An Overview of Microbial Life - PowerPoint PPT Presentation

1 / 53
About This Presentation
Title:

An Overview of Microbial Life

Description:

An Overview of Microbial Life Chapter 2 * * Top picture: Pyrolobus archaeon that grows optimally above the boiling point of water Bottom pictures: Extreme acidophile ... – PowerPoint PPT presentation

Number of Views:223
Avg rating:3.0/5.0
Slides: 54
Provided by: utaEdubio
Category:

less

Transcript and Presenter's Notes

Title: An Overview of Microbial Life


1
An Overview of Microbial Life
  • Chapter 2

2
Elements of Cell and Viral Structures
  • 3 Domains Archae, Eubacteria, Eukaryota
  • Two structural types of cells are recognized the
    prokaryote and the eukaryote.
  • Prokaryotic cells have a simpler internal
    structure than eukaryotic cells, lacking
    membrane-enclosed organelles.
  • Viruses
  • Viruses are not cells but depend on cells for
    their replication.

3
Cells from each domain
Eukarya
Bacteria
Archae
4
The basic components..
  • All microbial cells share certain basic
    structures in common, such as cytoplasm, a
    cytoplasmic membrane, ribosomes, and (usually) a
    cell wall.
  • Note Animal cells typically do not have a cell
    wall
  • The major components dissolved in the cytoplasm
    include
  • Macromolecules
  • Inorganic ions

5
Eukaryotic Cells
  • Larger and structurally more complex
  • Euk. microorganisms include algae, fungi and
    protozoa
  • Membrane enclosed organelles
  • Nucleus
  • Mitochondria
  • Chloroplasts (photosynthetic cells only)

6
Prokaryotic Cells
  • Lack membrane enclosed organelles
  • Include Bacteria and Archae
  • Smaller than eukaryotic cells (Typically 1-5 um
    long and 1um in width)
  • However, can vary greatly in size

7
Viruses
  • Not cells
  • Static structures which rely on cells for
    replication and biosynthetic machinery
  • Many cause disease and can have profound effects
    on the cells they infect
  • Cancer, HIV
  • However, can alter genetic material and improve
    the cell

8
(No Transcript)
9
Arrangement of DNA in Microbial Cells
  • Genes govern the properties of cells, and a
    cell's complement of genes is called its genome.
  • DNA is arranged in cells to form chromosomes.
  • In prokaryotes, there is usually a single
    circular chromosome whereas in eukaryotes,
    several linear chromosomes exist.

10
Nucleus vs. Nucleoid
  • Nucleus a membrane-enclosed structure that
    contains the chromosomes in eukaryotic cells.
  • Nucleoid aggregated mass of DNA that constitutes
    the chromosome of cells of Bacteria and Archaea

11
(No Transcript)
12
Prokaryotic DNA
  • Most DNA is circular
  • Most have only a single chromosome
  • Single copy of genes
  • Haploid
  • Many also contain plasmids

13
Plasmids
  • Plasmids are circular extrachromosomal genetic
    elements (DNA), nonessential for growth, found in
    prokaryotes.
  • Typically contain genes that confer special
    properties (ie unique metabolic properties)
  • Useful in biotechnology

14
(No Transcript)
15
Eukaryotic DNA
  • Organized into linear molecules
  • Packaged into chromosomes
  • Number varies
  • Typically contain two copies of each gene
  • Diploid

16
Genes, genomes, and proteins
  • E.coli genome a single circular chromosome of
    4.68 million base pairs
  • of genes 4,300
  • A single cell contains
  • 1,900 different proteins
  • 2.4 million protein molecules
  • Abundance of proteins varies

17
Genome size, complexity, and the C-value paradox
  • Genome size does not necessarily correlate with
    organismal complexity

18
In actuality.
19
The Tree of Life
  • Evolution change in allelic frequencies over
    generations
  • The evolutionary relationships between life forms
    are the subject of the science of phylogeny.
  • Phylogenetic relationships are deduced by
    comparing ribosomal sequences

20
(No Transcript)
21
The three domains of life
  • Comparative ribosomal RNA sequencing has defined
    the three domains of life Bacteria, Archaea, and
    Eukarya.

