 In 1665, ________ ________
reported that living things
were composed of little
boxes or cells.
 1673-1723, _______ ____
_______________– first to
describe live microorganisms
that he observed in teeth
scrapings and pond water
 The hypothesis that living organisms arise from nonliving
matter is called _______________ _________________.
According to spontaneous generation, a “_________
_______” forms life.
 The alternative hypothesis, that the living organisms
arise from preexisting life, is called ______________.
 In 1858, Rudolf ____________ said that cells arise from
preexisting cells.
 Cell Theory: All living things are composed of _________
and come from preexisting ___________.
 Beginning in 1668, experiments were conducted to either
prove or disprove spon gen.
 But before we get into that, let’s talk about experimental
design. Some terms:
 Control – something that is used as a constant and unchanging
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
standard of _______________ in an experiment
Variable – factor, trait, condition, etc that ___________in an
experiment
Manipulated/Independent variable – variable that is changed
(manipulated) by the scientist; only one of these in an experiment
Responding/Dependent variable – variable that responds to and
depends upon the ___________________ variable
Experimental group - group in an experiment that receives the
_____________________ variable
Control group – group in an experiment that does NOT receive the
_____________________ variable
 Chemists working for LiveLonger Pharmaceuticals believe that
they have developed a drug that will lengthen human life. This
potential drug needs to be tested before LiveLonger can apply for
a patent from the Food and Drug Administration for production
of their life-lengthening drug.
 Research scientists from LiveLonger test the drug as follows:
 5,000 individuals involved; 2500 60-year-old non-smoking men and
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
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2500 60-year-old non-smoking women
50% are given a pill containing the drug; 50% are given a placebo
Study conducted over a five-year period
Controls?
Manipulated variable?
Experimental design (2:39)
Responding variable?
Experimental group?
Control group?
•1668: Francesco Redi (biogenesis) placed decaying meat in
nine jars then made these observations:
Conditions
3 sealed jars
3 open jars
Results
No maggots on the
meat
Maggots on the meat
3 jars covered with fine No maggots on the
net
meat
Where did the maggots come from?
What was the purpose of the open jars?
What was the manipulated variable?
•1745: John Needham (spon gen) put boiled nutrient
broth into flasks.
Conditions
Results
Nutrient broth
Microbial growth
boiled, poured into
flasks, and then
sealed
Where did the microbes come from?
What error did he make?
•1767: Lazzaro Spallanzani (biogenesis) boiled
nutrient solutions in sealed flasks.
Conditions
Results
Nutrient broth placed No microbial growth
in flask, sealed, then
boiled
Needham claims, “The ‘vital force’ was
destroyed!”
•1861: Louis Pasteur (biogenesis) demonstrated that
microorganisms are present in the air.
Conditions
Results
Nutrient broth placed
in flask, boiled, not
sealed
Nutrient broth placed
in flask, sealed, then
boiled
Why the difference?
Microbial growth
No microbial growth
 1864-1865: Pasteur boiled broth in open swan-necked
flasks and let the flasks sit for a __________. No
__________ grew in the broth. He then broke off the
necks and within a few hours the flasks were teeming
with _________________.
Part Two: Microscopy
History of the Microscope (4:40)
 A ________ __________
has only one lens.
 ____ _______________
was obsessed with lens
grinding. He ground
single lenses that could
magnify _____x; they
were by far the
________ in the world
at that time.
Leeuwenhoek Video (2:00)
 1595: First ____________
microscope; made by
Hans and Zaccharias
Janssen
 _____ lenses: one at the
top and one at the
bottom
 Poor __________ and low
__________, but it paved
the way
 In a ______________
microscope the image
from the objective lens
is ______________ again
by the ocular lens.
 Total magnification =
_____ lens  _____ lens
 _______________ is the
ability of the lenses to
distinguish two points.
 A microscope with a resolving
power of 4nm can distinguish
between two points ≥ 4nm.
If less than 4nm apart, then
the two points appear as one.
 The better the ___________,
the finer the detail.
 Visible light, because of its
long _____________, limits
light microscopes to _____x.
 Uses _________ instead of ________.
 The shorter ____________ of electrons gives far
greater ____________ than visible or UV light and can
therefore show the smallest objects known.
 Ultrathin sections of specimens must be used.
 Electrons pass through specimen, then an
____________________ lens to a screen or film.
 Internal chamber is a ___________.
How a TEM works
(1:48)
 10,000-100,000 (5,000,000x max)
 Resolution 2.5 nm
 Great for examining viruses and internal cellular
structures
 An electron gun produces a beam of ___________ that
_________ the surface of a whole specimen.
 100-10,000x (300,000x max)
 Resolution 20 nm
 Great for examining surface features
Individual silicon atoms
 Scanning tunneling
microscope uses a
metal __________ to
__________ the surface
of a specimen.
 Produces an image that
reveals the ridges and
depressions of
individual _________
 Resolution: 1/100 of an
atom!!
 Most _____________
microscope on earth!
“Molecular Man”
Image made
from scanning
28 CO molecules
on platinum
From the simple….
(couple of thousand $$)
to the complex!
(hundreds of thousands)