Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 25 The History of Life on Earth

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 25.1: Conditions on early Earth made the origin of life possible Chemical & physical processes on early Earth may have produced very simple cells through: 1. Abiotic synthesis of small organic molecules 2. Joining of these small molecules into macromolecules 3. Packaging of molecules into “protobionts” 4. Origin of self-replicating molecules

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Synthesis of Organic Compounds on Early Earth Earth formed about 4.6 billion years ago, along with the rest of the solar system Earth’s early atmosphere likely contained water vapor and chemicals released by volcanic eruptions (nitrogen, nitrogen oxides, carbon dioxide, methane, ammonia, hydrogen, hydrogen sulfide)

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Miller and Urey conducted experiments that showed that the abiotic synthesis of organic molecules in a reducing atmosphere is possible

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings However, the evidence is not yet convincing that the early atmosphere was in fact reducing Instead of forming in the atmosphere, the first organic compounds may have been synthesized near submerged volcanoes and deep-sea vents Video: Hydrothermal Vent Video: Hydrothermal Vent Video: Tubeworms Video: Tubeworms

Fig. 25-2

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Amino acids have also been found in meteorites

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Protobionts Replication and metabolism are key properties of life Protobionts are aggregates of abiotically produced molecules surrounded by a membrane or membrane-like structure Protobionts exhibit simple reproduction and metabolism and maintain an internal chemical environment

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Self-Replicating RNA and the Dawn of Natural Selection The first genetic material was probably RNA, not DNA RNA molecules called ribozymes have been found to catalyze many different reactions – For example, ribozymes can make complementary copies of short stretches of their own sequence or other short pieces of RNA

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Early protobionts with self-replicating, catalytic RNA would have been more effective at using resources and would have increased in number through natural selection The early genetic material might have formed an “RNA world”

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Concept 25.2: The fossil record documents the history of life The fossil record reveals changes in the history of life on earth

Fig Present Dimetrodon Coccosteus cuspidatus Fossilized stromatolite Stromatolites Tappania, a unicellular eukaryote Dickinsonia costata Hallucigenia Casts of ammonites Rhomaleosaurus victor, a plesiosaur 100 million years ago ,500 1, cm 4.5 cm 1 cm

Fig Fossilized stromatolite Stromatolites Tappania, a unicellular eukaryote Dickinsonia costata Hallucigenia ,500 1, cm 4.5 cm 1 cm

Fig. 25-4a-2 Present Dimetrodon Coccosteus cuspidatus Casts of ammonites Rhomaleosaurus victor, a plesiosaur 100 million years ago cm

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Few individuals have fossilized, and even fewer have been discovered The fossil record is biased in favor of species that – Existed for a long time – Were abundant and widespread – Had hard parts Animation: The Geologic Record Animation: The Geologic Record

Table 25-1

Table 25-1a

Table 25-1b

Fig Animals Colonization of land Paleozoic Meso- zoic Humans Ceno- zoic Origin of solar system and Earth Prokaryotes Proterozoic Archaean Billions of years ago Multicellular eukaryotes Single-celled eukaryotes Atmospheric oxygen

Fig 25-UN2 Prokaryotes Billions of years ago Stromatolites- layered rocks; form when prokaryotes bind sediment together

Fig 25-UN3 Atmospheric oxygen Billions of years ago Banded iron formation (red streaks are iron oxide) 2.7 bya

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Photosynthesis and the Oxygen Revolution Most atmospheric oxygen (O 2 ) is of biological origin O 2 produced by photosynthesis reacted with dissolved iron and precipitated out to form banded iron formations The source of O 2 was likely bacteria similar to modern cyanobacteria

Fig 25-UN4 Single- celled eukaryotes Billions of years ago

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The First Eukaryotes The oldest fossils of eukaryotic cells date back 2.1 billion years Endosymbiosis proposes that mitochondria and plastids (chloroplasts and related organelles) were formerly small prokaryotes living within larger host cells An endosymbiont is a cell that lives within a host cell

Fig Aerobic heterotrophic prokaryote Mitochondrion Ancestral heterotrophic eukaryote

Fig Ancestral photosynthetic eukaryote Photosynthetic prokaryote Mitochondrion Plastid

Fig Ancestral photosynthetic eukaryote Photosynthetic prokaryote Mitochondrion Plastid Nucleus Cytoplasm DNA Plasma membrane Endoplasmic reticulum Nuclear envelope Ancestral prokaryote Aerobic heterotrophic prokaryote Mitochondrion Ancestral heterotrophic eukaryote

