Biology II Chapter 27 - 2
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What are autotrophs? What two modes of nutrition are under the autotroph category?
Organisms that need only an inorganic compounds such as CO2 as a carbon source.
Both carbon sources: CO2
Photoautotrophs (Energy source: Light) and Chemoautotrophs (Energy source: Inorganic chemicals) are included in the autotroph cateory.
What are heterotrophs? What two modes of nutrition are under the heterotroph category?
Organisms that require at least one organic nutrient, such as glucose, to make other organic compounds.
Both carbon source: Organic molecules
Photoheterotrophs (Energy source: Light) and chemoheterotrophs (Energy source: Organic compounds) are included in this category.
Compare and contrast Photoautotrphs and Photoheterotrophs.
Both require light
as their Energy Source.
- Photoautotroph carbon source: CO2
- Photosynthetic prokaryotes, plants and certain protists fall in this category.
- Photoheterotroph carbon source: Organic compounds
- Certain prokaryotes such as Rhodobacter and Chloroflexus fall in this category.
Compare and contrast Chemoautotrphs and Chemoheterotrophs.
Chemoautotrophs require inorganic chemicals as their energy source while chemoheterotrophs require organic compounds.
Chemoautotroph carbon source: CO2
Chemoheterotroph carbon source: Organic compounds
What is a photoautotroph?
Photosynthetic organisms that capture light energy and use it to drive the systhesis of organic compounds from CO2 or other inorganic carbon compounds.
Cyanobacteria and many other groups of prokaryotes are photoautotrophs, as are plants and algae.
What is a chemoautotroph?
Only need an inorganic compound such as CO2 as a carbon source. However, instead of using light as an energy source, they oxidize inorganic substances such as hydrogen sulfide (H2S), ammonia (NH3) or ferrous ions (Fe2+).
This mode of nutrition is unique to certain prokaryotes.
What is a photoheterotroph?
An organism that harness energy from light but must obtain carbon in organic form.
This mode is unique to certain marine and halophilic (salt-loving) prokaryotes.
What is a chemoheterotroph?
An organism that must consume organic molecules to obtain both energy and carbon.
This nutritional mode is widespread among prokaryotes.
What is an obligate aerobe?
An organism that requires oxygen for cellular respiration and cannot live without it.
What is an obligate anaerobe?
An organism that only carries out fermentation or anaerobic respiration. Such organisms cannot use oxygen and in fact may be poisoned by it.
What is anaerobic respiration?
The use of inorganic moleculars other than oxygen to accept elections at the "downhill" end of electron transport chains.
What is aerobic respiration?
A catabolic pathway that consumes oxygen and organic molecules, producing ATP. This is the most efficient catabolic pathway and is carried out in most eukaryotic cells and many prokaryotic organisms.
What is a catabolic pathway?
A metabolic pathway that releases energy by breaking down complex molecules to simpler compounds.
What are facultative anaerobes?
An organism that makes ATP by aerobic respiration if oxygen is present but switches to anaerobic respiration or fermentation if oxygen is not present.
(T/F) Nitrogen is essential for the roduction of amino acids and nucleic acids in all organisms.
(T/F) While eukaryotes can obtain nitrogen from only a limited group of nitrogen compounds, prokaryotes can metabolize nitrogen in a wide variety of forms.
What is the process known as nitrogen fixation?
The conversion of atmospheric nitrogen (N2) to ammonia (NH3). Biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants.
The nitrogen may then be turned into amino acids and other organic molecules.
What is a heterocyte? What is its significance?
A specialized cell that engages in nitrogen fixation in some filamentous cyanobacteria; formaly called heterocyst.
It allows for metabolic cooperation.
What is a biofilm?
A surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation.
Cells in a biofilm secrete signaling molecules that recruit nearby cells, causing the colonies to grow. The cells also produce proteins that stick the cells to the substrate and to one another.
Channels in the biofilm allow nutrients to reach cells in the interior and wastes to be expelled.
Distinguish between the four major modes of nutrition, not which are unique to prokaryotes.
A phototroph derives its energy from light, while a chemotroph get its energy from chemical sources
An autotroph derives its carbon from inorganic sources (often CO2) while a heterotroph get its carbon from organic sources.
Thus, there are four nutritional modes: photoautotrophic, photoheterotrophic (unique to prokaryotes), chemoautorophic (unique to prokaryotes) and chemoheterotrophic.
A bacterium requires only the amino acid methionine as an organic nutrient and lives in lightless caves. What mode of nutrition does it employ?
The bacterium must rely on chemical sources of energy since it is not exposed to light, and it must be a heterotroph if it requires an organic source of carbon rather than CO2 (or another inorganic source, like bicarbonate)
A ______ gene transfer obscures the location of the root of the tree of life.
horizontal gene transfer
What is an extremeophile?
