History of Life on Earth

exam 3

origin of the solar system

particles + gas rushing inward = spinning

happened through accretion

Accretion

collection of mass accumulating more and more over time as it spins around the center

Formation of the Earth

4.6 Billion years ago

happened through accretion, but differentiated by density (core is densest → mantle→ crust)

had to have been molten at the beginning for materials to flow through one another

Earth - goldilocks zone

Habitable temperature and distance from the sentence - liquid water can exist

Large meteoroid crashes into earth → spewed materials out → moon + tilt of the earth

Moon and tilt of the earth (gravitational pull) gave us the tides and seasons

primordial soup theory

the early ocean was a large collection of organic molecules and little energy

little energy and organic molecules react to make more complex molecules

primordial sandwich theory

reactions rates in a vat of water alone are not good

water with a substrate (clay or ash) had much better reaction rates

increased better reaction rates would lead to more complex molecules (splashing of oceans and the tides)

Miller + Urey

Experiment that gave 4 complex molecules from basic elements and some energy

(chamber - understanding of atmosphere on early earth) used silicate glass because silica was present on early earth and important to the evolution of life

(boil liquid - heat up environment)

(cooling system allowed for condensation)

(spark - energy)

Protocells

enclosed vesicles made of lipid membranes - don’t evolve and are not quite living

RNA World Hypothesis

Believed RNA was the first genetic molecule on earth

Because - RNA can self replicate and acts as an enzyme to facilitate other reactions under early earth’s conditions

Peptide-RNA word hypothesis

believed RNA would have needed replication assistance from some kind of protein like a basic version of tRNA synthetase

Characteristics of Life

reproduction, energy use, homeostasis, response to environment, growth/development, organization/emergent properties, evolve/adapt