Biology Revision U5
Michaelmas 1:
Communicable diseases:
Diseases caused by viruses, bacteria, protists and fungi are spread in animals and
plants.
The spread of diseases can be reduced or prevented.
Pathogens are microorganisms that cause infectious disease. Pathogens may be
viruses, bacteria, protists or fungi. They may infect plants or animals and can be
spread by direct contact, by water or by air.
Bacteria and viruses may reproduce rapidly inside the body.
Bacteria may produce poisons (toxins) that damage tissues and make us feel ill.
Viral diseases:
Measles:
- Virus
- Transmitted by coughing and sneezing and releasing small droplets of measles
- Effect is sweating, feeling ill and spots on the body
- No treatment
- Prevention through vaccination
HIV:
- Virus
- Transmitted through sex or drug users sharing a needle (blood)
- No treatment
- Prevention by using condoms
Tobacco mosaic virus:
- Virus
- Transmitted by contact between diseased plants
- Effect is a ‘mosaic’ pattern on leaves as it destroys the cells
- No treatment
- Prevented by TMV resistant strains
Bacterial diseases:
Salmonella:
- Bacteria
- Transmitted through raw eggs and chicken
- Effect is throwing up and cramps
- No treatment
- Prevention not getting raw chicken in contact with other food
Gonorrhoea:
- Bacteria
- Transmitted through sex
- Effect is a yellow discharge and pain whilst urinating
- Treatment through antibiotics
, - Prevention through condoms
Fungal diseases:
Rose black spot:
- Fungi
- Transmitted through wind and rain
- Effect is black/purple spots on leaves
- Treatment is too remove affected leaves or chemicals
- No prevention
Protist diseases:
Malaria:
- Protist
- Transmitted through mosquitoes
- Effect is episodes of fever (constantly hot or cold)
- Prevention is antimalarial drugs, preventing mosquitoes from breeding and using
mosquito nets
Human defence systems:
Non-specific defence:
- Skin
- Nose
- Trachea
- Stomach
Immune system:
- This is the body’s second line of defence (the white blood cells in your immune
system)
- 1) Ingesting microorganisms – some white blood cells take in the pathogen,
digesting it and destroying it.
- 2) Producing antibodies – some white blood cells produce antibodies that target
particular pathogens, destroying them. You need a unique type of antibody for
every pathogen. Once your blood cells have produced this antibody once against
a particular pathogen, they can be made very quickly if the pathogen enters your
body again.
- 3) Producing antitoxins – some white blood cells produce anti toxins. These
counter act the toxins released by pathogens.
Vaccinations:
Vaccinations prevent people from getting ill
This involves giving you an injection containing a dead or inactive form of a disease-
causing microorganism. It stimulates your body’s natural immune response to
invading pathogens.
These inactive pathogens stimulate the white blood cells to produce antibodies
needed to fight the pathogen and prevent you from getting ill.
, Then, if you meet the same pathogen, your white blood cells will have a rapid
response.
Antibiotics and painkillers:
Antibiotics:
- Antibiotics are used to help cure bacterial diseases by killing infective bacteria
inside the body.
- You can use antiseptics or disinfectants to kill bacteria outside the body
Painkillers:
- Painkillers are used to treat the symptoms of diseases, but do not kill pathogens
- Such as aspirin and paracetamol
Discovering drugs:
Traditionally, drugs were extracted from plants or microorganisms:
- The heart drug digitalis originates from foxgloves
- The painkiller aspirin originates from willow
- Penicillin was discovered by Alexander Fleming from Penicillium mould
Alexander Fleming’s discovery:
- He was growing bacteria for study purposes
- After a holiday, he saw that lots of his culture plates had mould growing around
it and a clear ring of jelly around the mould.
- He then realised that something had killed the bacteria
- He called the substance that killed the bacteria, penicillin
Developing drugs:
New medical drugs have to be tested and trialled before being used to check that
they are safe and effective.
Preclinical testing is done in laboratories using cells, tissues and live animals. This is
done to see if they are toxic and do their job.
Clinical trials use healthy volunteers and patients
Firstly, very low doses are given to the volunteers see any side effects
If the drug seems safe, it is tried on a small number of patients to see if it treats the
disease.
If it seems to be effective, bigger clinical trials take place.
There are also double blind trials where a group of patients get the drug and a group
get a placebo.
This is to make sure the test isn’t biased
Michaelmas 2:
Monoclonal antibodies:
How are monoclonal antibodies made?
- These are proteins that are produced to target particular cells or chemicals in the
body.
