Chapter 26 Early Earth and the Origin of Life. Major events in earth’s history:

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:

3.5 billion years ago

Earliest fossil prokaryotes

Major events in earth’s history:

2.7 billion years ago

Oxygen accumulates in atmosphere

Major events in earth’s history:

2.7 billion years ago

Oxygen accumulates in atmosphereCyanobacteria evolve oxidative photosynthesis

Major events in earth’s history:

2.1 billion years ago

First eukaryotic cells

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:

1.Abiotic (nonliving) synthesis of small organic molecules

2.Joining these monomers into polymers

3.Origin of self-replicating molecules

4.Packaging into “probionts” (droplets with membranes).

The origin of life:

1.Abiotic (nonliving) synthesis of small organic molecules

2.Joining these monomers into polymers

The Miller-Urey experiment.

The origin of life:

3. Origin of self-replicating molecules.

The origin of life:

4.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

Monara

Protista

Plantae

Fungi

Animalia

Domains Kingdoms

Archaea

Bacteria

Eukarya

Monera

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

.