1. ORIGINS OF LIFE ON EARTH
CHAPO
BIOLOGY 1 HONORS

2. DIN –When did life begin on Earth? Explain your answer.
ORIGINS OF LIFE ON EARTH
DIN –When did life begin on Earth? Explain your answer.

3. What was the Earth like when it was formed?
Conditions on Earth were HOT and VIOLENT!
Meteorites, asteroids and comets colliding with the Earth’s surface
Oxygen was not abundant like it is today
Ammonia, methane, water vapor and carbon dioxide made up the atmosphere

4. The cooling of WATER VAPOR = LIQUID RAIN = THE FIRST BODIES OF WATER!
Collisions became less frequent and the Earth began to cool
The cooling of WATER VAPOR = LIQUID RAIN = THE FIRST BODIES OF WATER!
Once liquid water was formed, organic compounds could be made

5. Organic Molecule Hypothesis (2)
Miller – Urey Experiment
- lightning was passed through the early gasses of the atmosphere made organic molecules

6. Organic Molecule Hypothesis (2)
Meteorite Hypothesis
*organic molecules can be found in space

7. How did the earliest cells form?
IRON-SULFIDE BUBBLES HYPOTHESIS
- deep sea vents = hot iron- sulfide meets cool ocean water.
released early microbes

8. How did the earliest cells form?
2. Lipid Membrane Hypothesis
Liposomes form around organic compounds, separating them from the environment.

9. But, how did early cells have genetic material?
RNA may have come before DNA
RNA can copy itself, cut itself and replicate itself, unlike DNA.
Because DNA stores genetic information better, RNA may have become less important for these functions.

10. What were the earliest cells?
Photosynthetic life evolved more than 3.5 billion years ago
CYANOBACTERIA = one of the earliest organisms on Earth!
Anaerobic organisms began releasing oxygen
Allowed for aerobic processes! (like us!)

11. What do we already know about early cells…..
The first cells were simple, prokaryotic cells
They had no organelles
They only had very simple RNA codes
They were anaerobic, living without oxygen
They reproduced asexually

12. So how did EUKARYOTIC cells form?
ENDOSYMBIOSIS = one organism lives in the body of another and both benefit!
Created early mitochondria and chloroplast