12.1 ANIMAL AND PLANT PATHOGENS Flashcards
1
Q
what are communicable diseases caused by?
A
- infective organisms known as pathogens
2
Q
what do pathogens include?
A
- bacteria
- viruses
- fungi
- protoctista
3
Q
what is a communicable disease?
A
- a disease that can be passed from one organism to another
4
Q
what are vectors?
A
- things that carry pathogens from one organism to another
5
Q
bacteria can be classed in two ways, what are these?
A
- by their basic shapes
- by their cell walls
6
Q
what are basic shapes of bacteria?
A
- rod shaped (bacilli)
- spherical (cocci)
- comma shaped (vibrios)
- spiralled (spirilla)
- corkscrew (spirochaetes)
7
Q
what are the two main types of bacterial cell walls?
A
- Gram Positive Bacteria (purple blue under a light microscope)
- Gram Negative Bacteria (appear red)
This is useful as it tells us how different bacteria react to different antibiotics.
8
Q
What are viruses?
A
- non-living infectious agents
- basic structure is genetic material surrounded by protein
- invade living cells (host cells)
- reproduce rapidly
- pathogenic
- some attack bacteria (bacteriophages)
- ‘parasites’
9
Q
what are protoctista?
A
- group of eukaryotic organisms with a wide variety of feeding methods
- include single-celled organisms and grouped cells (colonies)
- parasitic (use host organisms) and pathogenic
- pathogens may need vectors
10
Q
what are fungi?
A
- eukaryotic organisms, often multicellular
- yeast (i.e. thrush) are single celled
- cannot photosynthesise so digest food extracellularly before absorbing the nutrients
- many are saprophytes (feed on dead and decaying matter)
- some are parasitic and some are pathogenic
- produce millions of spores which spread rapidly and widely
11
Q
What are the 3 modes of actions for pathogens?
A
- viruses take over cell metabolism
- protoctista take over cells and break them open as a new generation emerges
- fungi digest and destroy living cells
12
Q
how do viruses take over the cell metabolism?
A
- viral genetic material gets into host cell and is inserted into the host DNA
- virus then uses the host cell to make new viruses which then burst out of the cell, destroying it
- they then spread to infect other cells
13
Q
how do protoctista take over cells?
A
- do not take over genetic material of the cell
- simply digest and use the cell contents as they reproduce
- i.e. malaria
14
Q
what are toxins?
A
- most bacteria produce them
- poison/ damage the host cells by breaking down the cell membranes
- some damage or inactivate enzymes and some interfere with the host cell genetic material so the cells cannot divide
- by-product of normal functioning of the bacteria
