BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 16 The Origin and Evolution of Microbial Life: Prokaryotes and Protists

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Biological and geologic history are closely intertwined Fossilized mats of prokaryotes 2.5 billion years old mark a time when photosynthetic bacteria were producing O 2 that made the atmosphere aerobic –These fossilized mats are called stromatolites How Ancient Bacteria Changed the World

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Planet Earth formed some 4.6 billion years ago 16.1 Life began on a young Earth EARLY EARTH AND THE ORIGIN OF LIFE

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The early atmosphere probably contained H 2 O, CO, CO 2, N 2, and possibly some CH 4, but little or no O 2 Volcanic activity, lightning, and UV radiation were intense Figure 16.1A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Fossilized prokaryotes date back 3.5 billion years Figure 16.1B, D

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Life may have developed from nonliving materials as early as 3.9 billion years ago Figure 16.1C = 500 million years ago Earliest animals; diverse algae Earliest multicellular eukaryotes? Earliest eukaryotes Accumulation of atmospheric O 2 from photosynthetic cyanobacteria Oldest known prokaryotic fossils Origin of life? Formation of Earth Billions of years ago

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Small organic molecules must have appeared first –This probably happened when inorganic chemicals were energized by lightning or UV radiation 16.2 How did life originate?

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 16.3 Talking About Science: Stanley Miller’s experiments showed that organic materials could have arisen on a lifeless earth Figure 16.3A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Simulations of such conditions have produced amino acids, sugars, and nucleotide bases Figure 16.3B Water vapor CH 4 Electrode NH 3 H2H2 Condenser Cold water Cooled water containing organic compounds Sample for chemical analysis H2OH2O

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These molecules could have polymerized on hot rocks or clay –This could have produced polypeptides and short nucleic acids 16.4 The first polymers may have formed on hot rocks or clay

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The first genes may have been RNA molecules –These molecules could have catalyzed their own replication in a prebiotic RNA world 16.5 The first genetic material and enzymes may both have been RNA Figure 16.5 Monomers Formation of short RNA polymers: simple “genes” 1 Assembly of a complementary RNA chain, the first step in replication of the original “gene” 2

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These molecules might have acted as rough templates for the formation of polypeptides –These polypeptides may have in turn assisted RNA replication 16.6 Molecular cooperatives enclosed by membranes probably preceded the first real cells Figure 16.6A Self-replication of RNA RNA Self-replicating RNA acts as template on which polypeptide forms. Polypeptide Polypeptide acts as primitive enzyme that aids RNA replication.

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Surrounding membranes may have protected some of these molecular co-ops as they evolved rudimentary metabolism –Natural selection would have favored the most efficient co-ops –These may have evolved into the first prokaryotic cells

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Figure 16.6B, C Membrane RNA Polypeptide

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prokaryotes are the oldest life-forms –They remain the most numerous and widespread organisms on Earth today 16.7 Prokaryotes have inhabited Earth for billions of years PROKARYOTES Figure 16.7

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prokaryotes are cells that lack nuclei and other membrane-enclosed organelles 16.8 Archaea and bacteria are the two main branches of prokaryotic evolution

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prokaryotes are classified into two domains, based on nucleotide sequences and other features –Bacteria and Archaea Table 16.8

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Spheres (cocci) are the most common Rods (bacilli) 16.9 Prokaryotes come in a variety of shapes Figure 16.9A-C Curves or spirals

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These E. Coli colonies are growing with only glucose as an organic nutrient Prokaryotes obtain nourishment in a variety of ways Figure 16.10

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Autotrophs obtain carbon from CO 2 and are of two types –Photoautotrophs and chemoautotrophs Heterotrophs obtain carbon from organic compounds –Photo- heterotrophs and chemo- heterotrophs Table 16.10

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The first cells were most likely chemoautotrophs –They may have gotten their energy from sulfur and iron compounds

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Archaea live in –anaerobic swamps –salt lakes –acidic hot springs –deep-sea hydrothermal vents –animal digestive systems Archaea thrive in extreme environments— and in the ocean Figure 16.11A, B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Rotating flagella aid in locomotion Diverse structural features help prokaryotes thrive almost everywhere Figure 16.12A Flagellum Plasma membrane Cell wall Rotary movements of each flagellum

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pili help cells cling to surfaces Figure 16.12B Pili

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Endospores allow certain bacteria to survive environmental extremes in a resting stage Figure 16.12C Endospore

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Many prokaryotes grow in linear filaments Figure 16.12D

