Download Theory =

History of life notes
Theory =
Early Earth
4.6 bya
- VERY (colliding meteorites, erupting volcanoes)
- Atmosphere was mostly nitrogen, carbon dioxide, water vapor, methane,
ammonia but _____________________________!!!
4.4 bya
- Earth ____________
- water vapor condenses into ________ creates oceans (where the first life will form)
Evidence that we do have!
Fossils =
(Examples:
A person who studies fossils is called a__________________ (just like Ross on Friends!)
How is a fossil made?
- after an organism is buried, the sand and clay around it harden to
form_________________________. Then erosion brings the fossil to the surface
Dating Fossils
1. Relative Dating- older rocks/fossils are on the ________ younger ones are on top
2. Absolute Dating (also called radiometric dating)- measures the amount of
___________ substance left in the rock or organism and determines its actual age
By examining rock layers and dating the fossils, scientists have been able to put together
a chronology, or calendar of Earth’s history called the____________________________.
(see left page)
Origin of Life
Cell Theory
1. all living things are made of ________
2. cells are basic unit of _______________ & ________________
3. All cells come from pre-existing cells.
What is the big question this theory raises?
1.
2.
- The initial belief was that life was created through _______________________
(abiogenesis).
Example:
Summary
History of life notes
Disproving Spontaneous Generation
1.
Francesco Redi was the first to disprove spontaneous generation in the 1600s.
Although Redi was able to disprove that large organisms did not simply appear,
many scientists thought that microorganisms (bacteria) were so numerous and
widespread that they must arise spontaneously- probably from a vital force in the air.
2. Louis Pasteur in the mid 1800’s designed an experiment that disproved the
spontaneous generation of_____________________________.
From this time on________________________ , the idea life comes from life holds true.
(Ex. Humans give birth to humans, mice to mice, etc.)
Summary
History of life notes
But…. How did the very first life form that start this chain reaction?!!!
The current theory is that life began in the_____________________.
Oparin’s hypothesis: Energy from the _______________________________________
triggered chemical reactions with the vapors that were present in the early atmosphere to
produce__________________________________________ . Then, the rain washed the
molecules into the _____________ to create what is called the _____________________
(place of the origin of life).
PROOF??
1953- Stanley Miller and Harold Urey tested the hypothesis by simulating the conditions
of early Earth in a lab.
Simple Molecules to Complex molecules?
- experiments were done to prove that simple molecules like
____________________ when heated without oxygen link up to
form_________________ (complex molecules)
Complex Molecules to Cells?
- Sidney Fox showed how amino acid chains will form _____________________
Evolution of Cells
1st cells =
2nd cells =
3rd cells =
Summary
History of life notes
First organisms were prokaryotes
2 types
– Archaebacteria – bacteria that live in ____________________, and more
closely related to early prokaryotes
– EubacteriaEndosymbiotic theory
Pre-eukaryotic bacteria engulfed another
– (similar to mitochondria or chloroplast)
Eukaryotic organisms formed much __________________ than prokaryotes
Summary