4: Microbial Diversity
- Page ID
- 42482
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\dsum}{\displaystyle\sum\limits} \)
\( \newcommand{\dint}{\displaystyle\int\limits} \)
\( \newcommand{\dlim}{\displaystyle\lim\limits} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\(\newcommand{\longvect}{\overrightarrow}\)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Life appeared on Earth approximately 3.7 billion years ago. For a billion years all life was prokaryotic and mainly anaerobic until eukaryotes evolved from a symbiosis between a larger archaeal cell and aerobically-respiring bacteria in response to increasing levels of atmospheric oxygen. In this symbiosis, aerobic respiration was critical to providing the high levels of energy necessary to support the evolution of the large, complex eukaryotic cells we are familiar with today.
In the course of 3.7 billion years, prokaryotes have evolved to take advantage of almost every imaginable carbon and energy source in every possible niche and environment. This has resulted in a huge diversity of microbial life, which today is formally classified through a taxonomic system based on evolutionary relationships (phylogeny) and informally based on organismal characteristics (phenotype). Some of the most familiar groups of microbes are discussed here as representatives of this diversity.
Chapter 4 BIOL 235 Learning Outcomes
- Provide a rough timeline of the evolution of life on Earth, including: formation of the Earth, first cells, increase in atmospheric oxygen, first eukaryotes, multicellular life, humans.
- Describe the endosymbiotic theory for the evolution of certain eukaryotic organelles and provide at least three pieces of evidence to support the theory.
- In the framework of the endosymbiotic theory and environmental conditions at the time of the evolution of eukaryotic cells, explain the benefits of the relationship to both host and symbiont.
- Describe both the beneficial and harmful implications of the reactivity of oxygen.
- Explain how either phenotype characteristics or molecular characteristics (phylogeny) can be used to classify organisms.
- Order the levels of classification from more general to more specific, from domain to strain.
- Explain why ribosomal sequences are a good choice for determining relationships of organisms.
- Use a phylogenetic tree to determine an organism’s closest relatives.
- Properly apply the terminology for nutritional types (metabolic lifestyles): chemo/phototroph, auto/heterotroph.
- Describe the major characteristics of the following taxonomic groups: Bacteria (Domain), Archaea (Domain), Eukaryotes (Domain), Cyanobacteria (Phylum), Firmicutes (Phylum), Proteobacteria (Phylum), Bacillus (Genus), Clostridium (Genus).
- List the characteristics commonly associated with Archaea, in particular the thermophiles, halophiles, and methanogens.
- Give one characteristic NOT associated with Archaea.
- Given a description of an organism, select the taxonomic group (of those above) with which the organism would best be classified.
- 4.1: Taxonomy and Evolution
- This page covers the evolution of life on Earth, starting with microbial cells and their metabolic diversity, photosynthesis, and the Great Oxidation Event. It explains endosymbiosis for eukaryotic cell origins and introduces phylogeny and taxonomy for classifying organisms. Additionally, it discusses defining microbial species through genotypic, phenotypic, and polyphasic methods, highlighting the importance of genetic traits, ecological niches, and collaborative functions in classification.
- 4.2: A Systematic Approach
- This page covers the classification of microorganisms, tracing the evolution of taxonomy from Linnaeus's hierarchical system and binomial nomenclature to modern genetic methods that recognize three domains: Archaea, Bacteria, and Eukarya. It notes the complexities introduced by horizontal gene transfer and emphasizes the significance of Bergey's manuals for bacterial identification using traditional methods.
- 4.3: Representative Groups
- This page discusses prokaryotes, unicellular microorganisms without nuclei, highlighting their adaptability to various environments and their metabolic versatility. It examines key groups like Proteobacteria and Archaea, noting their ecological significance and impact on human health, including oxygen production and toxin degradation. The chapter emphasizes the diversity, structure, and ecological roles of prokaryotes in ecosystems.
Thumbnail: "Hot water running over mineral and bacteria deposits yellowstone wyoming wy" by Tim Pearce, Los Gatos is licensed under CC BY 2.0