Biology 27: Bacteria and Archaea
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54 terms
Terms | Definitions |
|---|---|
 cocci | spherical |
| bacilli | rod-shaped |
| staphylococci | grapelike clusters of cocci |
| diplococci | cocci growing in pairs |
| streptococci | cocci occurring in pairs or chains |
| peptidoglycan | bacterial cell walls contain ______, a network of sugar polymers cross-linked by polypeptides |
| archaea | contain polysaccharides and proteins but lack peptidoglycan |
| Gram-positive | bacteria that have simpler walls with relatively large amounts of peptidoglycan |
| Gram-negative | bacteria that have less peptidoglycan in their cell walls and are structurally more complex |
| capsule | a dense and well-defined layer of polysaccharide or protein that surrounds the cell wall and is sticky, protecting the cell and enabling it to adhere to substrates or other cells |
| fimbriae | short, hairlike appendages of a prokaryotic cell that help it adhere to the substrate or to other cells |
| pili | structures that link one cell to another at the start of conjugation |
| taxis | an oriented movement toward or away from a stimulus, such as a bacteria orienting based upon gravity |
| exaptation | existing structures take on new functions through descent with modification |
| nucleoid region | part of the prokaryote that contains most of the genome and is not surrounded by a membrane |
| plasmid | a small ring of independently replicating DNA molecules |
| endospores | metabolically inactive forms of prokaryotes which can remain viable in harsh conditions for centuries |
| transformation | a change in genotype and phenotype due to the assimilation of external DNA by a cell, which is not directed |
| transduction | a process in which phages (viruses) carry bacterial DNA from one bacterial cell to another |
| conjugation | a process in which genetic material is transferred between bacterial cells |
| phototrophs | organisms that obtain energy from light |
| chemotrophs | organisms that obtain energy from chemicals |
| autotrophs | organisms that need CO2 only in some form |
| heterotrophs | organisms that require at least one organic compound in order to synthesis other organic compounds |
| obligate aerobes | must use O2 for cellular respiration |
| obligate anaerobes | are poisoned by O2, and use fermentation or final electron acceptors other than O2 |
| facultative anaerobes | can survive with or without O2 |
| nitrogen fixing | a process by which atmospheric nitrogen (N2) is converted into ammonia (NH3) |
| heterocytes | nitrogen-fixing cells in cyanobacterium Anabaena, which has separate photosynthetic cells |
| biofilm | a surface-coating colony of one or more species of prokaryotes that engage in metabolic cooperation |
| extremophiles | archaea that live in environments which other organisms could not tolerate |
| extreme halophiles | archaea that live in highly saline environments |
| extreme thermophiles | archaea that live in very hot environments |
| methanogens | archaea that live in swamps and marshes and produce methane as a waste product |
| proteobacteria | diverse clade of gram-negative bacteria containing photoautotrophs, chemoautotrophs, and heterotrophs (alpha, beta, gamma, delta, epsilon) |
| alpha proteobacteria | many species are associated with eukaryotic hosts, such as rhizobium's root nodules in legumes and agrobacterium's plant tumors |
| beta proteobacteria | nutritionally diverse subgroup which includes Nitrosomonas, which converts NH4+ to NO2- |
| gamma proteobacteria | includes sulfur bacteria such as Chromatium, and pathogens such as Legionella, Salmonella, E. Coli, and Vibrio cholerae |
| epsilon proteobacteria | group contains many pathogens including Campylobactera which causes septicemia, and Helicobacter pylori, which causes stomach ulcers |
| chlamydias | gram-negative parasites of human cells; trachomatis causes blindness and nongonococcal urethritis (STDs) |
| spirochetes | helical heterotrophs with flagella-like filaments: syphilis and Lyme disease |
| cyanobacteria | only prokaryotes with plant-like photosynthesis, make up phytoplankton, plant chloroplasts likely evolved (endosymbiosis) |
| actinomycetes | Gram-positive bacteria which decompose soil, form colonies, and are responsible for tuberculosis and leprosy |
| Gram-positive | Bacillus anthracis (anthrax), Clostridium botulinum (botulism), Staphylococcus, and Streptococcus |
| mycoplasms | the smallest known cells, some of which contain as few as 500 genes, and lack cell walls |
| chemoheterotrophic prokaryotes | function as decomposes, breaking down corpses, dead vegetation, and waste products |
| symbiosis | an ecological relationship in which two species live in close contact: a larger host and smaller symbiont |
| mutualism | symbiotic relationship in which both host and symbiont benefit from relationship |
| commensalism | symbiotic relationship in which one species benefits and the other is neither helped nor harmed significantly |
| parasitism | an ecological relationship in which an organism eats parts of its host, usually harming but not killing the host |
| half | parasites cause about _____ of human diseases |
| exotoxins | poisons that cause disease even if the prokaryotes that secrete them are not present |
| endotoxins | poisons that are released only when bacteria die and their cell walls break down |
| bioremediation | the use of organisms to remove pollutants from the environment |
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