in 1665, ________ ________ reported that living things were composed of little boxes or cells....
TRANSCRIPT
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
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 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? Responding variable? Experimental group? Control group? Experimental design (2:39)
Conditions Results
3 sealed jars No maggots on the meat
3 open jars Maggots on the meat
3 jars covered with fine net
No maggots on the meat
Where did the maggots come from?What was the purpose of the open jars?What was the manipulated variable?
•1668: Francesco Redi (biogenesis) placed decaying meat in nine jars then made these observations:
Conditions Results
Nutrient broth boiled, poured into flasks, and then sealed
Microbial growth
Where did the microbes come from?What error did he make?
•1745: John Needham (spon gen) put boiled nutrient broth into flasks.
Conditions Results
Nutrient broth placed in flask, sealed, then boiled
No microbial growth
Needham claims, “The ‘vital force’ was destroyed!”
•1767: Lazzaro Spallanzani (biogenesis) boiled nutrient solutions in sealed flasks.
Conditions Results
Nutrient broth placed in flask, boiled, not sealed
Microbial growth
Nutrient broth placed in flask, sealed, then boiled
No microbial growth
Why the difference?
•1861: Louis Pasteur (biogenesis) demonstrated that microorganisms are present in the air.
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: MicroscopyHistory 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 nmGreat 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 nmGreat for examining surface features
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
Individual silicon atoms
From the simple….(couple of thousand $$)
to the complex! (hundreds of thousands)