Bacteria & Archaea Terms Flashcards
Koch’s Postulates 1
the microbe must be present in individuals suffering from the disease and absent in healthy individuals
Koch’s Postulates 2
the microbe must be isolated in grown in pure culture
Koch’s Postulates 3
Injection of the microbe (from the pure culture) into a healthy animal should cause the disease symptoms to appear
Koch’s Postulates 4
the microbe should be isolatable again from the disease animal and shown to be identical in size, shape, and color to the original microbe
Louis Pasteur (1822-1895) argued that “germs” were the cause of human disease
Germ Theory
Bacteria can live on mucilage substrate to form colonies
Biofilms
Tooth decay is the result of chemical produced by
bacteria
plaque consists of ____________ and _____________
bacteria; mucilage
Only ________ species of bacteria and archaea have been named and described
5000
How many species of bacteria live in the human digestive tract?
over 400
how many species of bacteria live in the lining of the human stomach?
about 128
how many species of bacteria live in the human mouth?
approximately 500
Penicillin mode of action
prevents the cross-linking of small peptide chains in peptidoglycan, the main wall polymer of bacteria; pre-existing cells are unaffected but all newly produced cells grow abnormally, unable to maintain their wall rigidity, and they are susceptible to osmotic lysis
Introduction of live “friendly” bacteria into a patient’s digestive tract
Probiotics
infusions of human fecal flora in patients with inflammatory bowel disease, irritable bowel syndrome, and chronic constipation
bacteriotherapy
ecological importance of bacteria
-co-exist with other organisms just as they do with us
-many amphibian species have natural bacteria that fight off fungal infections
-decomposition & dentrification
stage 1of bioremediation
fertilizing contaminated sites to encourage the growth of existing bacteria and archaea that degrade toxic compounds
stage 2 of bioremediation
“seeding” or adding specific species of bacteria and archaea to contaminated sites
lack a nucleus
prokaryotes
have a nucleus
eukaryotes
prokaryotes are a ________________ group
paraphyletic
common features of prokaryotes (bacteria + archaea)
-absence of a nucleus, membrane-enclosed cytoplasmic organelles, cytoskeleton
-unicellularity
-presence of DNA, RNA, enzymes to transcribe and translate genetic code into protein
-binary fission vs. mitosis
bacteria is a ____________ clade
monophyletic
shared traits for bacteria
-circular DNA molecule; not in nucleus
-no membrane-bound cytoplasmic organelles
-no cytoskeleton
-no mitosis, nistead fission
thick layer of peptidoglycan in cell walls
Gram positive
thin layer of peptidoglycan in cell walls
Gram negative
Evidence that Archaea and Eukarya are more closely related than bacteria
“Signature” rRNA sequence found in all tested Archaea and Eukarya and no Bacteria
frequently live in extreme habitats
-extreme salinity, low oxygen, high temps, high or low pH
Archaea
Synapomorphies for Archaea
-absence of peptidoglycan in cell walls
-many unique genes
-unique lipids in cell membrane
Habitat of Archaea
-hot (thermophilic)
-acidic (acidophilic)
-animal guts (anaerobic methanogens)
thermophilic and acidophilic; Yellowstone hot springs
Crenarchaeota
some are methanogens; others halophilic, thermophilic, Deep Ocean Vents
Euryarchaeota
abundant in oceans, mesophilic
Thaumarchaeota
Some found in hot springs
Korarchaeota
Parasite of another archaea
Nanoarchaeota
-low GC Gram positive
-most are coccus and bacillus shaped
-some members are extremely common in human gut
-some members used to ferment dairy products
firmicutes
-high GC Gram positive
-share similar structures to fungus (mycelia) - originally classified as Actinomyces
-streptomyces genus is a huge source of antibiotics used in medicine today
Actinobacteria
-distinguished by their corkscrew shape and flagella (whip like tail)
-both syphilis and Lyme disease are caused by this bacteria
spirochaetes
-coccus shaped
-all known species are parasitic
-STD chlamydia is from this group
Chlamydiae
-also ‘purple bacteria’
-mitochondria of eukaryotes derived from species of this group
-diverse metabolically
-E. coli, Rhizobium, Vibria cholerae, Salmonella typhimurium
Proteobacteria
-blue-green bacteria (also formerly “blue-green algae”)
-photosynthetic
-single cells or colonies
cyanobacteria
