Origin of life

Abiotic

Not able to sustain life

Describe the timeline of early earth

1. Giant impact - Earth was a hot mass of molten rock

2. Abel bombardment where Hadean Earth was bombarded with asteroids

3. Formation of atmosphere where chemically rich oceans were formed from water condensation

Why were Earth’s first organisms able to live in high temperatures?

Atmosphere MOSTLY consisted of greenhouse gases

Why has the Earth’s atmospheric carbon reduced significantly?

Plants and other living organisms photosynthesize and produce oxygen and capture carbon

• Most carbon now exists as minerals

List the four steps to life on Earth

1. Synthesis of organic molecules

2. Polymerization

3. Formation of protocells

4. Self replication

Synthesis of organic molecules

Abiotic synthesis of monomers like amino acids and nitrogenous bases

Oparin Haldene hypothesis

Old Earth conditions facilitated synthesis of monomers

• Oceans = chemical cooking pot

• Anaerobic/reducing atmosphere

• Presence of energy = lightning or UV rays

Milller and Urey

Tested the Oparin haldene hypothesis and were successful in recreating Earth’s atmosphere to demonstrate the synthesis of organic molecules

Polymerization

The organization of monomers into polymers (protein, nucleic acid, polysaccharides)

What is required for polymerization?

1. Energy sources to drive non spontaneous reactions

2. Enzymes to act as a catalyst

Protocells

Simple, rudimentary, membrane bound compartments that allow in and out movements (metabolism) .They change and grow, split into daughter cells, and incorporate external materials

Self replicating molecules (genetic polymers)

• First genetic material was RNA

  • Stores genetic information

  • Self replicating WITHOUT enzymes

What are characteristics of ALL present day cells?

1. Boundary (membrane) separating interior and exterior

2. 1st nucleic acid molecules

3. System using information coded in nucleic acids to make proteins and other molecules

4. Metabolic system to provide energy

Why is abiotic synthesis NOT POSSIBLE today

1. Free oxygen would destroy intermediate products

2. Reducing atmosphere is NOT present

3. Life comes from PREEXISTING LIFE