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Evidence supporting endosymbiosis: – Inner membranes of mitochondria and plastids homologous to those in prokaryotic cell membranes – Replication is similar in these organelles and prokaryotes – Organelles contain a singular, circular DNA molecule – These organelles transcribe and translate their own DNA – Their ribosomes are more similar to prokaryotic than eukaryotic ribosomes

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Answers must be in essay form. Outline form is not acceptable. Labeled diagrams may be used to supplement discussion, but in no case will a diagram alone suffice. It is important that you read each question completely before you begin to write. 1. During an investigation of a freshwater lake, an AP Biology student discovers a previously unknown microscopic organism. Further study shows that the unicellular organism is eukaryotic. (a) Identify FOUR organelles that should be present in the eukaryotic organism and describe the function of each organelle. (b) Prokaryotic cells lack membrane-bound organelles found in eukaryotes. However, prokaryotes must perform many of the same functions as eukaryotes. For THREE of the organelles identified in part (a), explain how prokaryotic cells carry out the associated functions. (c) According to the endosymbiotic theory, some organelles are believed to have evolved through a symbiotic relationship between eukaryotic and prokaryotic cells. Describe THREE observations that support the endosymbiotic theory.

Fig 25-UN5 Multicellular eukaryotes Billions of years ago

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Origin of Multicellularity The evolution of eukaryotic cells allowed for a greater range of unicellular forms A second wave of diversification occurred when multicellularity evolved and gave rise to algae, plants, fungi, and animals

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Earliest Multicellular Eukaryotes Comparisons of DNA sequences date the common ancestor of multicellular eukaryotes to 1.5 billion years ago The oldest known fossils of multicellular eukaryotes are of small algae that lived about 1.2 billion years ago Volvox – colonial algae

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Cambrian Explosion Cambrian explosion – the sudden appearance of fossils resembling modern phyla in the Cambrian period (535 to 525 mya) The Cambrian explosion provides the first evidence of predator-prey interactions hQ&feature=related

Fig 25-UN6 Animals Billions of years ago DNA suggests that animals diverged before the Cambrian explosion, perhaps as early as 700 million to 1 bya

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The Colonization of Land Fungi, plants, and animals began to colonize land about 500 mya Plants & fungi likely colonized land by 420 mya Arthropods & tetrapods are the most widespread and diverse land animals Tetrapods evolved from lobe-finned fishes around 365 million years ago

Fig 25-UN7 Colonization of land Billions of years ago

Fig South America Pangaea Millions of years ago Mesozoic 251 Paleozoic Gondwana Laurasia Eurasia India Africa Antarctica Australia North America Madagascar Cenozoic Present The land masses of Earth have formed a supercontinent: 1.1 billion, 600 million, and 250 million years ago

Fig b Pangaea Millions of years ago 135 Mesozoic 251 Paleozoic Gondwana Laurasia Break-up of Pangaea lead to allopatric speciation Distribution of fossils supports continental drift For example, the similarity of fossils in South America and Africa is consistent with the idea that these continents were formerly attached

Fig a South America Millions of years ago 65.5 Eurasia India Africa Antarctica Australia North America Madagascar Cenozoic Present

Fig (a) Cutaway view of Earth (b) Major continental plates Inner core Outer core Crust Mantle Pacific Plate Nazca Plate Juan de Fuca Plate Cocos Plate Caribbean Plate Arabian Plate African Plate Scotia Plate North American Plate South American Plate Antarctic Plate Australian Plate Philippine Plate Indian Plate Eurasian Plate

Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings The history of life on Earth has seen the rise and fall of many groups of organisms Concept 25.4: The rise and fall of dominant groups reflect continental drift, mass extinctions, and adaptive radiations Video: Lava Flow Video: Lava Flow Video: Volcanic Eruption Video: Volcanic Eruption

Fig Total extinction rate (families per million years): Time (millions of years ago) Number of families: Cenozoic Mesozoic Paleozoic E OS D C P Tr J Era Period 5 C P N

Fig NORTH AMERICA Chicxulub crater Yucatán Peninsula

Fig 25-UN8 Millions of years ago (mya) 1.2 bya: First multicellular eukaryotes 2.1 bya: First eukaryotes (single-celled) 3.5 billion years ago (bya): First prokaryotes (single-celled) 535–525 mya: Cambrian explosion (great increase in diversity of animal forms) 500 mya: Colonization of land by fungi, plants and animals Present 500 2,000 1,500 1,000 3,000 2,500 3,500 4,000

Fig 25-UN11 Origin of solar system and Earth Paleozoic Meso- zoic Ceno- zoic Proterozoic Archaean Billions of years ago