22
What has this sequencing revealed??
  • Molecular sequencing has shown that the major
    organelles of Eukarya have evolutionary roots in
    the Bacteria
  • Mitochondria and chloroplasts were once
    free-living cells that established stable
    residency in cells of Eukarya eons ago.
  • The process by which this stable arrangement
    developed is known as endosymbiosis.

23
What has this sequencing revealed?? Cont.
  • Although species of Bacteria and Archaea share a
    prokaryotic cell structure, they differ
    dramatically in their evolutionary history.
  • Archae are more closely related to eukaryotes
    than are species of bacteria

24
Molecular sequencing and microbiology
  • Overall rRNA sequencing technology has helped
    reveal the overall evolutionary connections
    between all cells
  • In particular prokaryotes
  • Impacted subdispiciplines
  • Microbial classification and ecology
  • Clinical diagnostics
  • Can identify organisms without having to culture
    them

25
Microbial Diversity
  • Cell size and morphology
  • Metabolic strategies (physiology)
  • Motility
  • Mechanisms of cell division
  • Pathogenesis
  • Developmental biology
  • Adaptation to environmental extremes
  • And many more

26
Physiological Diversity of Microorganisms
  • All cells need carbon and energy sources
  • Energy can be obtained in 3 ways
  • Organic chemicals
  • Inorganic chemicals
  • Light
  • Types of physiological diversity
  • Chemoorganotrophs
  • Chemolithotrophs
  • Phototrophs
  • Heterotrophs and Autotrophs
  • Habitats and Extreme environments

27
(No Transcript)
28
Chemoorganotrophs
  • Chemoorganotrophs obtain their energy from the
    oxidation of organic compounds.
  • Energy conserved as ATP
  • All natural and even synthetic organic compounds
    can be used as an energy source
  • Aerobes
  • Anaerobes
  • Most microorganisms that have been cultured are
    chemoorganotrophs

29
Chemolithotrophs
  • Chemolithotrophs obtain their energy from the
    oxidation of inorganic compounds.
  • Found only in prokaryotes
  • Can use a broad spectrum of inorganic compounds
  • Advantageous because can utilize waste products
    of chemoorganotrophs

30
Phototrophs
  • Phototrophs contain pigments that allow them to
    use light as an energy source.
  • ATP generated from light energy
  • Cells are colored
  • Oxygenic photosynthesis
  • O2 involved
  • Cyanobacteria and relatives
  • Anoxygenic photosynthesis
  • No O2
  • Purple and green bacteria

31
Autotrophs and Heterotrophs
  • All cells require carbon as a major nutrient
  • Microbial cells are either
  • Autotrophs use carbon dioxide as their carbon
    source, whereas heterotrophs use organic carbon
    from one or more organic compounds.
  • Autotrophs considered primary producers
  • Synthesize organic matter from CO2 for themselves
    and that of chemoorganotrophs
  • All organic matter on earth has been synthesized
    from primary producers

32
Habitats and Extreme Environments
  • Microorganisms are everywhere on Earth that can
    support life
  • Extremophiles organisms inhabiting extreme
    environments
  • Boiling hot springs,
  • Within ice, extreme pH, salinity, pressure

33
Examples of Extremophiles
34
Prokaryotic Diversity
  • Several lineages are present in the domains
    Bacteria and Archaea
  • An enormous diversity of cell morphologies and
    physiologies are represented
  • rRNA analysis has shown dramatic differences in
    phenotypic characteristics within a given
    phylogenetic group

35
Bacteria
36
Proteobacteria
  • The Proteobacteria is the largest division
    (called a phylum) of Bacteria
  • A major lineage of bacteria that contains a large
    number of gram(-) rods and cocci
  • Represent majority of known gram(-) medical,
    industrial, and agricultural bacteria of
    significance
  • Extreme metabolic diversity
  • Chemorganotrophs E.coli
  • Photoautotrophs Purple sulfur bacterium
  • Chemolithotrophs Pseudomonas, Aztobacter
  • Pathogens Salmonella, Rickettsia, Neisseria

