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© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor,

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Presentation on theme: "© 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor,"— Presentation transcript:

1 © 2012 Pearson Education, Inc. Lecture by Edward J. Zalisko PowerPoint Lectures for Campbell Biology: Concepts & Connections, Seventh Edition Reece, Taylor, Simon, and Dickey Chapter 15 Tracing Evolutionary History

2 MAJOR EVENTS IN THE HISTORY OF LIFE © 2012 Pearson Education, Inc.

3 Lifes Calendar

4 Figure 15.4 Archaean eon Proterozoic eon Phanerozoic eon Animals Multicellular eukaryotes Single-celled eukaryotes Atmospheric oxygen Billions of years ago Prokaryotes Present Origin of Earth Colonization of land

5 Prokaryotes lived alone on Earth for 1.5 billion years, from 3.5 to 2 billion years ago. –During this time, prokaryotes transformed the atmosphere. –Prokaryotic photosynthesis produced oxygen that enriched the water and atmosphere of Earth. –Anaerobic and aerobic cellular respiration allowed prokaryotes to flourish The origins of single-celled and multicelled organisms and the colonization of land were key events in lifes history © 2012 Pearson Education, Inc.

6 The oldest fossils of eukaryotes are about 2.1 billion years old. The common ancestor of all multicellular eukaryotes lived about 1.5 billion years ago. The oldest fossils of multicellular eukaryotes are about 1.2 billion years old. The first multicellular plants and fungi began to colonize land about 500 million years ago The origins of single-celled and multicelled organisms and the colonization of land were key events in lifes history © 2012 Pearson Education, Inc.

7 Humans diverged from other primates about 6 to 7 million years ago. Our species, Homo sapiens, originated about 195,000 years ago. If the Earths history were compressed into an hour, humans appeared less than 0.2 seconds ago! 15.4 The origins of single-celled and multicelled organisms and the colonization of land were key events in lifes history © 2012 Pearson Education, Inc.

8 Larger Cells and Organisms Need More Oxygen More O 2 allows for CR and aerobic metabolism = greater ATP yield!!

9 All living organisms share many biochemical and developmental pathways: DNA --> RNA --> Protein Same genetic code Transcription/translation/replication processes same Glycolysis and cellular respiration similar Many genes are amazingly similar –About 99% of the genes of humans and mice are homologous. –About 50% of human genes are homologous with those of yeast. Molecular Homologies Provide Greatest Evidence for Lifes Common Ancestor © 2012 Pearson Education, Inc.

10 Molecular homologies have unveiled a new organization to lifes history. Comparison of rRNA gene sequences by Carl Woese Remember, rRNA gene sequences allow for comparison of long-distance relationships Biologists currently recognize a three-domain system consisting of –two domains of prokaryotes: Bacteria and Archaea, and –one domain of eukaryotes called Eukarya including –fungi, protists, plants, animals Three Domain System © 2012 Pearson Education, Inc.

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12 Figure 15.19A Most recent common ancestor of all living things Gene transfer between mitochondrial ancestor and ancestor of eukaryotes Gene transfer between chloroplast ancestor and ancestor of green plants Bacteria Eukarya Archaea Billions of years ago

13 Figure 1.4 The Tree of Life

14 Bacteria and Archaea diverged very early in the evolutionary history of life Archaea are more closely related to eukaryotes than to bacteria. Eukarya diverged from line of Archaea Several endosymbiotic events lead to evolution of eukaryotes Mitochrondria acquired from aerobic bacteria Chloroplast from photosynthetic bacteria Mitochondria acquired first; 1st eukaryotes heterotrophic Multicellularity in eukaryotes arose multiple times (convergent evolution) Implications of Updated Tree of Life © 2012 Pearson Education, Inc.

15 Honors Biology Endosymbiosis theory Mitochondria & chloroplasts were once free living bacteria engulfed by ancestral eukaryote Endosymbiont cell that lives within another cell (host) as a partnership evolutionary advantage for both one supplies energy the other supplies raw materials & protection Lynn Margulis U of M, Amherst

16 Honors Biology Endosymbiosis theory Evolution of eukaryotes


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