A prokaryote in the Archaea domain that lives in an environment so extreme that few other organisms can survive there. It includes extreme halophiles (salt-loving) and extreme thermophiles (heat-loving).
"lovers" of extreme conditions (philos, lover)
What is an extreme halophile?
- (halo, salt)
- A prokaryote in the domain Archaea that lives in highly saline environments such as the Great Salt Lake, the Dead Sea, and Owens Lake.
Some species merely tolerate salinity, while others require an environment that is several times salter than seawater.
For example, the proteins and cell wall of Halobacterium
have unusual features that improve function in extremely salty environments but render these organisms incapable of survival if salinity drops below 9%.
What is an extreme thermophile?
- (thermos, hot)
- A prokaryote in the domain Archaea that thrives in very hot environments.
At temperatures as hot as 90C, the cells of most organisms die because their DNA does not stay together in a double helix, and many of their proteins denature. Extreme thermophiles avoids this fate because their DNA and proteins have adaptations that make them stable at high temperatures.
(T/F) Some archaea live in more moderate environments while the extremophiles live in extreme conditions.
However, this is all relative....
What are methanogens? Why were they given this name?
A group of archaea named for the unique way that they obtain energy. They use CO2 to oxidize H2, releasing methane as a waste product. Among the strictest of anaerobes, methanogens are poisoned by O2.
The "marsh gas" found in some swamps and marshes are produced by these archaea. Some other species of methanogens live within the guts of cattle, termites, and other herbivores. They may also be used as decomposers in sewage treatment facilities.
What group of prokaryotes function as decomposers? What do decomposers do?
Chemoheterotrophic prokaryotes function as decomposers. They use organic molecules as both the energy source and the carbon source.
Decomposers are any of the saprobic fungi and prokaryotes that absorb nutrients from nonliving organic material such as corpses, fallen plant material, and the wastes of living organisms and convert them to inorganic forms. They are detritivores.
Without the actions of prokaryotes and other decomposers such as fungi, all life would cease.
What are in the major group of bacteria Chlamydias?
Parasites that can survive only within animal cells, depending on their hosts for resources as basic as ATP.
The gram-negative walls of chlamydias are unusual in that they lack peptidoglycan. (Similar to Archaea then?....)
What are in the major group of bacteria Spirochetes?
Helical heterotrophs that spiral through their environment by means of rotating, internal, flagellum-like filaments.
Many are free-living but others are notorious pathogenic parasites.
What are in the major group of bacteria Cyanobacteria?
Photoautotrophs that are they only prokaryotes with plantlike, oxygen-generating photosynthesis.
Chloroplasts likely evolved from an endosymbiotic cyanobacterium.
Both solitary and colonial cyanobacteria are abundant wherever these is water, providing an enormous amount of food for freshwater and marine ecosystems.
What are in the major group of bacteria Gram-positive bacteria?
Gram-positive bacteria rival the proteobacteria in diversity. These include actinomycetes, some of which are free-living species that help decompose the organic matter in soil.
Also include solitary species such as Bacillus anthracis, which causes anthrax and Clostridium botulinum, which causes botulism.
What are included in the major group of bacteria known as Proteobacteria?
This is a large and diverse clade of gram-negative bacteria that includes photoautotrophs, chemoautotrophs, and heterotrophs.
Some proteobacteria are anaerobic, while others are aerobic.
It is categorized into 5 categories from alpha to epsilon.
Autotrophic prokaryotes have what function?
These prokaryotes convert inorganic compounds to forms that can be taken up by other organisms, such as the use of CO2 to make organic compounds.
Also, cyanobacteria produce atmospheric O2 and a variety of prokaryotes fix atmospheric nitrogen into forms that other organisms that can use to make the building blocks of proteins and nucleic acids.
What is symbiosis?
An ecological relationship between organism of two different species that live together in direct and intimate contact.
The larger organism is known as the host and the smaller is known as the symbiont.
What is mutualism?
An ecological interaction between two species in which both benefit.
What is commensalism?
An evological relationship in which one species benefits while the other is not harmed or helped in any significant way.
What is parasitism?
An ecological relationship in which a parasite eats the cell contents, tissues, or body fluids of its host. As a group, parasites harm but often do not kill their host, at least not immediately.
What is a pathogen?
An organism or virus that causes disease. Many parasites that cause diseases are typically prokaryotics.
(T/F) Many eukaryotes depend on mutualistic prokaryotes.
For example, human intestines are home to an estimated 500 to 1,000 species of bacteria.
