Chapter 2 (Chapter not in Text)
An Overview of Microbial Life
2.1 Elements of Cell Structure
A. Cell Wall - Bacteria and Plants
B. Cell Membrane (Cytoplasmic Membrane)
C. Macromolecules
i.
Proteins
ii. Nucleic Acids
iii. Lipids
iv. Polysaccharides
D. Small Organic Molecules
i.
Sugars
ii. Fatty Acids
iii. Nucleotides
iv. Amino Acids
v. Other (eg: Communication Molecules)
E. Inorganic Ions
F. Ribosomes
G. Nucleus/Nucleoid
2.2 Prokaryote and Eukaryote
A. Comparison**
B. Arrangement of DNA in Prokaryotic and
Eukaryotic Cells
i.
Prokaryotes
a. Nucleoid
b. Single Chromosome
c. Circular
d. Haploid - one copy of each gene
e. Extra-chromosomal DNA - Plasmid
f. Fission
ii.
Eukaryotes
a. Nucleus
b. Multiple Chromosomes
c. Linear
d. Diploid/Haploid
e. Mitosis and Meiosis
2.3 Viruses
A. Obligate “Parasites”
B. Infect Virtually all Cells
C. Unable to Carry Out Independent Metabolism
D. No Growth
E. Small
F. “Degenerative Cells” and “Borrowed”
Components
2.4 Evolutionary Relationships
A. Three Groups of Cellular Lineages
i.
Archaea
ii. Bacteria
iii. Eukarya
B. Classification and Nomenclature
i.
Genus
ii. Species Epithet
iii. Escherichia coli
iv. E. Coli
2.5. Tree of Life
A. Evolutionary Chronometer – evolutionary distance
between two organisms can be measured by
differences in nucleotide or amino acid sequence of
monomers in homologous macromolecules (DNA, RNA,
Protein).
16S and 18S rRNA – Standard Chronometers
Ribosomal Database Project (RDP)
Over 16,000 aligned 16S rRNA sequences
Over 8,000 aligned 18S rRNA sequences
http://rdp.cme.msu.edu/html/
B. Three Domains of Life – Archaea, Bacteria,
Eukarya
2.6 Microbial Diversity
A. Physiological Diversity – Energy is derived from
three sources: Organic carbon, Inorganic chemicals,
Light
Chemoorganotrophs – Bacteria, Archaea, Eukarya
Chemolithotrophs – Bacteria, Archaea
Phototrophs – Bacteria, Archaea, Eukarya (plants)
Carbon derived from two sources: Organic carbon,
Inorganic carbon.
Heterotrophs – Organic carbon
Autotrophs – Inorganic carbon
B. Tolerance to Environmental Extremes
Bacteria and Archaea
2.7 Prokaryotic Diversity
A. Bacteria – Either gram-negative, positive or
variable.
Proteobacteria: largest phylum (eg: E.
coli, Pseudomonas: aeruginosa). Gramnegative, show extreme metabolic
diversity, represent majority of known
gram-negative bacteria of medical,
industrial and agricultural significance.
Gram-positive bacteria: include
endospore-forming Bacillus and
Clostridia as well as antibiotic forming
Streptomyces. Lactobacillus and
Streptococcus are important in dairy
products and decay of plant material
Mycoplasma is related to gram-positives
but lack a cell wall.
Cyanobacteria (related to gram
positives) are closely related to algae
and higher plants.
Green Sulfur and Green Nonsulfur
bacteria include photosynthetic
organisms
Spirochetes are medically important and
have a unique morphology
Chlamydia are obligate intracellular
parasites
Aquifex and Thermotoga are
thermophiles
B. Archaea – More closely related to Eukarya
than to bacteria. All are chemotrophic
and many are lithotrophic. Most are
known to exist in extreme environments
(eg: acid springs, boiling water, under
high pressure, in hypersaline waters,
etc.)
Methanogens – unique metabolism,
responsible for production of all natural
gas.
C. Eukarya - All multicellular life forms are Eukarya.
All “higher” Eukarya are in symbiotic
relationships with prokaryotes. Many
eukaryotic cells contain endosymbiotic
prokaryotes. Many are microscopic,
which include: protozoa, fungi, algae
and slime molds.