B3-Infection and response Flashcards
What is a pathogen?
A micro-organism that causes disease
What is the difference between communicable and non-communicable diseases?
Communicable diseases can be passed from one person to another
Non-Communicable diseases cannot be transmitted from one person to another
What are the 4 types of pathogens?
- Viruses
- Bacteria
- Fungi
- Protists
How do bacteria cause disease?
They divide rapidly (called binary fission) and in the process produce toxins-this can make the host feel ill and can damage cells
What are some features of viruses?
A protien coat with a strand of DNA inside
How do viruses cause disease?
They enter the body’s cells and once replicating, they explode the cell-the damaged cells cause the symptoms
How are pathogens spread (3)
- By air
- Direct contact
- By water
How do you sterilise the inoculating loop before use?
By heating it until it is red hot
Why should cultures be incubated at a maximum temperature of 25°?
To reduce the likelihood of pathogens growing that might be harmful to humans
Why should the petri dish only be partly sealed with tape?
To prevent microorganisms from the air from contaminating the culture and to allow some air in to prevent harmful anaerobic bacteria from growing
Why is agar gel needed when growing bacteria in petri dishes?
It contains carbohydrate as an energy source, some minerals and nitrogen so the bacteria can make proteins
Why are petri dishes stored upside down?
To stop condensation falling on the agar surface
What are the ways to protect bacterial growth?
- To raise or lower the temperature
- Using chemicals such as disinfectants, antiseptics (safe to use on our skin), antibiotics (safe to use in our bodies)
How do you calculate the effect of disinfectants and antibiotics on bacterial growth?
By measuring the area of the zone of inhibition
How can the spread of disease be prevented? (4)
- Simple hygiene measures
- Destroying vectors
- Vaccination
- Isolating infected individuals
What are 3 examples of viral diseases?
- Measles
- HIV/AIDS
- Tobacco mosaic virus
How are measles spread?
By droplet infection
What are the symptoms of measles?
A fever and a red skin rash-it can also cause blindness and brain damage and be fatal
How can measles be cured/prevented?
It can’t be cured however vaccination and isolation of patients prevent the spread
How is HIV spread?
By sexual contact or by exchange of bodily fluids
What are the symptoms of HIV?
Mild flu like sumptoms
What does HIV do?
It attacks the immune cells and after the initial mild illness it is hidden inside the immune system unil the immune system is so badly damaged that it can no-longer deal with infections or certain cancers-now it is called AIDS
How can we prevent the spread of HIV?
By using condoms, not sharing needles, screening blood used for transfusions and bottle feeding children in the case of HIV-positive mothers
How is Tobacco mosaic virus spread?
Via contact and vectors
What are some symptoms in plants of Tobacco mosaic virus?
It causes a ‘mosaic pattern’ of discoloration on the leaves as the virus destroys the cells-this reduces photosynthesis and affects the growth of the plant
How can the spread Tobacco mosaic virus be prevented?
Good field hygiene and good pest control
What are 3 examples of bacterial diseases?
- Salmonella
- Gonorrhoea
- Plant bacterial diseases-Agrobacterium tumefaciens
How is salmonella spread?
Through undercooked food and poor hygiene
What are some symptoms of Salmonella?
Fever, Abdominal cramps, Diarrhoea
How can the spread of Salmonella be reduced?
Vaccinating poultry against it, Avoid washing raw chicken, Wash hands after handling raw chicken
How is Gonorrhoea spread?
Through unprotected sexual contact with an infected person
What are symptoms of Gonorrhoea?
Thick yellow or green discharge from genitals, pain while urinating, long term pelvic pain, infertility and ectopic pregnancies
How can the spread of Gonorrhoea be reduced?
By limiting sexual partners and using barrier contraception
How does Agrobacterium tumefaciens infect plant cells?
By inserting plasmids into plant cells