the other cell.
3) Cell signalling is really important in the immune response because it helps to activate all the different types of white blood cells that are needed. 4) For example, T helper cells release interleukins (a type of cytokine) that bind to receptors on B lymphocytes. This activates the B lymphocytes — the T helper cells are signalling to the B lymphocytes that there’s a pathogen in the body.

Question 53

what happens when plasma cells make more antibodies to a specific antigen?

Answer 53

1) Plasma cells are clones of the B lymphocyte (they’re identical to the B lymphocyte).
2) They secrete loads of the antibody, specific to the antigen, into the blood. 3) These antibodies will bind to the antigens on the surface of the pathogen to form lots of antigen-antibody complexes.

Question 54

what is structure of an antigen?

Answer 54

DRAWING ON OTHER FLASHCARD!!!!
• Antibodies are glycoproteins made of four polypeptide chains —
two heavy chains and two light chains. Each chain has a variable region and a constant region.
• The variable regions of the antibody form the antigen binding sites.
The shape of the variable region is complementary to a particular antigen. The variable regions differ between antibodies.
• The hinge region allows flexibility when the antibody binds to the antigen.
• The constant regions allow binding to receptors on immune system cells, e.g. phagocytes. The constant region is the same (i.e. it has the same sequence of amino acids) in all antibodies.
• Disulfide bridges (a type of bond) hold the polypeptide chains of the protein together.

Question 55

What 3 ways do antibodies help clear infection?

Answer 55

1) Agglutinating pathogens
2) Neutralising toxins
3) Preventing the pathogen binding to human cells

Question 56

What is agglutinating pathogens?

Answer 56

1) Agglutinating pathogens — each antibody has two binding sites, so an antibody can bind to two pathogens at the same time — the
pathogens become clumpedtogether. Phagocytes then bind to the antibodies and phagocytose a lot of pathogens all at once. Antibodies that behave in this way are known as agglutinins.

Question 57

What is neutralising toxins?

Answer 57

2) Neutralising toxins — like antigens, toxins have different shapes.
Antibodies called anti-toxins can bind to the toxins produced by pathogens. This prevents the toxins from affecting human cells, so the toxins are neutralised (inactivated). The toxin-antibody complexes are also phagocytosed.

Question 58

What is Preventing the pathogen binding to human cells?

Answer 58

3) Preventing the pathogen binding to human cells — when antibodies bind to the antigens on pathogens, they may block the cell surface receptors that the pathogens need to bind to the host cells. This means the pathogen can’t attach to or infect the host cells.

Question 59

Why is the primary response slow?

Answer 59

1) When a pathogen enters the body for the first time, the antigens on its surface activate the immune system. This is called the primary response. 2) The primary response is slow because there aren’t many B lymphocytes that can make the antibody needed to bind to it.
3) Eventually the body will produce enough of the right antibody to overcome the infection. Meanwhile the infected person will show symptoms of the disease. 4) After being exposed to an antigen, both T and B lymphocytes produce memory cells. These memory cells remain in the body for a long time. 5) Memory T lymphocytes remember the specific antigen and will recognise it a second time round. Memory B lymphocytes record the specific antibodies
needed to bind to the antigen.
6) The person is now immune — their immune system has the ability to respond
quickly to a second infection.

Question 60

Why is the secondary response faster?

Answer 60

1) If the same pathogen enters the body again,
the immune system will produce a quicker, stronger
immune response — the secondary response. 2) Clonal selection
happens faster. Memory B lymphocytes are activated and divide into plasma cells that produce the right antibody to the antigen. Memory T lymphocytes are activated and divide into the correct type of. T lymphocytes to kill the cell carrying the antigen. 3) The secondary response often gets rid of the pathogen before you begin to show any symptoms.

Question 61

Similarities and differences between primary and secondary response?

Answer 61

Primary Secondary
Pathogen 1st time 2nd
speed of response slow fast
cells activated B + T lymphocytes Memory cells
symptoms yes no

Question 62

How to examine blood smears?

Answer 62

1) As the name suggests, a blood smear is a sample of blood smeared over a microscope slide. 2) Stains are added to the sample to make the different cells easy to see 3) When looking at a blood smear you’re likely to see red blood cells, white blood cells and
platelets (tiny fragments of cells involved in blood clotting). Some types of white blood cells have granules in their cytoplasm (so they look grainy) and other types don’t.

Question 63

What does blood smears look like?

Answer 63

red blood cells don’t have a nucleus.
neutrophil. Its nucleus looks like three interconnected
blobs the nucleus is ‘multi-lobed’. The cytoplasm of a neutrophil is grainy. lymphocyte. It’s much smaller than the neutrophil.
The nucleus takes up most of the cell and there’s very little
cytoplasm to be seen (it’s not grainy either). You can’t tell whether
this is a T lymphocyte or a B lymphocyte under a light microscope.
This is a monocyte. It’s the biggest white blood cell and a type of phagocyte.it has a kidney-bean shaped nucleus and a non-grainy cytoplasm.

Question 64

What can immunity be?

