1. FIRST SIGNS OF LIFE ON EARTH
HOW DID LIFE ON EARTH FIRST ARISE?
EARTH IS 4.6 BYO
IT AROSE FROM GASES & DUST FROM SPACE THAT CONDENSED
GRAVITY PULLED THE MATTER TIGHTER TOGETHER, HEAT FROM PRESSURE & RADIATION, MELTED MOST OF THE MATTER
THE FIRST SOLID ROCKS DATE FROM 4 BYO
THERE WAS LOTS OF VOLCANIC ACTIVITY ON EARTH
METEORS BOMBARDED THE EARTH

2. FIRST SIGNS OF LIFE ON EARTH THE EARLY ATMOSPHERE
THERE WAS NO ATMOSPHERE ON EARTH
SO WHERE DID IT COME FROM?
1. VOLCANIC GASES –CH4, CO2, N, NH3
THERE WAS LITTLE OR NO O2!
2. THERE WAS H2O VAPOR
THE WATER COLLECTED ON THE EARTH’S CRUST AND PICKED UP MINERALS, SALTS AND GASES AND CREATED OCEANS.
3. THERE WAS NO OZONE LAYER, SO Ultra Violet RAYS REACHED THE EARTH’S SURFACE
LIGHTNING STORMS PRODUCED ELECTRICAL ENERGY

3. FIRST SIGNS OF LIFE ON EARTH LIFE BEGINS
THESE CONDITIONS ON EARTH SET THE STAGE FOR LIFE TO BEGIN
WHAT ELEMENTS DO YOU NEED TO CREATE ORGANIC COMPOUNDS?
H, C, O, S AND N
WHAT ENERGY SOURCES WERE AVAILABLE ON THE EARLY EARTH?
SUNLIGHT AND LIGHTNING

4. MILLER & UREY’S EXPERIMENT

5. MILLER & UREY 1953
THEY CREATED AN EXPERIMENT TO SIMULATE EARLY EARTH’S ENVIRONMENT
1.THEY PUT H2O VAPOR, METHANE, AMMONIA & H GAS INTO A CHAMBER TO REPRESENT THE EARLY ATMOSPHERE.
2. ELECTRODES AND THE BUNSEN BURNER GENERATED ENERGY AS THE LIGHTNING, Volcanoes AND SUN WOULD HAVE
AFTER A WEEK THEY EXAMINED THE CHAMBER AND FOUND…

6. MILLER & UREY’S RESULTS
The ingredients for LIFE!
Their experiment contained AMINO ACIDS, & other organic compounds
In addition to water, METEORITES may have been the source for IMPORTANT COMPOUNDS in the OCEAN, like minerals and elements
DNA & RNA NITROGEN BASES have been found inside of METEORITES!

7. PROTO-CELLS POLYMERS
SOME SCIENTISTS THEORIZE THAT THE FIRST POLYMERS FORMED BY SEA WATER PUDDLES DRYING UP.
THIS LEFT CONCENTRATED MOLECULES CLOSE ENOUGH TO JOIN

8. PROTO-CELLS MEMBRANES
FORMATION OF A MEMBRANE IS ESSENTIAL TO PROTECT THE MOLECULES
WHEN PROTEINS & H2O MIX THEY FORM A BUBBLE-LIKE STRUCTURE- Coacervates
THEY BEHAVE LIKE
CELL MEMBRANES

9. PROTO-CELLS HEREDITY & REPLICATION
The first genetic material may have been RNA , WHY?
SINGLE STRAND, SIMPLER MOLECULE
IN LAB EXPERIMENTS -RNA IS MIXED IN A TEST TUBE W/ FREE RNA NUCLEOTIDES, SEGMENTS OF COMPLEMENTARY RNA ARE MADE
LIFE WOULD HAVE BEGUN!

10. Prokaryotes Evolve
At some point a form of photosynthesis evolved. These Prokaryotes probably used H2S instead of H2O. Why?
They were Extremophiles!
They lived in harsh conditions near deep sea vents that emitted toxic chemicals
These autotrophes
Can create their own food from chemicals
were common 3.0 Billion years ago
They grew in matt-like layers in the ocean. They were called Stromatolites blue green algae

11. The First True, Living Cells
They were PROKARYOTES –probably looked like Bacteria
HETEROTROPHIC
they could not make their own food
they got energy from ingesting molecules around them, like, Methane gas, hydrogen sulfide gas
They lived in the ocean near vents of volcanic activity
They were ANAEROBES
did not use Oxygen WHY?
There was no O2 yet in the Atmosphere!
They reproduced ASEXUALLY. This is like creating a clone. There is no genetic diversity unless a mutation occurs.

12. STROMATOLITES THE 1ST AUTOTROPHS These are off the coast of Australia

13. SO IF O2 IS DEADLY TO ANAEROBES…
WHY ARE THEY STILL HERE?
How did they survive when the oxygen started to accumulate on Earth?
Where did they go to escape from the oxygen?
Some live in deep mud and soil and some went inside of other cells. This is called the Endosymbiotic Theory. Check out your worksheet!

14. FORMATION OF AN OZONE, 1ST EUKARYOTES, SEXUAL REPRODUCTION
When Photosynthesis started to occur on Earth the O2 that was given off from the PROKARYOTES reached the STRATOSPHERE (layer of the atmosphere) & formed the ___________OZONE LAYER (O3)
IT FILTERS U.V. RAYS THAT REACH THE EARTH
FILTERING OF THE OZONE ALLOWED OTHER LIFE FORMS TO EVOLVE SINCE THE U.V. RAYS WERE NOT AS STRONG
BYA, THE FIRST EUKARYOTIC CELLS APPEAR. THEY HAD A NUCLEUS THAT CONTAINED DNA
SEXUAL REPRODUCTION occurred in EUKARYOTES which created Genetic Diversity