Micro-organisms Flashcards

1
Q

what is a microorganism

A

a microorganism or microbe is an organism that is usually unicellular but can be multicellular

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2
Q

prokaryotic

A

cells that have nuclear material but no true nucleas

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3
Q

eaukaryotic

A

cells that have a true nucleus

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4
Q

akaryotic

A

have no cell with cytoplasm or nucleus

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5
Q

types prokaryotic organisms

A

bacteria and archea

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6
Q

examples of Eukaryotic organism

A

fungi and protists

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7
Q

examples of akaryotic organisms

A

viruses

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8
Q

where can microorganisms be found

A

in all parts of the biosphere where there is liquid water

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9
Q

microorganisms are critical to nutrient recycling as they act as

A

decomposes and some can fix nitrogen

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10
Q

tube

A

provides a pathway for the light from the objective to the eyepiece

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11
Q

rotating nose piece

A

a disc containing different objective lenses that can rotate to allow the different objectives to be use

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12
Q

objective (lens)

A

convex lenses of different strengths to enlarge the image

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13
Q

stage clips

A

the stage clips keep the microscope slide in position of the stage

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14
Q

diaphragm

A

can be opened and closed to allow less or more light to pass through the specimen

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15
Q

condenser

A

is a lens that focuses the light from the light source into the specimen

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16
Q

light source

A

an electric light or a mirror providing light that will be directed to the specimen

17
Q

eyepiece (ocular)

A

convex lenses to enlarge the image (magnification of 10x)

18
Q

arm

A

connect the upper part containing the lenses with the lower part containing the light source and the microscope is picked up at the arm

19
Q

stage

A

a platform that supports the microscope slide

20
Q

coarse adjustment

A

rapidly moves the stage up and down to focus the image when the smallest objective is being used

21
Q

fine adjustment

A

slowly moved the stage up and down to focus the image when longer objectives are being used

22
Q

base

A

a heavy large surface area that supports the weight of the microscope to prevent it from falling over

23
Q

what is a limitation of a light microscope

A

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)

24
Q

functioning of an electron microscope

A

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

25
Transmission electron microscope (TEM)
can enlarge a specimen, and shows the inside structure
26
scanning electron microscope (SEM)
shows the outside surface view of a solid specimen
27
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
28
Vibrio Cholera
- causes cholera - it is spread via contaminated food and water - symptoms ; profuse diarrhoea and can lead to death
29
Salmonella
invade the intestinal lining cells can cause typhoid found in water or food and raw poultry products
30
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
31
viruses
they do not posses a cell (no nucleus no cytoplasm) so they cannot be classified as living organisms
32
how are viruses named
named according to the host they infect and the symptoms they produce