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These bacteria photosynthesize in a plant-like way –They often “bloom” in polluted water Connection: Cyanobacteria sometimes “bloom” in aquatic environments Figure 16.13A, B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Pathogenic bacteria can cause disease by producing –exotoxins, such as Staphylococcus aureus –endotoxins Lyme disease is caused by a bacterium carried by ticks Connection: Some bacteria cause disease Figure 16.14A, B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings In 1876, Robert Koch discovered rod-shaped bacteria in the blood of cattle suffering from anthrax Connection: Koch’s postulates are used to identify disease-causing bacteria Figure 16.15A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Koch’s postulates are a set of criteria that can prove that bacteria are the cause of disease Figure 16.15B Diseased animal Colony Suspected pathogen (from animal) grown in pure culture Bacterium identified Bacteria (pure culture of suspected pathogen) injected into healthy animal Disease occurs in second animal Bacteria from animal grown in pure culture Identical bacterium identified: the pathogen

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The species that causes anthrax can be used as a biological weapon in war or in acts of terrorism Connection: Bacteria can be used as biological weapons Figure 16.16

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Many prokaryotes are environmentally important in Earth’s chemical cycles –We exploit decomposers in sewage treatment Connection: Prokaryotes help recycle chemicals and clean up the environment Figure 16.17A Rotating spray arm Rock bed coating with aerobic bacteria and fungi Liquid wastesOutflow

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Prokaryotes hold a great potential for solving environmental problems such as oil spills and toxic mine wastes Figure 16.17B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Eukaryotic cells evolved from prokaryotic cells more than 2 billion years ago –The nucleus and endomembrane system of eukaryotes probably evolved from infoldings of the plasma membrane of ancestral prokaryotes The eukaryotic cell probably originated as a community of prokaryotes PROTISTS Figure 16.18A Plasma membrane Cytoplasm Ancestral prokaryoteCell with nucleus and endomembrane system Endoplasmic reticulumNucleus Nuclear envelope

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Mitochondria and chloroplasts probably evolved from symbiotic prokaryotes that took up residence inside larger prokaryotic cells Figure 16.18B Aerobic heterotrophic prokaryote Some cells Ancestral host cellPhotosynthetic eukaryotic cell Mitochondrion Photosynthetic prokaryote Mitochondrion Chloroplast

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Early protists were the ancestors of plants, animals, and fungi The taxonomy of protists is in a state of flux Protists—unicellular eukaryotes and their close multicellular relatives—probably represent multiple kingdoms Figure 16.19

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings They include –flagellates Protozoa are protists that ingest their food Figure 16.20A, B –amoebas

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –apicomplexans –ciliates Figure 16.20C, D Red blood cell Apex Cilia Macronucleus Cilia Macronucleus

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Most protozoa live freely in water or moist soil –Some live in humans and other animals and cause disease

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Slime molds are protists that may constitute a distinct kingdom Cellular slime molds have both unicellular and multicellular stages Figure Amoeboid cells Sluglike colony Reproductive structure

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These slime molds have unicellular stages –They also have stages where they exist as plasmodia, multinuclear masses of cytoplasm undivided by membranes Plasmodial slime molds form brightly colored “supercells” with many nuclei Figure 16.22A, B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings They include –Unicellular dinoflagellates Photosynthetic protists are called algae Figure 16.23A Flagellar groove Flagellum

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings –Diatoms –Green algae Figure B, C

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings These protists are multicellular photosynthetic organisms that lack the structural specializations of plants Examples include –Brown algae –Red algae –Green algae Seaweeds are multicellular marine algae Figure 16.24A, B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Brown algae seem closely related to diatoms –These groups may eventually be classified with some other groups of protists in a separate kingdom Many biologists favor classifying red algae in their own kingdom Macronucleus

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Green algae are often classified in the plant kingdom –Their life cycles involve the alternation of generations Macronucleus Figure 16.24C Male gametophyte Meiosis Fusion of gametes Gametes Spores Mitosis Female gametophyte HAPLOID (n) DIPLOID (2n) Mitosis Zygote Sporophyte

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Multicellularity evolved independently many times –Probably by specialization of the cells of colonial protists Multicellular life may have evolved from colonial protists Figure Unicellular protist 1 Colony 2 Early multicellular organism with specialized, interdependent cells Locomotor cells Food- synthesizing cells Somatic cells 3 Later organism that produces gametes Gamete

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Multicellular life first arose over a billion years ago –All life was aquatic until almost 500 million years ago Multicellular life has diversified over hundreds of millions of years Figure Multicellular organisms colonize land Diverse multicellular algae, fungi, and animals, all living in the sea Mass extinctions Earliest animals; many multicellular algae Oldest known fossils of multicellular eukaryotes (small algae) Earliest multicellular eukaryotes? Age of fossils in millions of years PRECAMBRIAN ERA PALEOZOIC ERA