There are several hypotheses about the natural origin of life on Earth, each with supporting scientific evidence

 j-zk&feature=fvwrel j-zk&feature=fvwrel  j-zk&feature=fvwrel j-zk&feature=fvwrel

 Organic compounds on early Earth  Extraterrestrial sources  Abiotic synthesis of polymers  Protobionts  4Y 4Y  ktY ktY  pDg pDg

 Biotic  Abiotic  Polymers  Monomers  Protobionts

◦ Stromatolites  Endosymbiosis - next three slides  Genetic chimera

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Plasma membrane Infolding of the plasma membrane Nucleus Plasma membrane Endoplasmic reticulum (ER) Nuclear envelope Eukaryotic cell Prokaryotic ancestor of eukaryotic cells Prokaryotic cell DNA

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Eukaryotic cell with mitochondrion Chloroplast Endosymbiosis Photosynthetic bacterium Mitochondrion Internal membrane system Eukaryotic cell with chloroplast and mitochondrion Aerobic bacterium Ancestral eukaryotic cell

Fig Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Eukaryotic cell Nucleus Red algal nucleus lost Cyanobacteria Red alga Eukaryotic cell Brown alga Nucleus Secondary Endosymbiosis Primary Endosymbiosis Chloroplast with two membranes Organelle with four membranes

 CONJUGATION

 Oldest fossils of multicellular eukaryotes 1.2 – 1.5 billion years  1 st eukaryotes were colonized special cells  Cambrian Explosion  Colonization of land by fungi, plants, & animals  Drifting continents separated organisms, furthered evolution

Benchmark a, 5 parts See Unit Organization Handout  Essential knowledge 1.D.1