infection and response

• What are pathogens?

  Pathogens are microorganisms that enter the body and cause disease.
• What do pathogens cause?

  Pathogens cause communicable disease that can be easily spread.
• Both plants and animals can be infected by pathogens.
• Pathogens can either be bacteria, viruses, protists or fungi.
• Bacteria are very small cells ( 1/100th the size of your body cells) which can reproduce rapidly inside your body.
• How do bacteria make you feel ill?

  Bacteria make you feel ill by producing toxins that damage your cells and tissues and reproducing quickly, damaging more cells.
• Viruses reproduce rapidly inside your body.
• How does a virus make you feel ill?

  They live inside your cells and replicate themselves using the cells machinery to produce many copies of themselves. The cell usually just bursts, spreading the virus. The damage from the cell is what causes you to feel ill.
• Protists are single celled. They are eukaryotic. Some protists are parasites. They live on or inside other organisms and can scan cause them danger.
• some fungi are single celled.
• Pathogens can be spread through many ways such as water, air and direct contact.
• How are pathogens spread by water?

  By drinking or bathing in contaminated water e.g. cholera is a bacterial infection that is spread by drinking the water that is infected with others diarrhoea.
• How are pathogens spread by air?

  Pathogens can be carried in the air and then can be breathed in.Some airborne pathogens are carried in the air in droplets produced when you cough or sneeze (droplet infection) e.g. influenza/flu
• Viruses

  • Not cells, not living, but considered organisms
  • About 10,000 times smaller than animal cells
  • Can't reproduce by themselves, but can use a host cell's machinery to make copies of themselves
  • Can burst the host cell to release new viruses to infect other cells
• Viruses

  • Damage host cells, making the host feel ill
• Viral diseases covered

  • Measles
  • HIV
  • Tobacco mosaic virus
• Measles virus transmission

  Spread by droplets when an infected person coughs or sneezes
• Measles


  • Causes a red rash and fever
  • Serious and sometimes fatal
  • Rare in UK due to vaccination
• HIV transmission

  Spread by sexual contact or exchanging bodily fluids like blood
• HIV


  Human immunodeficiency virus, affects the immune system
• HIV infection progression

  1. Initial flu-like symptoms

  2. Immune system gradually weakens

  3. Leads to AIDS when immune system can't cope
• AIDS


  Disease or syndrome where the immune system can't cope with infections and cancers
• HIV treatment

  • Antiretroviral drugs can prevent virus replication, allowing normal life
• Tobacco mosaic virus (TMV)


  • Virus that affects plants like tobacco and causes mosaic patterns on leaves
  • Disrupts photosynthesis, reducing plant growth
• Tobacco mosaic virus only affects certain plant species
• Measles, HIV and TMV are viral diseases.
• Measles is spread by droplet infection from an infected persons sneeze or cough.
• what are some symptoms of measles?

  a red skin rash and a high fever.
• How do you control the spread of measles?

  Vaccine. (no cure)
• What type of pathogen is measles?

  Measles is a virus.
• What are the symptoms of TMV?

  stunted growth (cannot synthesise), yellow and brown spots on leaves.
• How is TMV transmitted?

  Touch, contaminated leaves and vectors.
• How do you control the spread of TMV?

  Remove infected leaves and clean tools.
• What pathogen causes TMV?

  Virus.
• What are the symptoms of gonorrhoea?

  thick yellow/green discharge from vagina/penis, pain when urinating.
• how is gonorrhoea spread?

  sexual contact.
• how do you control the spread or gonorrhoea?

  using condoms, limiting sexual partners.
• Which pathogen causes gonorrhoea?

  Bacteria, can be treated with antibiotics.
• What are the symptoms of salmonella?


  Abdominal cramps, diarrhoea, vomiting and fever.
• how is salmonella spread?

  contaminated food, food that has been prepared in unhygienic conditions.