Biology Bacteria and Archaea 26
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earliest prokaryote fossils date back at least ______ years
Prokaryotes play key roles in:
- 1. Organic breakdown
- 2. Nutrient cycling
- 3. Diseases of humans and otherorganisms
- 4. Bioremediation
In 1977, ______ (at Univ of Illinois) revised tree of life into three domains- _________- using differences in the ____ to determine relationships between the organisms.
Carl Woese/ eukaryotes, bacteria and archaea/rRNA
eukaryotes and______ are more closely related than
•Among the Bacteria, three shapes are common:
-Sphere or coccus (plural cocci), occur singly or in plates, blocks, or clusters.-Rod—bacillus (plural bacilli)-Helical-Rods and helical shapes may form chains.
•Morphology of known species of Archaea includes _____, _____, _________, and _______
cocci, bacilli, triangular, and square-shaped; the latter grow on surfaces, arranged like sheets of postage stamps.
Communities of different species of prokaryotes, including microscopic eukaryotes, excrete a gel-like polysaccharide matrix.
______ may be impenetrable to antibiotics.
Bacterial cell walls have_________, a polymer of amino sugars.
Archaea do not have__________, although some have a similar molecule called________________.
- peptidoglycan, peptidoglycan
Gram-positive bacteria retain the violet dye; they have a _____ layer of peptidoglycan outside the plasma membrane
Gram-negative bacteria retain the red dye; they have a____ layer of peptidoglycan between the plasma membrane and another distinct outer membrane, in the periplasmic space
____________interfere with the synthesis of the cell walls, but don’t affect eukaryote cells.
Antibiotics such as penicillin
- •Bacteria can monitor the size of the population by sensing the amount
- of chemical signal present.
When numbers are large enough, activities such as biofilm formation can begin.
Often the bacteria only emit light when a quorum has been sensed.
do not use oxygen as an electron acceptor in respiration.
molecular oxygen will kill these oxygen-sensitive prokaryotes
can shift their metabolism between aerobic and anaerobic modes, such as fermentation
perform photosynthesis using light as the energy source, and CO2 as their carbon source.
are bacteria that also use light as an energy source, but get carbon from organic compounds made by other organisms
get their energy by oxidizing inorganic compounds, and use the energy to fix CO2 as their carbon source.
obtain both energy and carbon from complex organic compounds
Flowchart of nutritional mode of organisms
3 reasons why nucleotide sequencing of ribosomal RNA is useful in evolutionary studies:
-rRNA is evolutionarily ancient and all free-living organisms have rRNA
-rRNA has the same role in translation in all organisms, lateral transfer is unlikely
-rRNA has evolved slowly; sequence similarities are easily found
Lateral gene transfer
occurs when genes from one species become incorporated into the genome of another species (moving “sideways” in the tree).
transfer by plasmids or virus, and uptake of DNA via transformation
•Transfer can occur between the domains.
hardy weinburg/isotopic decay
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•Over __ clades of bacteria have been proposed under the currently accepted classification scheme.
We will focus on examples from __ clades
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