Download Origin of Life

Age of Earth:
BIO chapter 12
Earth’s Age:
• 4.6 Billion years
• Measured age of rocks
• Radiometric dating-using isotopes and half-life
that produce radiation and energy
Chemicals:
• Basic building blocks of life-CHO
• Is thought by some that organic molecules
have formed from non-living molecules
Three Life beginning models:
1. Primordial soup model-organic molecules formed
spontaneously with added energy- water and sunlight
**scientists today still disagree on origin of life
Life beginning models:
2. Miller-Urey model-atmospheric material
could make organic compounds-no ozone
problem-water and electricity
Life beginning models:
3. Bubble model-cycle of gases forming in ocean
water releasing chemicals into the
atmosphere- water and volcanoes
Microspheres:
• A. A. formed in tiny droplets
• 1st step toward cellular organization
• Thought that RNA formed from DNA
First Life froms
• Thought to appear 2.5 billion years ago
Sequence of formation:
• anthropods-vertebrates-fish-amphibians-reptiles-birds-mammals
Extinction:
• 5 periods of extinction on Earth so far
• Extinction-one species dies out
• Mass extinction-many species die