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Biodiversity
Chapter 27 vocab
44
Biology
Undergraduate 1
03/16/2011

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Term
peptidoglycan
Definition
a type of polymer in bacterial cell walls consisting of modified sugars cross-linked by short polypedtides
Term
Gram stain
Definition
a staining method that distinguishes between two different kinds of bacterial cell walls
Term
Gram-positive
Definition
describing the group of bacteria that have a cell wall that is structurally less complex and contains more peptidoglycan than the cell wall of gram-negative bacteria. ___ bacteria are usually less toxic than gram-negative bacteria
Term
Gram-negative
Definition
describing the group of bacteria that have a cell wall that is structurally more complex and contains less peptidoglycan than the cell wall of gram-positive bacteria. ___ are often more toxic than gram-positive bacteria.
Term
capsule
Definition
a sticky layer that surrounds the cell wall of some prokaryotes, protecting the cell surface and sometimes helping to glue the cell to surfaces
Term
fimbria
Definition
a short, hairlike sppendage of a prokaryotic cell that helps it adhere to the substrate or to other cells; also known as an attachment pilus.
Term
sex pilus
Definition
in bacteria, a structure that links one cell to another at the start of conjugation
Term
taxis
Definition
an oriented movement toward or away from a stimulus
Term
nucleoid
Definition
a dense region of DNA in a prokaryotic cell
Term
plasmid
Definition
one of a family of closely related organelles that includes chloroplasts, chromoplasts, and amyloplasts (leucoplasts). ___ are found in cells of photosynthetic organisms
Term
endospore
Definition
a thick-coated, resistant cell produced by a bacterial cell exposed to harsh conditions
Term
transformation
Definition
a change in the genotype and phenotype due to the assimilation of external DNA by a cell
Term
transduction
Definition
a type of horizontal gene transfer in which phages (viruses) carry bacterial DNA from one host cell to another
Term
conjugation
Definition
in prokaryotes, the direct transfer of DNA between two cells (of the same or different species) that are temporarily joined. In ciliates, a sexual process in which two cells exchange haploid micronuclei
Term
F factor
Definition
In bacteria, the DNA segment that confers the ability to form pili for conjugation and associated functions required for the transfer of DNA from donor to recipient. The ___ may exist as a plasmid or be integrated into the bacterial chromosome
Term
F plasmid
Definition
the plasmid form of the F factor
Term
R plasmid
Definition
a bacterial plasmid carrying genes that confer resistance to certain antibiotics
Term
photoautotroph
Definition
an organism that harnesses light energy to drive the synthesis of organic compounds from carbon dioxide
Term
chemoautotrophs
Definition
an organism that needs only carbon dioxide as a carbon source but obtains energy by oxidizing inorganic substances
Term
photoheterotrophs
Definition
An organism that uses light to generate ATP but must obtain carbon in organic form
Term
chemoheterotrophs
Definition
an organism that must consume organic molecules for both energy and carbon
Term
obligate aerobe
Definition
an organism that requires oxygen for cellular respiration and cannot live without it
Term
obligate anaerobe
Definition
an organism that only carries out fermentation or anaerobic respiration. such organisms cannot use oxygen and in fact may be poisoned by it
Term
anaerobic respiration
Definition
the use of inorganic molecules other than oxygen to accept electrons at the "downhill" end of electron transport chains
Term
facultative anaerobe
Definition
an organism that makes ATP by aerobic respiration if oxygen is present but that switches to anaerobic respiration or fermentation if oxygen is not present
Term
nitrogen fixation
Definition
The conversion of atmospheric nitrogen to ammonia. biological nitrogen fixation is carried out by certain prokaryotes, some of which have mutualistic relationships with plants
Term
heterocytes
Definition
an organism that obtains organic food molecules by eating other organisms or substances derived from them
Term
biofilms
Definition
a surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation
Term
extremophiles
Definition
an organism that lives in an environment whose conditions are so extreme that few other species can survive there. ___ they include extreme halophiles and extreme thermophiles
Term
extreme halophiles
Definition
an organism that lives in a highly saline environment, such as the Great Salt Lake or the Dead Sea
Term
extreme thermophiles
Definition
An organism that thrives in hot environments (often 60-80C or hotter)
Term
methanogens
Definition
an organism that obtains energy by using carbon dioxide to oxidize hydrogen, producing methane as a waste product; all known ___ are in domain Archaea.
Term
decomposer
Definition
an organism hat absorbs nutrients from nonliving organic material such as corpses, fallen plant material, and the wastes of living organisms and converts them to inorganic forms; a detrivore
Term
symbiosis
Definition
an ecological relationship between organisms of two different species that live together in direct and intimate contact
Term
host
Definition
the larger participant in a symbiotic relationship, serving as home and food source for the smaller symbiont
Term
symbiont
Definition
the smaller participant in a symbiotic relationship, living in or on the host
Term
mutualism
Definition
a symbiotic relationship in which both participants benefit
Term
commensalism
Definition
a symbiotic realtionship in which one organism benefits but the other is neither helped nor harmed
Term
parasitism
Definition
A symbiotic relationship in which one organism benefits at the expense of another by living either within or on the host.
Term
parasite
Definition
an organism that feeds on the cell contents, tissues, or body fluids of another species (the host) while in or on the host organism. ___ harm but usually do not kill their host.
Term
pathogen
Definition
an organism or virus that causes disease
Term
exotoxin
Definition
A toxin protein that is secreted by a prokaryote or other pathogen and that produces specific symptoms, even if the pathogen is no longer present
Term
endotoxins
Definition
A toxic component of the outer membrane of certain gram-negative bacteria that is released only when the bacteria die.
Term
bioremediation
Definition
the use of organisms to detoxify and restore polluted and degraded ecosystems.
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