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Chapter 27 (Prokaryotes (Archaea (Halobacterium (Are among the most salt…
Chapter 27
Prokaryotes
lives in salt water, lives in hard conditions, with dramatic color that is caused not by minerals or other nonliving sources, but by living things. Live in environments that are too cold or too hot for most other organisms, and some have found living in rocks below the Earth's surface.
Archaea
They have red membrane pigments, some of which capture light energy that is used to drive ATP synthesis.
Halobacterium
Are among the most salt-tolerant organisms on Earth; they thrive in salinities that dehydrate and kill other cells. Cell compensates foe water lost through osmosis by pumping potassium ions into the cell until the ionic concentration inside the cell matches the concentration outside.
Peptidoglycan
A polymer composed of modified sugar cross-linked by short polypeptides. This molecular fabric enclose the entire bacterium and anchors other molecules that extend from its surface.
Gran stain
Technique developed by the 19th-century Danish physician Han Christian Gram, scientists can categorize many bacterial species according to differences in cell wall composition.
Gram-Positiveb
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Gram-Negative
Have less peptidoglycan and are structurally more complex, with an outer membrane that contains lipopolysaccharides (carbohydrates bonded to lipids).
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Endospores
Withstanding harsh conditions, certain bacteria develop resistant cells is called endospores when they lack water or essential nutrients.
Fimbriae
Some prokaryotes stick to their substrate or to one another by means of hairlike appendages called fimbriae.
Taxis
A direct movement toward or away from a stimulus (from the Greek taxis, to arrange).
Nucleoid
A region of cytoplasm that is not enclosed by membrane. In addition to its single chromosome, a typical prokaryotic cell may also have much smaller rings of independently replicating DNA molecules called plasmid.
Archaea
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Extremophilies
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Extreme Halophiles
(SALT!!!!) Live in highly saline environments, such as the Great Salt Lake in Utah, the Dead Sea in Israel.
Extreme thermosphiles
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Methanogens
Moderate environments. archaea that release methane as a by-product of their unique ways of obtaining energy.
Decomposers
Breaking down dead organisms as well as waste products and thereby unlocking supplies of carbon, nitrogen and other elements.
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Host
In general, the larger organism in a symbiotic relationship is known as host, and the smaller is known as the symbiont.
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Commensalism
An ecological relationship in which one species benefits while other is not harmed or helped in any significant way.
Parasitism
An ecological relationship in which parasiteeats the cell contents, tissue, or body fluid of its host.
Transduction
1) A phage infects bacterial cell that carriers the A+ and B+ alleles on its chromosome (brown). This bacterium will the "donor." 2) The phage DNA is replicated, and the cell makes many copies of phage proteins (represented as purple dots). Certain phage proteins halt the synthesis of proteins encoded by host cell's DNA, and the host cell's DNA may be fragmented, as shown here. 3) As new phage particles assemble, a fragment of bacterial DNA carrying at A+ allele happens to be packaged in a phage capsid. 4) The phage carrying the A+ allele from from the donor cell infects a recipient cell with with alleles A- and B-. Crossing over at two sites (dotted lines) allows donor DNA (brown) to be incorporated into recipient DNA (green). 5) The genotype of the resulting recombinant cell (A+B-) differs from the genotypes of the donor (A+B+) and the recipient (A-B-).
In transduction, phages (from "bacteriophages," the viruses that infect bacteria) carry prokaryotic genes from one host cell to another. A virus the carries prokaryotic DNA may not be replicate because it lacks some or all of its own genetic material.
Conjugation
DNA transferred between two prokaryotic cells (usually of the same species) that are temporarily joined. One cell donates the DNA, and the other receives it.
Obligate aerobes
Obligate anaerobes
Anaerobic Respiration
Facultative Anaerobes
Use O2 if it is present but can also carry out fermentation or anaerobic respiration in an anaerobic environment.
Nitrogen Fixation
Some cyanobacteria and some methanogens (a group of archaea) convert atmospheric nitrogen (N2) to ammonia (NH3), a process called nitrogen fixation.
Heterocysts
Most cells in a filament carry out only photosynthesis, while a few specialized cells celled heterocyst (sometimes called heterocytes carry out nitrogen fixation.
Biofilms
Metabolic cooperation between different prokaryotic species often occurs in surface-coating colonies known as biofilms.Cells in a biofilm secrete signaling molecules that recruit nearby cells, causing the colonies to grow.
others extract chemical energy in which substances other than O2, such as nitrate ions (NO3-) or sulfate ions (SO4*2-), accept electrons at the "downhill" end of electron transport chain.
On the other hand, are poisoned by O2.
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Bacteria
Bacteria include that vast majority of prokaryotic species species familiar to most people, from pathogenic species that cause strep throat and tuberculosis to the beneficial species.
Proteobacteria
Large and diverse clade of gram-negative bacteria includes photo-autograph, chemoautotrophs, and heterotrophs. some are anaerobic, while others are aerobic.
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