These are revision notes/a summary about the Infection and Response Topic. This is for GCSE AQA Biology(triple science) Higher tier. These were made using the specification and CGP revision guide.
Viruses
Communicable diseases Vector - an organism that carries disease
A disease that can travel from person to Epidemic - outbreak in a few countries
person/animal Pandemic - outbreak across the world
How your body defends against diseases:
- Skin acts as a barrier to pathogens Prokaryotic cell - lacks nucleus, 1 cell organism
- Skin produces antimicrobial substances that Eukaryotic cell - organisms cell
kill pathogens
- Hairs and mucus in nose trap particles that Pathogen - a bacteria, virus or microorganism that
could contain pathogens can cause disease
- Stomach produces acid to kill pathogens Antibiotics - medicine that destroys/ stops the
- Trachea and bronchi secrete mucus to trap growth of microorganisms
pathogens
Antigens - toxins on foreign particles that may
Defective immune systems - increases a person's trigger an immune response
chances of getting a communicable disease Antibodies - a molecule made by white blood cells in
An immune system attacks and destroys pathogens, response to antigens, bind to them
mainly white blood cells
→ their body is less likely to defend against
pathogens that cause disease
Vaccine Viruses
1) Small amounts of Dead antigens/pathogens - Small microbes that live in other organisms
injected into body from the specific virus - Have protein coat instead of cell membrane
2) Lymphocytes detect the antigen and then and a string of DNA instead of nucleus
starts divide to produce memory cells - Use other cells to reproduce(cell damage
3) These memory cells retain the ability to makes us feel ill)
produce specific antibodies to that pathogen How they reproduce: 2 ways
4) Antibodies attach to the pathogens to stop 1 invading the host cell:
them being able to move freely so they can be 1) They attach onto a cell
trapped and stopped 2) They give the cell their genetic information
5) Phagocytes ingest the antigens quickly 3) The cell then creates copies of the virus in
6) The body now has a defence against that virus itself
7) Antibodies and memory cells are in blood 4) It continues to do so until it explodes and
stream releases all the viruses and the process
8) If the real virus enters the bloodstream then it repeats
will easily be stopped by the antibodies 2:
9) Memory cells will quickly produce antibodies 1) They attach to a cell and replace some of the
in response cells genetic information with its own
2) When the cell divides it has the genetic
Will rapidly produce antibodies if real pathogen information stored
enters body 3) The cells multiply resulting in many cells with
Cons - vaccines don’t always work, can lead to bad that genetic information
reactions & side effects 4) Something triggers the cells and they all start
making copies of the virus within themselves
using the genetic information they have stored
5) They do so until they explode and all these
cells release many copies of the virus
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