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Chapter 27 Bacteria & Archaea
First Life on Earth Earth’s first organisms were likely prokaryotesProkaryotes are divided into two domains: archaea and bacteria Members of Domain Archaea are composed of Kingdom Archaeabacteria; they are found in the harshest environments Members of Domain Bacteria are composed of Kingdom Eubacteria; they are found everywhere else © 2011 Pearson Education, Inc.
Structural and Functional Adaptations of ProkaryotesMost prokaryotes are unicellular, although some species form colonies Most prokaryotic cells are 0.5–5 µm, much smaller than the 10–100 µm of many eukaryotic cells Prokaryotic cells have a variety of shapes The three most common shapes are spheres (cocci), rods (bacilli), and spirals (spirilli) © 2011 Pearson Education, Inc.
1 m 1 m 3 m (a) Spherical (b) Rod-shaped (c) Spiral Figure 27.2Figure 27.2 The most common shapes of prokaryotes. 1 m 1 m 3 m (a) Spherical (b) Rod-shaped (c) Spiral
Cell-Surface StructuresAn important feature of nearly all prokaryotic cells is their cell wall, which maintains cell shape, protects the cell, and prevents it from bursting in a hypotonic environment Eukaryote cell walls are made of cellulose (plants) or chitin (fungi) Bacterial cell walls contain a network of polysaccharides cross-linked by proteins A polysaccharide or protein layer called a capsule covers many prokaryotes © 2011 Pearson Education, Inc.
Bacterial capsule Bacterial cell wall Tonsil cell 200 nm Figure 27.4Figure 27.4 Capsule. 200 nm
Motility Many bacteria exhibit taxis, the ability to move toward or away from a stimulus Most bacteria propel themselves by flagella scattered about the surface or concentrated at one or both ends Flagella of bacteria, archaea, and eukaryotes are composed of different proteins and likely evolved independently © 2011 Pearson Education, Inc.
Internal Organization and DNAThe prokaryotic genome has less DNA than the eukaryotic genome The chromosome is circular and not surrounded by a membrane; it is located in the nucleoid region Some species of bacteria also have smaller rings of DNA called plasmids © 2011 Pearson Education, Inc.
Reproduction and AdaptationProkaryotes reproduce quickly by binary fission and can divide every 1–3 hours Key features of prokaryotic reproduction: They are small They reproduce by binary fission They have short generation times © 2011 Pearson Education, Inc.
Prokaryotes are not “primitive” but are highly evolved Many prokaryotes form metabolically inactive endospores, which can remain viable in harsh conditions for centuries Prokaryotes are not “primitive” but are highly evolved Their short generation time allows prokaryotes to evolve quickly For example, adaptive evolution in a bacterial colony was documented in a lab over 8 years © 2011 Pearson Education, Inc.
Genetic Diversity in ProkaryotesProkaryotes have considerable genetic variation Three factors contribute to this genetic diversity: Rapid reproduction Mutation Genetic recombination © 2011 Pearson Education, Inc.
Genetic RecombinationGenetic recombination, the combining of DNA from two sources, contributes to diversity Prokaryotic DNA from different individuals can be brought together by transformation, transduction, and conjugation Movement of genes among individuals from different species is called horizontal gene transfer © 2011 Pearson Education, Inc.
Nutritional and Metabolic Adaptations in ProkaryotesProkaryotes can be categorized by how they obtain energy and carbon Phototrophs obtain energy from light Chemotrophs obtain energy from chemicals Autotrophs require CO2 as a carbon source Heterotrophs require an organic nutrient to make organic compounds © 2011 Pearson Education, Inc.
The Role of Oxygen in MetabolismProkaryotic metabolism varies with respect to O2 Obligate aerobes require O2 for cellular respiration Obligate anaerobes are poisoned by O2 and use fermentation or anaerobic respiration Facultative anaerobes can survive with or without O2 © 2011 Pearson Education, Inc.
Metabolic CooperationCooperation between prokaryotes allows them to use environmental resources they could not use as individual cells In some prokaryotic species, metabolic cooperation occurs in surface-coating colonies called biofilms © 2011 Pearson Education, Inc.
