12.1 Animal And Plant Pathogens Flashcards
Communicable diseases
Diseases that can be passed from one organism to another, of the same or different species
What are communicable diseases caused by?
Pathogens
Types of pathogens
Bacteria
Viruses
Fungi
Protocista
What are vectors? Eg…
Carry pathogens from one organism to another
Eg - water and insects
Bacteria
Prokaryotes
Do not have membrane bound organelles or nucleus
How can bacteria be classified?
By their basic shapes
Their cell walls
Different shapes of bacteria
Bacilli - rod shaped Cocci - spherical Vibrios - comma shaped Spirilla - spiralled Spirochaetes - corkscrew
Two types of bacterial cell walls
Gram positive
Gram negative
Gram positive bacteria
Look purple blue under microscope
High amount of peptidoglycan
Gram negative bacteria
Appear red under microscope
Lower amount of peptidoglycan
Virus
Non living infectious agents
0.02-0.3μm - very small
Basic structure of viruses
Genetic material (DNA or RNA) surrounded by protein
How do viruses work?
Invade living cells - where genetic material of viruses integrates into host cell DNA to replicate the virus
Virus reproduce rapidly and evolve by developing adaptations to the host
What are bacteriophages?
Viruses that attack bacteria
They take over bacterial cells and use them to replicate - destroying the bacteria at the same time
Protocista
Eukaryotic organisms with a variety of feeding methods
Protists that cause disease are parasitic and use animals/people as host organism
How do Protocista enter the body?
Need a vector to transfer them to the host
Or enter the body through polluted water
Fungi
Eukaryotic organisms (can be uni or multicellular)
How do fungi gain energy?
Cannot photosynthesise and digest food extra cellularly before absorbing nutrients
Most fungi are saprophytes - feed on dead or decaying matter
Some are parasitic - feed on living plants and animals
Why are fungal diseases bad for plants?
They often affect the leaves of plants, stop photosynthesis and can quickly kill the plant
How do fungi reproduce?
They produce many spores that can travel long distances so they can spread rapidly and widely through crops
How do viruses attack host tissues?
Viruses take over cell metabolism
Viral genetic material gets into the host cell and is inserted into the host DNA
Virus uses the host cell to make new viruses, which burst out of the cell and spread to infect other cells
How do Protocista attack host tissues?
Take over cells and break them open
They do not take over the genetic material
They digest and use the cell contents as they reproduce
How do fungi attack host tissues?
Digest living cells and destroy them
The response of the body to the fungus and this causes the symptoms of disease
Toxins and effect on host tissues
Break down cell membranes
Damage/inactivate enzymes
Interfere with host cell genetic material
