MIBO 3500E Final Exam with complete
solutions
Millimeter (mm)
10^-3 m (1000 mm in a m)
Micrometer (µm)
10^-6 m (1000 µm in a mm)
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Nanometer (nm)
10^-9 m (1000 nm in a µm)
Microbes
Organisms and acellular agents too small to be seen by the unaided eye
~100-200 µm
What is the limit of detection for the unaided eye?
10,000 µm
What is the width of a fingernail?
2 µm
What is the length of Escherichia coli (E. coli)?
0.2 µm
What is the length of T4 phage (virus that infects bacteria)?
There are 1000 nm in 1 µm so 2 µm is equivalent to 2000 nm. Both cells are the same
sisze.
You have an E. coli bacterial cell that is 2 µm and a Salmonella bacterial cell that is
2000 nm. Which cell is larger?
, Microbial size contradictions
1. Supersize microbial cells: outliers we can sometimes see (ex: Thiomargarita
namibiensis is 0.7 mm or larger, some giant amoebas can be seen by unaided eye)
2. Microbial communities: in some cases we can see (ex: mushrooms easily seen
with unaided eye)
3. Viruses: considered acellular agents, not living; microorganisms but not cells...just
nucleic acid surrounded by protein coat
Robert Hooke (1635-1703)
-Built the first compound microscope
-Used it to observe mold, fleas, cork: looking at world in new way, could see details of
animals, plants, soil
-Published Micrographia: intricate drawings of what he saw, believe now may have
been fungus
-Coined the term "cell"
-First scientist credited with describing microorganism at cellular level
Antonie von Leeuwenhoek (1632-1723)
-Built single-lens magnifiers
-First to observe single-celled microbes: "discovered" bacteria (published drawings and
descriptions)
-He called them "small animals": "animolecules" (had no point of reference)
Spontaneous generation
The controversial theory of living organisms from non-living matter (life will
spontaneously arise from non-living) debated by many historical scientists
-Decaying meat "produced" maggots
-Sand "produced" oysters and clams
-Used as evidence for microorganisms but many disagreed
Francesco Redi (1626-1697)
Showed that maggots on decaying meat came from fly eggs deposited on the meat, not
from the meat itself
-Published that this refuted spontaneous generation
-Life (maggots) came from other life (flies), further analysis showed microscopic life
associated with decaying meat but couldn't be explained at the time
Lazzaro Spallanzani (1729-1799)
Showed that nutrient broth sealed in flasks and then boiled had no growth of
microorganisms
-Disproved spontaneous generation; microbial life must be coming from outside
container, not non-living broth
-Conclusions: cellular fission of microbes in broth...showed microbes do have "parents"
Louis Pasteur (1822-1895)
Showed that nutrient broth heated in swan neck flasks had no growth of
microorganisms, but broken necked flasks did
solutions
Millimeter (mm)
10^-3 m (1000 mm in a m)
Micrometer (µm)
10^-6 m (1000 µm in a mm)
Previous
Play
Next
Rewind 10 seconds
Move forward 10 seconds
Unmute
0:00
/
0:15
Full screen
Brainpower
Read More
Nanometer (nm)
10^-9 m (1000 nm in a µm)
Microbes
Organisms and acellular agents too small to be seen by the unaided eye
~100-200 µm
What is the limit of detection for the unaided eye?
10,000 µm
What is the width of a fingernail?
2 µm
What is the length of Escherichia coli (E. coli)?
0.2 µm
What is the length of T4 phage (virus that infects bacteria)?
There are 1000 nm in 1 µm so 2 µm is equivalent to 2000 nm. Both cells are the same
sisze.
You have an E. coli bacterial cell that is 2 µm and a Salmonella bacterial cell that is
2000 nm. Which cell is larger?
, Microbial size contradictions
1. Supersize microbial cells: outliers we can sometimes see (ex: Thiomargarita
namibiensis is 0.7 mm or larger, some giant amoebas can be seen by unaided eye)
2. Microbial communities: in some cases we can see (ex: mushrooms easily seen
with unaided eye)
3. Viruses: considered acellular agents, not living; microorganisms but not cells...just
nucleic acid surrounded by protein coat
Robert Hooke (1635-1703)
-Built the first compound microscope
-Used it to observe mold, fleas, cork: looking at world in new way, could see details of
animals, plants, soil
-Published Micrographia: intricate drawings of what he saw, believe now may have
been fungus
-Coined the term "cell"
-First scientist credited with describing microorganism at cellular level
Antonie von Leeuwenhoek (1632-1723)
-Built single-lens magnifiers
-First to observe single-celled microbes: "discovered" bacteria (published drawings and
descriptions)
-He called them "small animals": "animolecules" (had no point of reference)
Spontaneous generation
The controversial theory of living organisms from non-living matter (life will
spontaneously arise from non-living) debated by many historical scientists
-Decaying meat "produced" maggots
-Sand "produced" oysters and clams
-Used as evidence for microorganisms but many disagreed
Francesco Redi (1626-1697)
Showed that maggots on decaying meat came from fly eggs deposited on the meat, not
from the meat itself
-Published that this refuted spontaneous generation
-Life (maggots) came from other life (flies), further analysis showed microscopic life
associated with decaying meat but couldn't be explained at the time
Lazzaro Spallanzani (1729-1799)
Showed that nutrient broth sealed in flasks and then boiled had no growth of
microorganisms
-Disproved spontaneous generation; microbial life must be coming from outside
container, not non-living broth
-Conclusions: cellular fission of microbes in broth...showed microbes do have "parents"
Louis Pasteur (1822-1895)
Showed that nutrient broth heated in swan neck flasks had no growth of
microorganisms, but broken necked flasks did
