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59 Cards in this Set
- Front
- Back
How many PK species are known and about how many exist?
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5k and 400k to 4M
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Are archaea more closely related to bacteria or eukarya?
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eukarya
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What are the three PK shapes?
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cocci (spheres), bacilli (rods), and helices
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What is the average range of PK sizes?
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1 to 5 μm
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How does a cell wall assist in osmoregulation?
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Cell walls prevent bursting in a hypotonic environment, but in a hypertonic environment cause the cell to plasmolyze, or shrink away from the wall and die.
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What are bacterial cell walls made of?
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peptidoglycan, sugars cross-linked with short polypeptides
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What structure do Gram-positive bacterial cell walls have?
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lots of peptidoglycan on the outside of a plasma membrane
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What structure do Gram-negative bacterial cell walls have?
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two membranes with some peptidoglycan between and lipopolysaccharides extending from the surface
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Which are more dangerous, gram-negative or gram-positive bacteria and why?
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gram-negative, because they are more protected and some lipopolysaccharides are toxic
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What do penicillins target?
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cross-links in the peptidoglycan, breaking down the wall with no effect on the host (humans)
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What does the capsule do?
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protects the PK further and glues PKs to surfaces and together into colonies
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What are pili (pilus) and what do they do?
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surface appendages that attach to surfaces or others and help exchange DNA
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How do PKs in general move?
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Flagella, smaller than eukaryotic flagella, move them.
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How do spirochetes move?
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helical filaments inside the cell wall rotate, sending these helices forward like corkscrews
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What is movement toward or away from a stimulus called?
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taxis
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How is PK DNA organized?
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1 double-stranded DNA ring is twisted and gnarled into a blob known as the nucleoid region.
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How many chromosomes do PKs have?
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one major chromosome, along with smaller plasmids that aren't essential
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What do plasmids do?
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contain genes for antibiotic resistance, unusual metabolism, and can be exchanged between cells
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How do PK ribosomes compare to eukaryotic ribosomes and why does it matter?
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PK ribosomes are smaller and have different proteins and RNA, allowing tetracycline and chloramphenicol to target PK ribosomes.
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How do PKs reproduce?
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asexual binary fission
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What are the three mechanisms for gene transfer among PKs?
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transformation (taking genes up from the environment), conjugation (direct transfer between two cells), and transduction (via viruses)
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What is an endospore and what does it do?
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Resistant bacterial cells made when a new membrane is formed around a copy of the chromosome, they last a long time.
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What photosynthesize from carbon dioxide?
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photoautotrophs, including cyanobacteria as well as plants and algae
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What chemosynthesize using carbon dioxide?
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chemoautotrophs, a subset of PKs
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What photosynthesize but cannot use carbon dioxide?
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photoheterotrophs, a subset of PKs
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What cannot make their own light or organic carbon?
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chemoheterotrophs, including some from all kingdoms
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What nutritional mode do most PKs utilize?
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chemoheterotrophs
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What is another name for decomposers?
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saprobes
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Which steps in the nitrogen cycle are controlled by bacteria?
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ammonium to nitrite, nitrate to nitrogen gas, and nitrogen gas to ammonium
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What cyanobacteria cells fix atmospheric nitrogen?
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heterocysts
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What use O2 for cellular respiration and require it to live?
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obligate aerobes
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What will use O2 but can live without it?
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facultative aerobes
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What are poisoned by O2?
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obligate anaerobes
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How many times did photosynthesis evolve?
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once
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How is PK phylogeny derived?
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Signature sequences in small-subunit ribosomal RNA identify two organisms as more closely related.
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What are the three classifications of extremophiles?
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methanogens (make methane from CO2 and H2, extreme anaerobes), extreme halophiles (love salt, purple-red due to bacteriorhodopsin), and extreme thermophiles (love heat, first life near deep sea vents?)
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Do all archaea live in harsh environments?
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No, some live in more moderate parts of the ocean.
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What are the two taxa of Archaea?
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Euryarchaeota (methanogens, halophiles, some thermophiles) and Crenarchaeota (thermophiles)
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What do archaea have in common with bacteria but not eukarya?
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no nuclear envelope or membraned organelles, and a circular chromosome
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What do archaea have in common with eukarya but not bacteria?
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no peptidoglycan, methionine as the first amino acid in a sequence, some introns, no response to streptomycin or chloramphenicol, and histones
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What are the five major bacterial clades?
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proteobacteria (α, β, γ, δ, ε), chlamydias, spirochetes, gram-positive bacteria, and cyanobacteria
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What do α proteobacteria have in common?
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most are symbionts with eukaryotic hosts, mitochondria evolved from them
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What are examples of α proteobacteria?
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Rhizobium (nitrogen fixers in legume roots), Agrobacterium (make tumors in plants), and rickettsias (very small pathogens of animals)
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What is an example of a β proteobacterium?
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Nitrosomonas, which converts ammonium to nitrite
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What are examples of γ proteobacteria?
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Chromatium (yellow sulfur chemosynthesizers), Legionelle (Legionnaires' disease), enterices (live in animal intestines) such as Salmonella (food poisoning), Vibrio cholerae (cholera), and Escherichia coli (in human intestine and feces)
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What are two groups of δ proteobacteria?
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Myxobacteria make colonies that glide through soil, while bdellovibrio change speeds rapidly and drill prey at 100 rpm.
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What is an example of a ε proteobacteria?
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Helicobacter pyloci, which causes stomach ulcers
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What make chlamydia special?
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They depend on their host for virtually everything, and their gram-negative walls have no peptidoglycan.
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What are two examples of spirochete pathogens?
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Treponema pallidum causes syphilis and Borrelia burgdorferi causes Lyme disease.
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What do actinomycetes do?
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A branch of gram-positive bacteria, they form colonies, cause TB and leprosy, decompose litter, and include the genus Streptomyces, used to make streptomycin.
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Besides actinomycetes, what are other examples of gram-positive bacteria?
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Sporers Bacillus and Clostridium include Bacillus anthacis (anthrax) and Clostridium botulinum (botulism), also Staphylococcus, Streptococcus, and mycoplasmas.
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What make mycoplasmas special?
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They are the smallest of all known cells (diameter .1 μm) and lack cell walls. Somehow that makes them gram-positive.
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What makes cyanobacteria special?
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They are the only PKs that photosynthesize with oxygen, like plants, and in addition fix nitrogen.
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How are prokaryotes essential to any environment?
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They cycle nutrients where none else can, and can metabolize lots of inorganic stuff like iron, sulfur, nitrogen and hydrogen.
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What are opportunistic pathogens and what is an example?
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normally there, they attack when the body's defenses are down, such as Streptococcus pneumoniae
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What are Koch's postulates, the four things to do in order to be able say that a pathogen causes a disease?
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1) Find the pathogen in everyone with the disease.
2) Isolate it and grow it in a pure culture. 3) Induce it in experimental animals from the culture. 4) Isolate the same pathogen from the diseased animals once it develops. |
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What are exotoxins?
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proteins secreted by pathenogenic PKs that cause illness
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What are endotoxins?
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components of the outer membranes of gram-negative bacteria
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What are 3 ways humans use PKs?
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1) E. coli is used for experimental purposes.
2) Bioremediation: to remove pollutants from water/air/soil. 3) to produce commercial products such as acetone and butanol as well as yogurt and cheese. |