Answer 64

active or passive

Question 65

What is active immunity?

Answer 65

ACTIVE IMMUNITY
This is the type of immunity you get when your immune system makes its own antibodies after being stimulated by an antigen.

Question 66

How many types of active immunity are there?

Answer 66

There are two different types of active immunity

Question 67

What are the 2 types of active immunity?

Answer 67

Natural and artificial vaccination

Question 68

What is natural active immunity?

Answer 68

1) Natural — this is when you become immune after catching a disease. E.g. if you have measles as a child, you shouldn’t be able to catch it again in later life.

Question 69

What is artificial vaccination in active immunity?

Answer 69

2) Artificial — this is when you become immune after you’ve been given a vaccination containing a harmless dose of antigen

Question 70

What is passive immunity?

Answer 70

This is the type of immunity you get from being given antibodies made by a different organism — your immune system doesn’t produce any antibodies of its own.

Question 71

How many types of passive immunity is there?

Answer 71

Again, there are two types:

Question 72

What are the two types of passive immunity?

Answer 72

Natural

Artificial antibodies

Question 73

What is natural passive imunity?

Answer 73

1) Natural — this is when a baby becomes immune due to the antibodies it receives from its mother, through the placenta and in breast milk.

Question 74

What is Artificial antibodies in passive immunity?

Answer 74

2) Artificial — this is when you become immune after being injected with
antibodies from someone else. E.g. If you contract tetanus you can be injected with antibodies against the tetanus toxin, collected from blood donations.

Question 75

What are the similarities and differences between active and passive immunity?

Answer 75

Active immunity Passive immunity
Requires exposure to antigen No exposure to antigen
It takes a while for protection to develop Protection is immediate
Protection is long-term Protection is short-term
Memory cells are produced Memory cells aren’t
produced

Question 76

What do autoimmune diseases involve?

Answer 76

Abnormal immune response

Question 77

Why do autoimmune diseases involve an abnormal immune response?

Answer 77

1) Sometimes, an organism’s immune system isn’t able to recognise self-antigens — the antigens present on the organism’s own cells.
2) When this happens, the immune system treats the self-antigens as foreign antigens
and launches an immune response against the organism’s own tissues.
3) A disease resulting from this abnormal immune response is known as an autoimmune disease.
4) Autoimmune diseases are usually chronic (long-term). They can often be treated, but not cured.

Question 78

What are 2 examples of an autoimmune disease?

Answer 78

lupus

rheumatoid arthritis

Question 79

What is lupus?

Answer 79

• Lupus — caused by the immune system attacking cells in the connective tissues. This damages the tissues and causes painful inflammation (see page 100). Lupus can affect the skin and joints, as well as organs such as the heart and lungs.

Question 80

What is rheumatoid arthiritis?

Answer 80

• Rheumatoid arthritis — caused by the immune system attacking cells in the joints.
Again this causes pain and inflammation.

Question 81

How do vaccines help to control disease?

Answer 81

1) While your B lymphocytes are busy dividing to build up their numbers to deal with a pathogen (i.e. the primary response), you suffer from the disease. Vaccination can help avoid this. 2) Vaccines contain antigens that cause your body to produce memory cells against a particular pathogen, without the pathogen causing disease. This means you become immune without getting any symptoms.
3) If most people in a community are vaccinated, the disease becomes extremely rare. This means that even people who haven’t been vaccinated are unlikely to get the disease, because there’s no one to catch it from. This is called herd immunity. It helps to prevent epidemics — mass outbreaks of disease. 4) Vaccines always contain antigens — these may be free or attached to a dead or attenuated (weakened) pathogen. 5) Sometimes booster vaccines are given later on (e.g. after several years) to make sure memory cells are produced.
6) Vaccination is not the same as immunisation. Vaccination is the administration of antigens (in a vaccine) into the body. Immunisation is the process by which you develop immunity. Vaccination causes immunisation.

Question 82

What are 2 examples of routine vaccinations?

Answer 82

MMR

Meningitis C vaccine

Question 83

What is the MMR vaccine?

Answer 83

• the MMR — protects against measles, mumps and rubella. The MMR is usually given to children as an injection at around a year old, and again before they start school. It contains attenuated measles, mumps and rubella viruses.

Question 84

What is the Meningitis C vaccine?

Answer 84

the Meningitis C vaccine — protects against the bacteria that cause Meningitis C. It is first given as an injection to babies at 3 months. Boosters are then given to 1-year-olds and teenagers.

Question 85

Vaccine program- influenza?

Answer 85

The influenza (flu) vaccine changes every year. That’s because the antigens on the surface of the influenza virus change regularly, forming new strains of the virus. 2) Memory cells produced from vaccination with one strain of the flu will not recognise other strains with different antigens. The strains are immunologically distinct.
3) Every year there are different strains of the influenza virus circulating in the population, so a different vaccine has to be made.
4) Laboratories collect samples of these different strains, and organisations, such as the WHO (World Health Organisation) and CDC (Centre for Disease Control), test the effectiveness of different influenza vaccines against them. 5) New vaccines are developed and one is chosen every year that is the most effective against the recently circulating influenza viruses. virus 6) Governments and health authorities then implement a programme of vaccination using
the most suitable vaccine. Sometimes people are given a vaccine that protects them from a strain causing an epidemic in another country — this helps to stop the strain spreading globally.