Michaelmas 1:
Communicable diseases:
Diseases caused by viruses, bacteria, protists and fungi are spread in animals and
plants.
The spread of diseases can be reduced or prevented.
Pathogens are microorganisms that cause infectious disease. Pathogens may be
viruses, bacteria, protists or fungi. They may infect plants or animals and can be
spread by direct contact, by water or by air.
Bacteria and viruses may reproduce rapidly inside the body.
Bacteria may produce poisons (toxins) that damage tissues and make us feel ill.
Viral diseases:
Measles:
- Virus
- Transmitted by coughing and sneezing and releasing small droplets of measles
- Effect is sweating, feeling ill and spots on the body
- No treatment
- Prevention through vaccination
HIV:
- Virus
- Transmitted through sex or drug users sharing a needle (blood)
- No treatment
- Prevention by using condoms
Tobacco mosaic virus:
- Virus
- Transmitted by contact between diseased plants
- Effect is a ‘mosaic’ pattern on leaves as it destroys the cells
- No treatment
- Prevented by TMV resistant strains
Bacterial diseases:
Salmonella:
- Bacteria
- Transmitted through raw eggs and chicken
- Effect is throwing up and cramps
- No treatment
- Prevention not getting raw chicken in contact with other food
Gonorrhoea:
- Bacteria
- Transmitted through sex
- Effect is a yellow discharge and pain whilst urinating
- Treatment through antibiotics
, - Prevention through condoms
Fungal diseases:
Rose black spot:
- Fungi
- Transmitted through wind and rain
- Effect is black/purple spots on leaves
- Treatment is too remove affected leaves or chemicals
- No prevention
Protist diseases:
Malaria:
- Protist
- Transmitted through mosquitoes
- Effect is episodes of fever (constantly hot or cold)
- Prevention is antimalarial drugs, preventing mosquitoes from breeding and using
mosquito nets
Human defence systems:
Non-specific defence:
- Skin
- Nose
- Trachea
- Stomach
Immune system:
- This is the body’s second line of defence (the white blood cells in your immune
system)
- 1) Ingesting microorganisms – some white blood cells take in the pathogen,
digesting it and destroying it.
- 2) Producing antibodies – some white blood cells produce antibodies that target
particular pathogens, destroying them. You need a unique type of antibody for
every pathogen. Once your blood cells have produced this antibody once against
a particular pathogen, they can be made very quickly if the pathogen enters your
body again.
- 3) Producing antitoxins – some white blood cells produce anti toxins. These
counter act the toxins released by pathogens.
Vaccinations:
Vaccinations prevent people from getting ill
This involves giving you an injection containing a dead or inactive form of a disease-
causing microorganism. It stimulates your body’s natural immune response to
invading pathogens.
These inactive pathogens stimulate the white blood cells to produce antibodies
needed to fight the pathogen and prevent you from getting ill.
, Then, if you meet the same pathogen, your white blood cells will have a rapid
response.
Antibiotics and painkillers:
Antibiotics:
- Antibiotics are used to help cure bacterial diseases by killing infective bacteria
inside the body.
- You can use antiseptics or disinfectants to kill bacteria outside the body
Painkillers:
- Painkillers are used to treat the symptoms of diseases, but do not kill pathogens
- Such as aspirin and paracetamol
Discovering drugs:
Traditionally, drugs were extracted from plants or microorganisms:
- The heart drug digitalis originates from foxgloves
- The painkiller aspirin originates from willow
- Penicillin was discovered by Alexander Fleming from Penicillium mould
Alexander Fleming’s discovery:
- He was growing bacteria for study purposes
- After a holiday, he saw that lots of his culture plates had mould growing around
it and a clear ring of jelly around the mould.
- He then realised that something had killed the bacteria
- He called the substance that killed the bacteria, penicillin
Developing drugs:
New medical drugs have to be tested and trialled before being used to check that
they are safe and effective.
Preclinical testing is done in laboratories using cells, tissues and live animals. This is
done to see if they are toxic and do their job.
Clinical trials use healthy volunteers and patients
Firstly, very low doses are given to the volunteers see any side effects
If the drug seems safe, it is tried on a small number of patients to see if it treats the
disease.
If it seems to be effective, bigger clinical trials take place.
There are also double blind trials where a group of patients get the drug and a group
get a placebo.
This is to make sure the test isn’t biased
Michaelmas 2:
Monoclonal antibodies:
How are monoclonal antibodies made?
- These are proteins that are produced to target particular cells or chemicals in the
body.
