ORIGINS OF LIFE ON EARTH CHAPO BIOLOGY 1 HONORS

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.

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

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

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

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

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

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

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.

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!)

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

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