Explain how molecular systematics has contributed to our understanding of prokaryotic phylogeny.
How has genetic prospecting contributed to our understanding of prokaryotic diversity and phylogeny?
Explain how individual prokaryotes, though small, can be considered giants in their collective impact on Earth and its life.
Although prokaryotes are small, their large numbers and metabolic abilities enable them to play key roles in ecosystems by decomposing wastes, recycling chemical and affecting the concentrations of nutrients available to other organisms.
Explain how the relationship between humans and Bacteroides thetaiotaomicron is an example of mutualism.
Bacteroides thetaiotaomicron, which lives inside the human intestine, benefits by obtaining nutrients from the digestive system and by receiving protection from competing bacteria from host-produced antimicrobial compounds to which it is not sensistive. The human host benefits because the bacterium manufacture carbohydrates, vitamins, and other nutrients. Which are then absorbed in the intestine.
What are exotoxins?
Proteins secreted by certain bacteria and other organisms.
What are endotoxins?
Lipopolysaccharide components of the outer membrane of gram-negative bacteria.
In contrast to exotoxins, endotoxins are released only when the bacteria die and their cell walls break down.
What is bioremediation?
The use of organisms, typically prokaryotes, to remove pollutants from soil, air, or water.
What are the two largest groups of bacteria?
(T/F) Horizontal gene transfer can spread genes associated with virulence to harmless strains.
What are the major groups of bacteria?
- Gram-positive Bacteria
Proteobacteria is a large and diverge clade of
a) gram-positive bacteria
b) gram-negative bacteria
Gram-positive bacteria are included in their own group.
This large and diverse clade of gram-negative bacteria includes photoautorphs, chemoautotrophs, and heterotrophs.
Some proteobacteria are anaerobic, while others are aerobic. The phylogenetic tree below shows the relationship based on molecular data.
(T/F) Gram-positive bacteria rival the proteobacteria in diversity.
Species in one subgroup, the actinomycetes, form colonies containing branched chains of cells. Two species of actinomycetes cause tuberculosis and leprosy.
However, most actinomycetes are free-living species that help decompose the organic matter in soil; their secretions are partly responsible for the "earthy" oder of rich soil.
(T/F) Chlamydias are parasites that can survive only within animal cells, depending on their hosts for resources as basic as ATP.
The gram-negative walls of chlamydias are unusual in that they lack peptidoglycan.
(T/F) Spirochetes are helical heterotyophs spiral through their environment by means of rotating, internal, flagellum-like filaments. Many spirochetes are free-living, but others are notorious pathogenic parasites.
(T/F) Cyanobacteria are photoautotrophs with plantlike, oxygen-generating photosynthesis.
Both solitary and colonial cyanobacteria are abundent whereever there is water, providing an enormous amount of food for freshwater and marine ecosystems.
Explain how molecular systematics has contrinuted to our understanding of prokaryotic phylogeny.
Before molecular systematics, taxonomists classified prokaryotes accoding to phenotypic characters that did not clarify evolutionary relationships. Molecular comparisons - of DNA in particular - indicate key divergences in prokaryotic lineages.
How has genetic prospecting contributed to our understanding of prokaryotic diversity and phylogeny?
By not requiring that organisms be cultured in the laboratory, genetic prospecting has revealed an immense diversity of previously unknown prokaryotic species. Over time, the ongoing discovery of new species by genetic prospecting is likely to alter our understanding of prokaryotic phylogeny greatly.
Genetic variation in bacterial populations cannot result from
a) light as an energy source and CO2 as a carbon source
b) light as an energy source and methane as a carbon source
c) N2 as an energy source and CO2 as a carbon source
d) CO2 as both an energy source and a carbon source
e) H2S as an energy source and CO2 as a carbon source
Which of the following statements is not true?
a) Archaea and bacteria have different membrane lipids.
b) Both archaea and bacteria generally lack membrane enclosed organelles.
c) The cell walls of archaea lack peptidoglycan.
d) Only bacteria have histones associated with DNA.
e) Only some archaea use CO2 to oxidize H2, releasing methane.
Which of the following features of prokaryotic biology involves metabolic cooperation among cells?
a) binary fission
b) endospore formation
c) endotoxin release
Which prokaryotic group is mismatched with its members?
a) Proteobactera - diverse gram-negative bacteria
b) Gram-positive bacteria - symbionts in legume root nodules
c) Spirochetes - helical heterotrophs
d) Chlamydias - intracellular parasites
e) Cyanobacteria - solitary and colonial photoautotrophs
Gram-positive bacteria consist of free-living species that help decompose the organic matter in soil.
Plantlike photosynthesis that releases O2 occurs in
e) chemoautotrophic bacteria
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