Animal And Plant Pathogens Flashcards
what are pathogens?
an organism which causes disease.
what are the four types of pathogens?
- bacteria
- fungi
- virus
- protoctista
how many people die each year from communicable diseases?
13 million people
do all bacteria cause disease?
no
what type of cell are bacteria?
prokaryotes
what are the two ways of classifying bacteria?
- by their basic shapes.
- by their cell walls.
what are the different basic shapes that bacteria may be?
- rod shaped (bacilli)
- spherical shaped (cocci)
- comma shape (vibrios)
- spiralled shape (spirillia)
- corkscrew (spirochaetes)
what are the two main types of bacterial cell walls?
- gram positive bacteria
- gram negative bacteria
how can you determine the type of bacterial cell wall bacteria has?
gram staining.
why is t useful to know the type of cell wall bacteria has?
the type of cell wall affects how bacteria react to different antibiotics.
what are antibiotics?
compounds that kills or inhibits the growth of bacteria.
are viruses alive?
no. they are non-living.
what diameter do viruses have?
0.02-0.03 um in diameter.
how much smaller in length are viruses compared to bacteria?
50 times smaller in length.
what is the basic structure of a virus?
some genetic material (DNA or RNA) surrounded by protein.
how do viruses infect cells?
they invade living cells and the genetic material of the virus takes over the healthy cell to make other viruses. they reproduce rapdly until the cell bursts and genetic information is spread to other healthy cells. they evolve by developing adaptions.
are all naturally occuring viruses pathogenic?
yes.
what are bacteriophages?
when a virus infects bacteria.
how are bacteriophages used now?
to identify and treat some diseases. they are also useful for scientific research.
what do scientists consider to be the ultimate parasites?
viruses.
what is another name for protoctista?
protista
what are protoctista?
a group of eukaryotic organisms with a wide variety of feeding methods.
are all protoctista pathogenic?
no - only a small percentage are pathogenic.
are protoctista parasitic?
yes
what does parasitic mean?
they use people and animals as their host organism.
how are protoctista trasferred between their hosts?
- vectors.
- may enter the body directly as a result of polluted water.
are fungal problems worse for humans or plants?
plants.
are fungi eukaryotic or prokaryotic?
eukaryotic and often multicellular.
are the fungi that cause yeast multicellular or unicellular?
single celled.
are fungi saprophytes?
yes
what does it mean to be a saprophyte?
they feed on dead and decaying matter.
how do fungi digest their food?
they cannot photosynthesise and digest their food extracellularly before absorbing the nutrients.
which type of fungi causes disease?
parasitic fungi
how does fungi kill a plant?
fungal infections often affect the leaves of a plant so they stop them from photosynthesising and so can quickly kill a plant.
how does fungi spread?
they produce millions of tiny spores when they reproduce which means they can spread rapidly and widely through crop plants.
what causes the symptoms of disease?
- pathogen damages the tissues of the host organism.
- the body responds to the damage.
how do viruses attack and damage host tissues?
viruses take over cell metabolism. viral genetic material gets into the host cell and is inserted into the host DNA. the virus uses this cell to make new viruses which burst out of the cell, destroying the cell and infecting others.
how do protoctista damage host cells?
they take over cells and break them open as the new generation emerge. they do this to digest and use cell contents as they reproduce, rather than taking over the genetic material of the cell. malaria is an example.
how do fungi damage host cells?
fungi digest living cells and destroy them.
which pathogens may produce toxins?
- bacteria
- fungi
how do bacterial toxins damage cells?
- they may break down cell membrane
- they may inactivate enzymes
- some interfere with the host cell genetic material so cells cannot divide.
