module 4 - 12.1 plant and animal pathogens Flashcards
what are communicable diseases caused by?
infective organisms called pathogens
what are the 4 types of pathogens?
- bacteria
- viruses
- fungi
- protoctista
what is a communicable disease?
can be passed from one organism to another
what are vectors?
carry pathogens from one organism to another
- common vectors are water/insects
what are bacteria?
prokaryotes - so have different cell structure to eukaryotic organisms they infect
what 2 ways are bacteria classified?
- by their basic shape
- by their cell walls
how are bacteria classified by their basic shape?
- may be rod shaped (bacilli)
- spherical (cocci)
- comma shaped (vibrios)
- spiralled (spirilla)
- corkscrew (spirochaetes)
what are the two main types of bacterial cell walls?
- gram positive cell walls (look purple-blue under light microscope)
- gram negative cell walls (look red under light micorscope)
useful as type of cell wall affects how bacteria reacts to antibiotics
what are viruses?
non-living infectious agents
what is the basic structure of a virus?
genetic material (DNA/RNA) surrounded by protein
what type of viruses are pathogenic?
all naturally occurring viruses
what are protoctista?
- eukaryotic organisms
- some are pathogens
- they use people/animals as their host
- may need a vector to transfer to hosts
what are fungi?
- eukaryotic organisms - usually multicellular
- example - yeast (unicellular)
- parasitic fungi affect living plants and animals
- cant photosynthesise so digest food extracellularly
- many are saprophytes - feed on dead and decaying matter
- pathogenic fungi cause diseases
how can fungi kill a plant?
fungal infections affect leaves on plants - cant photosynthesise so die
what happens when fungi reproduce?
produce millions of tiny spores that can spread huge distances - rapidly
what ways do different pathogens attack and damage host tissues?
- viruses take over cell metabolism
- some protoctista take over cells & break them open - dont take over genetic material
- fungi digest living cells and destroy them
how do protoctista take over cells?
digest and use cell contents as they reproduce
how do fungi cause diseases?
colonising and destroying tissues
what do toxins do?
- poison/damage host cells - cause disease
- break down cell membranes
- damage inactive enzymes
- interfere with host cell genetic material - cells cannot divide
what are toxins?
- produced by bacteria
- by-product of normal functioning bacteria
