Bellwork Between molecules and prokaryotic cells we had

Bellwork • Between molecules and prokaryotic cells, we had ______s. • In these, what was probably the first genetic material?

Oo. L AP Bio

1 - Early Earth conditions (atmosphere, energy, etc) 2 - Origin of macromolecules (think Miller-Urey experiment) 3 - Protobionts 4 - RNA World hypothesis 5 - The first life forms 6 - The origin of photosynthesis and the "oxygen revolution" 7 - The origin of eukaryotes and endosymbiosis 8 - The origin of sexual reproduction and multicellularity 9 - The "Cambrian explosion" 10 - The colonization of land

What it boils down to… like in a soup…a primordial soup. • Molecules • Protobionts (with RNA) • Prokaryotic cells • Photosynthesis • Endosymbiosis of mito eukaryotic cells • Later, endosymbiosis of chloroplasts plant lineage

What it boils down to… like in a soup…a primordial soup. • Molecules • Protobionts (with RNA) • Prokaryotic cells • Photosynthesis • Endosymbiosis of mito eukaryotic cells • Later, endosymbiosis of chloroplasts plant lineage

Molecular Evolution Miller-Urey experiment showed that complex organic molecules could have formed under early Earth conditions • Inorganics Small organics Complex organics (macromolecules)

What it boils down to… like in a soup…a primordial soup. • Molecules • Protobionts (with RNA) • Prokaryotic cells • Photosynthesis • Endosymbiosis of mito eukaryotic cells • Later, endosymbiosis of chloroplasts plant lineage

Protobionts • Bubble of membrane with different internal chemistry than environment • Can “reproduce” • Add genetic material (RNA) and metabolism, and it’s starting to look like a cell • Can be made in labs (in water)

What it boils down to… like in a soup…a primordial soup. • Molecules • Protobionts (with RNA) • Prokaryotic cells • Photosynthesis • Endosymbiosis of mito eukaryotic cells • Later, endosymbiosis of chloroplasts plant lineage

Prokaryotic Photosynthesis Prokaryotes do NOT have chloroplasts (no membranous organelles)

What it boils down to… like in a soup…a primordial soup. • Molecules • Protobionts (with RNA) • Prokaryotic cells • Photosynthesis • Endosymbiosis of mito eukaryotic cells • Later, endosymbiosis of chloroplasts plant lineage

Evidence: Mitochondria and chloroplasts… 1. Have membranes like prokaryotic membranes 2. Have ribosomes like prokaryotic ribosomes 3. Have chromosomes like prokaryotic chromosomes 4. Reproduce through binary fission (like prokaryotes)

Chloroplast Endosymbiosis explains differences among plant lineages

Assignment Draw a phylogeny for early organisms (include protobionts) Exit slip: Evaluate one hypothesis about Oo. L. Describe the hypothesis and state whether you agree or disagree, citing scientific evidence.