Molecular systematics in Prokaryotic PhylogenyUntil the late 20th century, systematists based prokaryotic taxonomy on phenotypic criteria Applying molecular systematics to the investigation of prokaryotic phylogeny has produced dramatic results Molecular systematics led to the splitting of prokaryotes into bacteria and archaea © 2011 Pearson Education, Inc.
Prokaryotes Roles in the BiosphereProkaryotes are so important that if they were to disappear the prospects for any other life surviving would be dim Chemoheterotrophic prokaryotes function as decomposers, breaking down dead organisms and waste products The ecological communities of hydrothermal vents depend on chemoautotropic bacteria for energy © 2011 Pearson Education, Inc.
Ecological InteractionsSymbiosis is an ecological relationship in which two species live in close contact: a larger host and smaller symbiont Prokaryotes often form symbiotic relationships with larger organisms © 2011 Pearson Education, Inc.
In mutualism, both symbiotic organisms benefit In commensalism, one organism benefits while neither harming nor helping the other in any significant way In parasitism, an organism called a parasite harms but does not kill its host Parasites that cause disease are called pathogens © 2011 Pearson Education, Inc.
Prokaryotes: Beneficial and Harmful Impacts on HumansProkaryotes cause about half of all human diseases For example, Lyme disease is caused by a bacterium and carried by ticks © 2011 Pearson Education, Inc.
Pathogenic prokaryotes typically cause disease by releasing exotoxins or endotoxinsExotoxins are secreted and cause disease even if the prokaryotes that produce them are not present Endotoxins are released only when bacteria die and their cell walls break down © 2011 Pearson Education, Inc.
Prokaryotes in Research and TechnologyExperiments using prokaryotes have led to important advances in DNA technology For example, E. coli is used in gene cloning For example, Agrobacterium tumefaciens is used to produce transgenic plants Bacteria can now be used to make natural plastics © 2011 Pearson Education, Inc.
Prokaryotes are the principal agents in bioremediation, the use of organisms to remove pollutants from the environment Bacteria can be engineered to produce vitamins, antibiotics, and hormones Bacteria are also being engineered to produce ethanol from waste biomass © 2011 Pearson Education, Inc.
Prokaryotes They’re almost everywhere. Prokaryotes were the first organism and persist today as the most numerous and pervasive of all living things.
Prokaryotic diversity Eubacteria & Archaebacteria Campbell & Reese Fig 26.1.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings PowerPoint Lectures for Biology, Seventh Edition Neil Campbell and Jane Reece.
Chapter 27 Bacteria & Archaea.
BACTERIA AND ARCHAEA.
+ Bacteria and Archaea. + Cell surface markers of prokaryotes Most bacteria contain peptidoglycan in their cell walls, which is a polymer of modified.
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell.
CHAPTER 27 BACTERIA and ARCHAEA 1. OVERVIEW 1. Earliest organisms on Earth 2. Dominate biosphere 3. Live everywhere 4. Commonly referred to as “bacteria”
AP Biology Archaebacteria & Bacteria Classification Old 5 Kingdom system Monera, Protists, Plants, Fungi, Animals New 3 Domain system reflects.
PROKARYOTES. THEY ARE EVERYWHERE The Major Similarities Between the Two Types of Cells (Prokaryote and eukaryote) Are: They both have DNA as their genetic.
Chapter 18. Domain Archaea Only one kingdom: Archaebacteria ▪ Cells contain cell walls ▪ Live in extreme environments (hot, acidic, salty, no O 2.
18.1 Bacteria Objectives: 8(C) Compare characteristics of taxonomic groups, including archaea, bacteria, protists, fungi, plants, and animals. 11(C) Summarize.
Chapter 27: The Prokaryotes Objectives 1.Learn about the prokaryotic adaptations that make them successful, including the diverse metabolic pathways. 2.Learn.
Regents Biology Ch Viruses Overview: A Borrowed Life Viruses called bacteriophages can infect and set in motion a genetic takeover of bacteria,
Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Bacteria Staphylococcus bacteria in nose.
Prokaryotes Chapter 27. Found wherever there is life; thrive in habitats that are too cold, too hot, too salty, etc. Most live in symbiotic relationships.
Bacteria and Archaea. Prokaryotes Structure, Function, and Reproduction Nutritional and Metabolic Diversity Phylogeny of Prokaryotes Ecological Impact.
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings CHAPTER 27 Prokaryotes.
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