Micro-organisms Flashcards
what is a microorganism
a microorganism or microbe is an organism that is usually unicellular but can be multicellular
prokaryotic
cells that have nuclear material but no true nucleas
eaukaryotic
cells that have a true nucleus
akaryotic
have no cell with cytoplasm or nucleus
types prokaryotic organisms
bacteria and archea
examples of Eukaryotic organism
fungi and protists
examples of akaryotic organisms
viruses
where can microorganisms be found
in all parts of the biosphere where there is liquid water
microorganisms are critical to nutrient recycling as they act as
decomposes and some can fix nitrogen
tube
provides a pathway for the light from the objective to the eyepiece
rotating nose piece
a disc containing different objective lenses that can rotate to allow the different objectives to be use
objective (lens)
convex lenses of different strengths to enlarge the image
stage clips
the stage clips keep the microscope slide in position of the stage
diaphragm
can be opened and closed to allow less or more light to pass through the specimen
condenser
is a lens that focuses the light from the light source into the specimen
light source
an electric light or a mirror providing light that will be directed to the specimen
eyepiece (ocular)
convex lenses to enlarge the image (magnification of 10x)
arm
connect the upper part containing the lenses with the lower part containing the light source and the microscope is picked up at the arm
stage
a platform that supports the microscope slide
coarse adjustment
rapidly moves the stage up and down to focus the image when the smallest objective is being used
fine adjustment
slowly moved the stage up and down to focus the image when longer objectives are being used
base
a heavy large surface area that supports the weight of the microscope to prevent it from falling over
what is a limitation of a light microscope
even with perfect illumination as well as a perfect lense a light microscope can’t distinguish an object smaller then half a wave length of light (we then use an electron microscope)
functioning of an electron microscope
electrons are speeded up in a vacuum until there wavelength is extremely short, beams of this is focused on a cell sample that is absorbed or scattered by the cells to form an image of an electron
Transmission electron microscope (TEM)
can enlarge a specimen, and shows the inside structure
scanning electron microscope (SEM)
shows the outside surface view of a solid specimen
what is the drawback of an electron microscope
since no living specimen can survive under the high vacuum they cannot show the ever changing movements that characterise a living cell
Vibrio Cholera
- causes cholera
- it is spread via contaminated food and water
- symptoms ; profuse diarrhoea and can lead to death
Salmonella
invade the intestinal lining cells
can cause typhoid
found in water or food and raw poultry products
Clostridium botulinum
- Grows in the absence of oxygen (botulism)
- produces one of the most dangerous toxins known to man
- comes from sausages and canned food
- symptoms; Flaccid paralysis 18-36 hours after ingestion and causes respiratory paralysis
viruses
they do not posses a cell (no nucleus no cytoplasm) so they cannot be classified as living organisms
how are viruses named
named according to the host they infect and the symptoms they produce