Question 86

Why are antibiotics extremely useful?

Answer 86

1) Antibiotics are chemicals that kill or inhibit the growth of bacteria.
2) They’re used by humans as drugs to treat bacterial infections. They’re useful because they can usually target bacterial cells without damaging human body cells. 3) Penicillin was the first antibiotic to be isolated (by Alexander Fleming, in 1928).
4) Antibiotic use became widespread from the mid-twentieth century — partly thanks to the successful treatment of soldiers with penicillin in the Second World War. 5) For the past few decades, we’ve been able to deal with bacterial infections pretty easily using antibiotics.
As a result of this, the death rate from infectious bacterial disease has fallen dramatically. 6) Despite their usefulness, there are risks to using antibiotics. For example, they can cause side effects and even severe allergic reactions in some people. Perhaps the biggest risk though, is from antibiotic resistance…

Question 87

Why antibiotic resistance is a big problem?

Answer 87

1) There is genetic variation in a population of bacteria.
Genetic mutations make some bacteria naturally resistant to an antibiotic. 2) For the bacterium, this ability to resist an antibiotic is a big advantage. It’s better able to survive, even in a host who’s being treated with antibiotics to get rid of the infection, and so it lives for longer and reproduces many more times. 3) This leads to the allele for antibiotic resistance being passed on to lots of offspring. It’s an example of natural selection — see page 127. This is how antibiotic resistance spreads and becomes more common in a population of bacteria over time. 4) This is a problem for people who become infected with these bacteria, because you can’t easily get rid of them with antibiotics.
5) Increased use of antibiotics means that antibiotic resistance is increasing. Superbugs’ that are resistant to most known antibiotics are becoming more common. This means we are less able to treat some potentially life-threatening bacterial infections.

Question 88

What are 2 types of antibiotic resistant bacteria?

Answer 88

MRSA

Clostridium difficile

Question 89

What is MRSA?

Answer 89

• MRSA (meticillin-resistant Staphylococcus aureus) causes serious wound infections and is
resistant to several antibiotics, including meticillin (which used to be called methicillin).

Question 90

What is Clostridium difficile?

Answer 90

• Clostridium difficile infects the digestive system, usually causing problems in people who have already been treated with antibiotics. It is thought that the harmless bacteria that are normally present in the digestive system are killed by the antibiotics, which
C. difficile is resistant to. This allows C. difficile to flourish. C. difficile
produces a toxin, which causes severe diarrhoea, fever and cramps

Question 91

What are ways of reducing antibiotic resistance?

Answer 91

Developing new antibiotics and modifying existing ones are two ways of overcoming the current problem of antibiotic resistance. This isn’t easy though. To reduce the likelihood of antibiotic resistance developing in the first place, doctors are being encouraged to reduce
their use of antibiotics, e.g. not to prescribe them for minor infections and not to prescribe them to prevent infections
(except in patients with already weak immune systems, e.g. the elderly or people with HIV). Patients are advised to
take all of the antibiotics they’re prescribed to make sure the infection is fully cleared and all the bacteria have been
killed (which reduces the likelihood of a population of antibiotic-resistant bacteria developing).

Question 92

Why do sources of medicine need to be protected?

Answer 92

1) Many medicinal drugs are manufactured using natural compounds found in plants, animals or microorganisms. E.g. penicillin is obtained from a fungus, some cancer drugs are made using soil bacteria, and daffodils are now grown to produce a drug used to treat Alzheimer’s disease. 2) Only a small proportion of organisms have been investigated so far, so it’s possible that plants or microorganisms exist that contain compounds that could be used to treat currently incurable diseases, such as AIDS. Others may produce new antibiotics. 3) Possible sources of drugs need to be protected by maintaining the biodiversity (the variety of different species) on Earth. If we don’t protect them, some species could die out before we get
a chance to study them. 4) Even organisms that have already been studied could still prove to be useful sources of medicines as new techniques are developed for identifying, purifying and testing compounds.

Question 93

What are personalized medicines?

Answer 93

1) Your genes determine how your body responds to certain drugs. Different people respond to the same drug in different ways — which makes certain drugs more effective for some people than others.
This is where personalised medicines come in. 2) Personalised medicines are medicines that are tailored to an individual’s DNA. The theory is that if doctors have your genetic information, they can use it to predict how you will respond to different drugs and only prescribe the ones that will be most effective for you. 3) Scientists hope that by studying the relationship between someone’s genetic make-up and their responsiveness to drugs, can be produced in the future.

Question 94

What is synthetic bio?

Answer 94

1) Synthetic biology involves using technology to design and make
things like artificial proteins, cells and even microorganisms.
2) It has applications in lots of different areas, including medicine.
For example, scientists are looking at engineering bacteria to
destroy cancer cells, while leaving healthy body cells intact.