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

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

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

MILLER & UREY’S EXPERIMENT https://highered.mheducation.com/sites/9834092339/student_view0/chapter26/animation_-_miller-urey_experiment.html

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…

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!

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

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

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!

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

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.

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

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! https://highered.mheducation.com/sites/9834092339/student_view0/chapter4/animation_-_endosymbiosis.html

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 1.4-1.6 BYA, THE FIRST EUKARYOTIC CELLS APPEAR. THEY HAD A NUCLEUS THAT CONTAINED DNA SEXUAL REPRODUCTION occurred in EUKARYOTES which created Genetic Diversity