12.1 And 12.2 Flashcards
What are pathogens and communicable diseases?
- these are caused by infective organisms called pathogens (microorganism that causes disease)-not all microorganisms cause disease
- These include bacteria, viruses, fungi and protoctista
- They are spread from one organism to another- so in animals they are spread from one individual species to another but they can also spread between species
What are vectors?
- carry pathogens from one organism to another, and are involved in the spread of many communicable diseases
- Common vectors include water and insects
What is bacteria and some examples? (4.1.1 a)
- They reproduce quickly via binary fission every 20 minutes
- Tuberculosis is caused by mycobacterium tuberculosis (these can go inside cell!)
- Meningitis is sometimes caused by bacteria
- Ring rot which affects tomatoes and potatoes
How can we treat bacterial diseases?
- antibiotics treat bacterial diseases
- Bacteria cultured on plate
- Clear area=zone of inhibition
- Antibiotics- more resistant bacteria can withstand antibiotic resistant and less resistant are killed
- Important to take full course of antibiotics!
What are viruses and some examples?
- non living because they require a host organism
- 0.02-0.3 micrometers in diameter
- Contains genetic material-RNA or DNA surrounded by a protein coat AKA capsid
- They also have a lipid membrane taken by the cell membrane of host cell- this is why washing hands is so effective against viruses, as it breaks down the lipid membrane
- Viruses invade living cells, where the genetic material of the virus takes over the biochemistry of the host cell to make more viruses
- Viruses reproduce rapidly and are able to evolve quickly which makes them successful pathogens
- Viruses that attack bacteria are bacteriophages- they take over the bacteria cells and use them to replicate
Examples:
- retrovirus
- Flu, corona virus, tobacco mosaic virus
- Influenza
What are protists and some examples?
- eukaryotic organisms, complex, single celled organisms
- They act as parasites, using humans and animals as there host organism and feeding on contents
- This causes devastating communicable diseases in both people and plants
- Pathogenic protists may also need a vector to transfer them to their host organism such as malaria and sleeping sickness or they can enter the body directly through polluted water
- malaria
- Potato or tomato blight
- Sleeping sickness
What is fungi and the diseases caused by fungi?
- fungal diseases are not a major problem in animals but they can cause devastation in plants
- Fungi can eukaryotic organisms are multicellular except yeast such as thrush are single-celled
- Fungi cannot photosynthesise and they digest their food extracellularly before absorbing the nutrients
- Many fungi are saprophytes which means they’re dead and feed off decaying matter
- Some fungi are parasitic feeding on living plants and animals
- When fungi reproduce they produce hyphae (tubes- many hyphae are called mycelium) which produce millions of spores which can spread over huge distances
- They also produce enzymes which digest cells
What diseases are caused by fungi?
- athletes foot (humans)
- Ring worm (cattle)
- Black Sigatoka (bananas)
What is ring rot?
ring rot- a bacterial disease of potatoes, tomatoes and aubergines which damages the leaves, tubers and fruit, destroying 80% of the crop. There is no cure, bacterial ring rot infects a field it cannot be used to grow potatoes again for at least 2 years
What is bacterial meningitis?
- Bacterial meningitis- a bacterial infection of the meninges of the brain (protective membranes on the surface of the brain) which can spread to the rest of the body causing septicaemia (blood poisoning) and rapid death affecting mainly very young children
- Can cause blotchy red/purple rash
- Can be cured by antibiotics and some forms of vaccination
What is tobacco mosaic virus?
Tobacco mosaic virus - infects tobacco plants and 150 species of plants. It damages leaves, flowers and fruit, stunting growth and reducing yield leading to crop loss. Resistant crop strains are available but there is no cure
What is potato blight?
Potato blight- caused by a fungi like protoctist. The hyphae penetrate host cells, destroying leaves, tubers and fruit causing millions of pounds worth of crop damage. There is no cure but resistant strains, careful management and chemical treatments can reduce infection risk
What is malaria?
- called by plasmodium protoctist
- Invades rbc, liver and even the brain
- Disease recurs making people vulnerable to secondary infections
- To reduce the spread of malaria we can kill mosquitoes using insecticides and removing the standing water where they breed
- Mosquito nets, window and door screens and long sleeved clothing can prevent them from biting people and spreading the disease
What is ring worm?
- fungal disease affecting mammals including cattle, dogs and humans
- Different fungi infect different species causing white, crusty infectious areas of the skin
- Anti fungal creams may be considered an effective cure
What is athletes foot?
- a human fungal disease that grows on and digests warm, moist skin between the toes. It causes cracking and scaling, which is itchy and may become sore
- Again anti fungal creams are an effective cure
What is black Sigatoka?
Black Sigatoka- a banana disease caused by the fungus which attacks and destroys the leaves, the hyphae penetrate and digest cells, turning them black causing a 50% reduction in yield. Resistant strains are being developed and fungicide treatment can control the spread of disease
What is HIV?
- Targets t-helper cells in the immune system of the body
- Gradually destroys the immune system so the body is open to other infections such as TB, pneumonia and some forms of cancer
- HIV is a retrovirus so contains RNA as its genetic material
- Influenza- a viral infection of the ciliated epithelial cells in the gas exchange system- kills them leaving the airways open for secondary infections such as pneumonia
- Flu viruses are able to mutate yearly
- Vulnerable groups are given a flu vaccine annually to protect against ever changing strains
- There is no cure
