Flashcards in Animal and plant pathogens Deck (18):
What is a communicable disease?
-Disease passed from one organism to another.
-Caused by pathogens.
What are pathogens?
-Microorganisms that cause disease.
-4 types; bacteria, virus, protocista and fungi.
What are vectors?
-Carry pathogens from one organisms to another.
-E.g. insects and water.
What are the characteristics of bacteria?
-No membrane-bound nucleus or organelles.
-Only a small proportion of bacteria cause disease.
How can bacteria be classified?
-By their shape; e.g. rod shaped (bacilli), spiralled (spirila), spherical (cocci).
-By cell walls; Gram positive bacteria look purple/blue under light microscope, and Gram negative bacteria look red.
Why is gram staining useful?
-Shows how type of cell wall affects how bacteria react to different antibiotics.
What are antibiotics?
-Compound that kills or inhibits the growth of bacteria.
What are the characteristics of viruses?
-Non-living infectious agent.
-50 times smaller that average bacterium.
-Basic structure is genetic material surrounded by protein.
How do viruses cause disease?
-Invade living cells and reproduce.
-Take over bacterial cells and use them to replicate.
What else can viruses destroy?
-Bacteria, and they are known as bacteriophages.
What are the characteristics of protoctista?
-Wide variety of feeding methods.
-Include single-celled and cells grouped in colonies.
How do protoctista cause disease?
-Use people or animals as their host organisms.
What is a host?
-Organism or cell that carries the pathogen.
What are the characteristics of fungi?
-Major problem in plants rather than animals.
-Cannot photosynthesise or digest food extracellulary.
-They are saprophytes so feed on dead matter.
How do fungi cause disease?
-Affect plant leaves so stop them photosynthesising and kill the plant.
-Produce millions of spores.
What are the two modes of pathogen action?
-Damaging the host tissue directly.
-Producing toxins which damage host tissues.
How do pathogens damage host tissue directly?
-Viruses take over cell metabolism, viral genetic material inserted into hosts DNA, new viruses are made and burst out of cell which destroys it and spreads to infect other cells.
-Protoctista break open cells and digest cell contents and reproduce.
-Fungi digest and destroy living cells.