1. Evolution-Change Through Time
5-1
Evolution-Change Through Time
3/27/14

2. Abiogenesis vs. Biogenesis
Pasteur and Redi
Biogenesis: life comes from life
Abiogenesis-life comes from nonliving things
spontaneous generation
Old ideas:
Decaying meat creates maggots
Mudfish
Grainmice

3. 1885 Rabies Vaccine 1st human test administered on July 6
9 year old Joseph Meister
JOSEPH MEISTER LIVED

4. Early Atmosphere H2O vapor, methane (CH4), ammonia (NH3), H2
As earth cooled, H2O condensed and fell as rain, creating the ocean
As the rain fell, it carried these atmospheric gases into the ocean
Earth was an energy-rich environment
Hot, lightning, X rays & UV rays from the sun, radioactivity from rocks

5. Early Atmosphere-Continued
Energy was the driving force for synthesis reactions
Inorganic raw materials in the seas became chemically bonded to form organic molecules (simple sugars and amino acids; become the building blocks of the first life forms)
Simple organic molecules formed more complex organic molecules (aggregates) through synthesis reactions

6. The HETEROTROPH HYPOTHESIS
Aggregates absorbed simple organic molecules for “food”; therefore, these aggregates were considered heterotrophs
Early heterotrophs carried out anaerobic respiration (fermentation) (NO O2 yet)
This introduced CO2 into the atmosphere
Eventually some heterotrophs developed the ability to use CO2 to synthesize organic compounds
These were the first autotrophs…which would release O2 into the air

7. Early Atmosphere-Continued
Autotrophic activity(photosynthesis) added free O2 to the atmosphere
Over time, the capacity to use free O2 in respiration (aerobic respiration) evolved in both autotrophs and heterotrophs.
On modern earth, autotrophs and heterotrophs both still exist.
Some carry on anaerobic respiration but in most, respiration is aerobic

8. Miller and Urey
Tried to explain how the organic molecules that are found in all organisms are formed
In 1953, Miller and Urey found that, over a few days, a closed system of gases (CH4, NH3, H2O vapor, and H2) produced all 20 amino acids, sugars, lipids, and nitrogen bases in nucleic acids

10. Miller and Urey-Continued
Experiment called into questioned because the atmospheric conditions were not the same as those of the early earth.
Article was reprinted in 1979 with a retraction stating that it was unlikely life could have started by chance given the amount of time as previously proposed following the results of this experiment

11. Earth Formation Big Bang Theory 4.6 billion years ago
High temp. = no liquid water
Meteorites impacts
Volcanic eruptions
No ozone layer to block UV radiation
Cooling of the Earth
~ billion years ago first life began in the ancient ocean.

12. Proof? There is no direct evidence of early Earth
Physical evidence of early life has been found
Fossils- the remains of past life
most often
found in
sedimentary
rock

14. How old is a fossil?
Relative dating
Radiometric dating

15. Relative Dating: Using Rock Layers to Date Fossils1 A
Youngest layer 2
A B 3
A B C 4
B C 5
C D
Oldest layer
Which species appeared 1st?
Which species was around the longest?
Which species appeared most recently?

18. Endosymbiont Theory Aerobic Bacteria cyanobacteria
Communities of prokaryotes formed eukaryotes
Aerobic Bacteria
cyanobacteria
Prokaryote “eats” bacteria
Prokaryote
Bacteria become
mitochondria
Bacteria become
chloroplasts

19. Endosymbiotic Theory
4/13/2019

20. Time Frames for Evolution
1. Punctuated Equilibrium
-Species have long periods
of stability (millions of years),
Interrupted by brief periods
of major changes.
2. Gradualism
Evolutionary change occurs slowly, gradually, and continuously.

21. Biological Timeline

22. Show 60 minutes episode
“Killing Cancer” (Biotech notes)
4/13/2019