37
Proteobacteria examples
Chemolithotrophic sulfur-oxidizing bacteria
Achromatium
Neisseria gonorrhoeae
38
Gram-positive bacteria
  • United by a common cell wall structure
  • Examples
  • Spore forming
  • Clostridium, Bacillus
  • Antibiotic producing
  • Streptomyces
  • Lactic acid bacteria
  • Streptococcus
  • Lactobacillus
  • Mycoplasmas
  • Lack cell wall
  • Small genomes
  • Often pathogenic

39
Cyanobacteria
  • The Cyanobacteria are phylogenetic relatives of
    gram-positive bacteria and are oxygenic
    phototrophs.
  • First oxygenic phototrophs to have evolved on
    Earth

40
Planctomyces
  • Characterized by distinct cells with stalks that
    allow for attachment to solid surfaces
  • Aquatic

41
Spirochetes
  • Helical shaped
  • Morphologically and phylogenetically distinct
  • Widespread in nature and some cause disease
  • Most notable sp cause Syphilis and Lyme Disease

Spirochaeta zuelzerae
42
Green sulfur and non-sulfur bacteria
  • Contain similar photosynthetic pigments
  • Can grow as autotrophs
  • Chloroflexus
  • Inhabits hot springs and shallow marine bays
  • Dominant organism in stratified microbial mats
  • Important link in the evolution of photosynthesis

43
Chlamydia
  • Most species are pathogens
  • Obligate intracellular parasites
  • How would this affect an immune response?

44
Deinococcus
  • Contain sp with unusual cell walls and high level
    of resistance to radiation
  • Cells usually exist in pairs or tetrads
  • Can reassemble its chromosome after high radiation

45
Aquifex, Thermotoga, Env-OP2
  • Sp that branch early on the tree
  • Unified in that they grow at very high temps
    hyperthermophily
  • Inhabitats of hot springs

46
Archaea
  • There are two lineages of Archaea the
    Euryarchaeota and the Crenarchaeota
  • Many are extremophiles
  • All are chemotrophic
  • Many using organic carbon
  • While others are chemolithotrophs

47
Euryarchaeota Crenarchaeota
  • Physiologically diverse groups
  • Many inhabit extreme environments
  • From extreme pH, temperature, salinity

48
Limitations of Phylogenetic analyses
  • Not all Archaea are extremophiles
  • Difficult to culture
  • Based on molecular microbial ecology, the extent
    of diversity is much greater than once thought

49
Eukaryotic Microorganisms
  • Collectively, microbial eukaryotes are known as
    the Protista.
  • Microbial eukaryotes are a diverse group that
    includes algae, protozoa, fungi, and slime molds
  • Cells of algae and fungi have cell walls, whereas
    the protozoa do not.
  • The early-branching Eukarya are structurally
    simple eukaryotes lacking mitochondria and other
    organelles
  • Ex Giardia

50
Eukaryotic microbial diversity
51
Eukaryotic microbial diversity
  • Diplomonads flagellates, many are parasitic
  • Ex Giardia lamblia (synonymous with Lamblia
    intestinalis and Giardia duodenalis) is a
    flagellated protozoan parasite flagellated
    protozoan parasite
  • Trichomonads anaerobic protist, many are
    pathogenic
  • Ex. Trichomonas vaginalis
  • Flagellates all protozoa in this group utilize
    flagella for motility, free-living, and
    pathogenic
  • Ex. Trypanosomes
  • Slime molds resemble fungi and protozoa
  • Ex. Dictyostelium discoideum

52
Fungi
Protozoa
Algae
53
Lichens
  • Some algae and fungi have developed mutualistic
    associations called lichens.
Write a Comment
User Comments (0)
About PowerShow.com