Marine Bacteria and Archaea

21 Pages·2015·1.74 MB·English

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Marine Bacteria and Archaea
Metabolic diversity
• Organisms have two fundamental nutritional needs:
• 1. Obtaining carbon in a form that can be used to
synthesize fatty acids, proteins, DNA, and RNA

• Autotrophs get their carbon from CO
2

• Heterotrophs get carbon from organic sources
vs
2
Metabolic diversity
• Organisms have two fundamental nutritional needs:
• 2. Acquiring chemical energy in the form of ATP

• Phototrophs: energy from light

• Lithotrophs (or Chemotrophs): energy from inorganic chemicals
such as H S, ammonia NH , methane CH
2 3 4

• Organotrophs: energy from organic sources, such as sugars

3
Metabolic diversity
Category Energy source Carbon source Hydrogen or Examples
electron source
Photolithoautotrophy Light CO Inorganic Cyanobacteria,
2
purple sulfur
bacteria
Photoorganoautotrophy Light Organic compounds Organic compounds Purple non-sulfur
or H bacteria, aerobic,
2
anoxygenic bacteria,
archaea (?)

Chemolithoautotrphy Inorganic CO Inorganic Sulfur-oxidizing
2
bacteria, nitrifying
bacteria, archaea
Chemoorganoautotrophy Organic Organic compounds Organic compounds Wide range of
compounds bacteria and
archaea
Mixotrophy (combination Organic Organic compounds Inorganic Sulfur-oxidizing
of lithoautotrophy and compounds bacteria
organoheterotrophy)
Evolution of life
Prebiotic Precellular Early Evolutionary
LUCA
chemistry life cellular life diversification
4.3-3.8 bya 3.8-3.7 bya
Biological RNA Protein DNA Lipid Divergence of
building blocks world synthesis bilayers Bacteria and Archaea
Amino acids Catalytic RNA RNA – Replication Cellular Components of DNA
Nucleosides Self-replicating RNA templated Transcription compartments replication,
Sugars translation Early cells likely transcription, and
had high rates translation all in
of HGT place
Submarine mounds and
their possible link to the
origin of life.

Model of the interior of a
hydrothermal mound
with hypothesized
transitions from prebiotic
chemistry to cellular life
depicted

Differences between Archaea, Bacteria and Eukaryotes
Characteristic Bacteria Archaea Eukaryotes
Cell type Prokaryotic Prokaryotic Eukaryotic
Histones No histones Have proteins Have histones
similar to histones
Introns No introns Some introns Most contain
introns
Ribosome size 70S ribosomes 70S ribosomes 80S ribosomes
Cell wall Peptidoglycan Made of protein Not always present
composition (lack peptidoglycan) Plants: cellulose
plasma membrane Fungi: Chitin
Cell membrane Ester linked lipids Ester linked lipids Ester linked lipids
composition with D-Glycerol with L-Glycerol with proteinf
(straight chain) (branch chain) (straight chain)
Themes: Growth & reproduction by fission
A. Bacterium before B. DNA replication starts. C. The new copy of DNA
DNA replication. It proceeds in two is attached at a
Bacterial chromosome is directions membrane site near the
attached to the plasma parent DNA molecule.
membrane.
E. Deposits of new F. The ongoing deposition
D. New membrane grows
membrane and new wall of membrane and wall
between the two
material extend down material divides the cell in
attachment sites.
into the cytoplasm. two.
Themes: conjugation
nicked plasmid conjugation tube
A. A conjugation tube forms between a B. DNA replication starts on the nicked
donor and a recipient cell. An enzyme has plasmid. The displaced DNA strand moves
nicked the donor’s plasmid. through the tube and enters the recipient
cell.
C. In the recipient cell, replication starts on D. The cells separate from each other; the
the transferred DNA. plasmids circularize.