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59 Cards in this Set

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