deck_5807070 Flashcards
What is a pathogen?
Organisms that case disease
What is a host?
The organism that pathogens live in, they create a good habitat in which microorganisms can live so many live in or on body of other organisms
How do pathogens live?
By taking nutrition from their host, but this causes damage to the host
What kingdom do bacteria belong to?
Prokaryote
What are bacteria like?
Smaller than eukaryotic cells, but reproduce rapidly (every 20 minutes in right conditions)
How do bacteria cause disease?
By damaging cells or by releasing waster products/toxins that are toxic to the host
How do bacteria damage plants?
It lives in vascular tissues and cause blackening and death of these tissues
What are common fungal infections?
Where fungus lives in skin of animal and where its hyphae forms a mycelium, grow under skin surface, fungus sends out specialised reproductive hyphae which grow to surface of skin releasing spores causing redness and irritation
What happens with plants and fungus?
It lives in the vascular tissue where it gains nutrients, hyphae releases extracellular enzymes (eg cellulases) to digest surrounding tissue, causing decay. Leaves become mottled, curl up, shrivel then die, and fruit and storage organs such as tuber turn black and decay
How do viruses work?
Invade cells and take over genetic machinery and other organelles, then cause cell to manufacture copies of the virus until host eventually bursts, releasing many new viruses to infect healthy cells
What are protoctista?
Cause harm by entering host cells and feeding on the contents as they grow, they are animal-like protoctists
What are examples of diseases caused by bacteria?
Tuberculosis, bacterial meningitis and ring rot in plants
What is tuberculosis?
Disease affecting many parts of body such as lungs, that kills cells and tissues, caused by Mycobacterium tuberculosis and M.bovis
What is bacterial meningitis?
Infection of meninges where membranes around brain and spinal cord swell causing brain and nerve damage, caused by Neisseria meningitidis or Streptococcus pneumonia
What is ring rot (plants)?
Ring of decay in vascular tissue of potato tuber or tomato with leaf wilting, caused by clavibacter michiganensis subsp. sepedonicus
What are diseases caused by viruses?
HIV/AIDS, influenza and tobacco mosaic virus
What is HIV/AIDS?
Attacks cells in immune system and compromises immune response, caused by human immunodeficiency virus
What is influenza?
Attacks respiratory system and causes muscle pains and headaches, caused from family Orthomyxoviridae-‘flu’ viruses
What is tobacco mosaic virus?
Causes mottling and discolouration of leaves, caused by tobacco mosaic virus
What are diseases caused by fungus?
Black sigatoka (bananas), ringworm (cattle) and athlete’s foot
What is black sigatoka (bananas)?
Causes leaf spots on banana plants reducing yield, caused by Mycosphaerella fijiensis
What is ringworm (cattle)?
Growth of fungus in skin with spore cases erupting through skin to cause rash, caused by Trichophyton verrucosum
What is athlete’s foot?
Growth under skin of feet-particularly between toes, caused by Trichophyton rubrum
What are diseases caused by protoctistan?
Blight (tomatoes and potatoes), and malaria
What is blight (tomatoes and potatoes)?
Affects leaves and potato tubers, caused by phytophthora infestans
What is malaria?
Parasite in blood that causes headache and fever that can progress to coma and death, caused by Plasmodium falciparum, P.vivax, P.Ovale, P.malariae
What is the life cycle of pathogens?
Travel from one host to another (transmission), enter host’s tissues, reproduce, leave host’s tissues
What are two types of transmission between animals?
Direct and indirect transmission
What is direct transmission?
Most common form where pathogens pass from host to new host with no intermediary
What are four factors affecting direct transmission?
Direct physical contact, faecal-oral transmisison, droplet infection and transmission by spores
What are social factors that can affect transmission?
Overcrowding, poor ventilation, poor health (especially if someone has HIV/AIDS), poor diet, homelessness and living or working with people who have migrated from areas where a disease is more common
What is indirect transmission?
Some pathogens transmitted indirectly via a vector, which is another organisms used by pathogen to gain entry to a host
What is the vector in malaria?
The female anopheles mosquito which bites the human host, allowing the plasmodium parasite that caused malaria to enter
What is the cycle of malaria?
Uninfected person is bitten, plasmodium migrates to liver, plasmodium migrates to blood, person has malaria, gametes of plasmodium in blood, female anopheles mosquito sucks the blood, plasmodium develops and migrates to a mosquito’s salivary glands, then it repeats
How can direct transmission occur in plants?
Pathogens in soil especially if the plant has been damaged by movement or animal, fungi producing spores due to sexual/asexual reproduction (airborne transmission), and pathogens inside plants that infect vascular tissue, leaves, which fall, then infect soil again, also in seeds and fruit it infects all offspring
How can indirect transmission occur in plants?
As a result of insect attack, spores/bacteria attach to burrowing insect which attacks infected plant, then transmits the disease eg dutch elm disease carried by scolytus multistriatus
Why are many diseases more common in warmer climates?
Many protoctists, bacteria and fungi can grow and reproduce more rapidly in warm and moist conditions
What happens to these pathogens in cooler climates?
They can be damaged or killed, and their ability to grow and reproduce is reduced
