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bio chapter 11 2


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early earth
- Scientists think 5 billion years ago the solar system was forming
- They think the earth was forming 4.5 billion years ago
A. They think they early Earth was very unstable
- Hot volcanic activity, many chemical changes
how old stuff is
B. Oceans were forming about 3,9 billion years ago
C. The oldest rock ever found is 3.9 billion years old
D. The oldest fossil is 3.5 billion years old
E. The origin of life- 2 main explanations
- 1. Divine creation- life was created by Good or several Gods
- Different cultures have different divine explanations
- Divine creation is not a hypothesis that can be tested scientifically
- 2. Spontaneous Origin- Life developed through natural chemical and physical changes
F. Early scientists believed in spontaneous generation
- they thought living organisms could be created from none living organisms Fish made from mud, turtles made from rocks
- Major error- why believe?- lack of proper scientific observations and research
- Redi’s Experiment- Italian scientists, 1600s
- Studied flies and maggots
- Conclusion- maggots come from eggs laid by other flies
G. Spallanzani
- Italian scientists- 1700s
- He thought microbes formed from other microbes- not the air
- Other scientists said they were made from the air
H. Pastur-
- French scientists 1800s
- Expanded Spanllanzani;s ideas and destroyed the spontaneous generation theory
I. 4 developments Life to develop
- 1. formation of simple organic compounds- organic compounds or carbon are necessary for life- early earth contained CHON
- formation of complex organisms
- 3. Concentration and enclosure of organic compounds
- Oparin’s theory
scientist 1923- Primitive atmosphere contained ammonia, methane Ammonia, methane, hydrogen,
- Heat and these substances combined to form amino acids which are organic compounds
- Stanly Millar
- American scientist- 1953
- Used Oparins ideas
- Goes in a chamber- heat- electricity
- Within days- he created amino acids
- This Is The Primordial Soup Model
- Proteins are chains of amino acids that link
- Scientists have done this in lab
Micro sphere
a round shape and forms only one type of molecule
- The key is that DNA must be separated from the rest of the cell by some kind of boundaries

A. This process has also been done in lab
- 4. The Evolution of growth, metabolism, and replication
A. Coacervatis can’t grow metabolism and reproduce but over time might have developed those abilities
The Bubble Model
- 1986 Louis Lermn- stated the key chemical event took place in the bubbles at the ocean’s surface
A. This would speed up the process of creating life
B. It would protect the amino acids from the destruction by the ultra violent light of sun
The origins of Heredity
A. Still a mystery
B. Scientists think that RNA was the first information storing molecule to form
C. They think that the RNA enzymes catalyzed the assembly of the earliest proteins
D. But they don’t know for sure
Dating Fossils
Layering Method
- Earliest technique
- Not very accurate
- Based on sedimentation
Layering Method
Potassium Argon Method
- KA
- For fossils over 50,000 years old
- All rock contains potassium
- Part of potassium is K40 or potassium 40
- K40- unstable isotope
- K 40 breaks down at a known rate into A40
- The more A40- the older the rock
Dating Fossils
Carbon 14 Method
- good for fossils under 50,00 years old
- You need once living matter
- Living organisms contain a known amount of Carbon14 and carbon12
- After death the C14 breaks down at a known speed into N14
- They use a complex math equation to form the age of that fossil
- ½ life of C14 is 5,700 years
- ½ life- the time it takes for ½ of the element to decay or change into something else
Extraterrestrial Life
- Not proven- yet
- For life as we know it- conditions must be at a very marrow range of possibilities
- Scientists do believe life exists on other planets
- Live does not need DNA- only a way to preserve and pass on information to next generation
- If other life isn’t based on Carbon (as we are)- probably based on silicon and ammonia
A. 1960-beagn- Frank Drake – Search for extraterrestrial intelligence
B. 1992 NASA increased SETI efforts
C. 25 unusual signals found in first year
D. 1993- Congress cut the SETI program- “Lack of funds”

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