Chapter 13 EVOLUTION AND DIVERSITY AMONG THE MICROBES BACTERIA, ARCHAEA, PROTIST

Question

Chapter 13 EVOLUTION AND DIVERSITY AMONG THE MICROBES BACTERIA, ARCHAEA, PROTISTS, AND VIRUSES: THE UNSEEN WORLD Learning objectives Explain how microbes are different from other groups of organisms Describe the typical structures of a bacterial cell and their functions Characterize the various methods of lateral gene transfer in bacteria Discuss the role of normal flora in the body and probiotic therapy Describe concerns related to pathogenic bacteria Explain the significance of antibiotic resistance in bacteria and measures humans can take to reduce the proliferation of resistant bacteria Characterize the features of the major groups of sexually transmitted diseases Compare and contrast the features of archaea with bacteria and eukaryotes Describe the features of protists and differentiate between the three major groups of protists Describe the process of viral infection and replication Understand the concerns with certain viruses being able to cross species boundaries to cause infection. Explain the life cycle of the HIV virus Chapter outline I. There Are Microbes in All Three Domains are found just about everywhere, tend not to think about them much because we cannot see them. Unlike other groups of organisms that are categorized by their evolutionary relatedness, the primary criterion that distinguishes microbes from other groups of organisms is Microbes are among some of the most evolutionarily successful organisms for the reasons: 1. Microbes are genetically diverse. Approximately species of microbes are thought to exist.

Explanation / Answer

A microorganism or microbe is a microscopic organism, which may be single celledor multicellular . The study of microorganisms is called microbiology.Microorganisms are very diverse and include all bacteria,archaea, and most protozoa.This group also contains some fungi,algae,and some microorganisms such as rotifers. Some microbiologists classify virusesand viroids as microorganisms,but others consider these as nonliving

Microorganisms can be found in almost any where on Earth. Bacteria and archaea are almost always microscopic,while number of eukaryotes are also microscopic,including most protists,some fungi,as well as microanimals and plants.Viruses are generally regarded as not living and therfore not considerd as microorganisms although the field of microbiology includes virology, the study of viruses

Bacteria and archaea , the prokaryotes are the most diverse and abundant group of organisms

Bacteria

All most all bacteria are invisible to naked eye,They lack a nucleus and other membrane bound organelles ,and function and reproduce as individual cells , but offen aggregate in multicellular colonies.

Archaea

Archaea are also single celled organisms that lack nuclei and classified in kingdom Monera.Archaea differ from bacteria both their genetics and biochemistry.Bacterial cell membranes are made from phosphoglycerides with ester bonds,archaean membranes are made of ether lipids

Protists

Protists are unicellular, some are colonial or multicellular ,they do not have specialized tissue organization .The simple cellular organization distinguishes the protists from other eukaryotes.The body of the protists have a nucleus which is well defined and membrane bound organelles .Some have flagella or cilia for locomotion .Reproduction in protists is bith asexual and sexual

Characteristics Bacteria Archaea Eukaryotes Nuclear envelope Absent Absent Present Membrane enclosed organelles Absent Absent Present Peptidoglycan in cellwall Present Absent Absent Membrane lipids unbranched hydrocarbons some branched hydrocarbons unbranched hydrocarbons RNA polymerase one kind several kinds several kinds Intiator aminoacid for start of protein synthesis Formyl methionine Methionine Methionine Introns Absent Present in some genes Present Response to the antibiotics Growth inhibited Growth not inhibited Growth not inhibited Histones associated with DNA Absent Present Present Circular chromosome Present Present Absent Ability to grow at temperatures below100 c No some species No

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