Chapter 26 Early Earth and the Origin of Life

Major events in earth’s history:

Major events in earth’s history: 4.5 billion years ago Earth is formed

Major events in earth’s history: 3 Major events in earth’s history: 3.5 billion years ago Earliest fossil prokaryotes

Major events in earth’s history: 2 Major events in earth’s history: 2.7 billion years ago Oxygen accumulates in atmosphere

2.7 billion years ago Oxygen accumulates in atmosphere Major events in earth’s history: 2.7 billion years ago Oxygen accumulates in atmosphere Cyanobacteria evolve oxidative photosynthesis

Major events in earth’s history: 2 Major events in earth’s history: 2.1 billion years ago First eukaryotic cells

Major events in earth’s history: 1 Major events in earth’s history: 1.2 billion years ago First multicellular algae

Major events in earth’s history: 600 million years ago First animals

Major events in earth’s history: 540-520 million years ago “Cambrian explosion”

Major events in earth’s history: 500 million years ago Colonization of land

Major events in earth’s history:

The origin of life: Abiotic (nonliving) synthesis of small organic molecules Joining these monomers into polymers Origin of self-replicating molecules Packaging into “probionts” (droplets with membranes).

The origin of life: Abiotic (nonliving) synthesis of small organic molecules Joining these monomers into polymers The Miller-Urey experiment.

The origin of life: 3. Origin of self-replicating molecules.

The origin of life: Packaging into “probionts” (droplets with membranes).

Dumb kings play chess on fine green sand domain kingdom phylum class order family genus species eukaryote animal chordate mammal anthropoid primate homo sapiens

Domains Kingdoms Archaea Bacteria Eukarya Monara Protista Plantae Fungi Animalia

Domains Kingdoms Archaea Bacteria Eukarya Monera Protista Plantae Fungi Animalia

Prokaryotes Most have cell walls made of peptidoglycan Many have polysaccharide capsule Many have sticky fimbriae and pili About half move with flagella Some have specialized membranes DNA in one big loop plus plasmids.

Prokaryotes Photoautotrophs use sunlight Chemoautotrophs use inorganic fuels Heterotrophs consume carbon.

Oxygen Aerobe uses oxygen Anaerobe does not use oxygen Obligate aerobes cannot grow without O2 Obligate anaerobes are poisoned by O2 Facultative anaerobes use O2 when it’s available but can also do fermentation.

Nitrogen Prokaryotes are able to turn N2 into NH3 in a process called nitrogen fixation.

Archaeabacteria Analysis of rRNA shows that some bacteria are more closely related to eukaryotes and belong in a domain of their own. Extremophiles (thermophiles and halophiles) Methanogens.

Symbiosis Mutualism Commensalism Parasitism .