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43 Cards in this Set
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prokaryotes
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1 micron in diameter
very large surface to volume ratio pili flagella, secretion needles shape: cocci (spheres) bacilli (rods) spirilla (spirals) have a glycocalyx outer membrane and periplasm found in gram negatives only cell wall present in all eubacteria except mycoplasma p-bilayer present cytoplasm: undifferentiated organelles: not membrane bound, DNA: circular chromosomes, sometimes linear Cell division: binary fission Endospores: formed predominantly in gram positive bacteria |
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eukaryotes
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flagella
found in some species no outer membrane or periplasm don't contain component of peptidoglycan has cytoskeleton and cytoplasmic streaming always membrane bound organelles DNA: paired chromosomes Cell division: mitosis for growth, meiosis for reproduction size: 10 microns |
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unrestricted growth
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dn/dt=KN, growth is exponential
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balanced growth
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constant growth at a steady rate, rarely achieved in the microbial world
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phases of growth
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lag phase: time for bacterial cell to sense it's in the nutrient rich environment
exponential phase: very short, exhaustion of nutrients, buildup of toxic compounds stationary phase: period of substantial cellular adjustments where cells can no longer grow (death and growth balanced) death: constant rate of loss by cells |
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bacterial habitats
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Everywhere, has commensal, symbiotic and parasitic relationships
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normal flora
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humans are made up of more bacterial cells than human cells
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probiotics
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live microorganisms that when administered in adequate amounts confer health benefit on host
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parasitic/pathogenic
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association of a microbe where host is harmed or killed
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biofilms
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complex communities of microbes that survive when subjected to environmental insult
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strict aerobes
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pseudomonas, depend only on oxygen
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strict anaerobes
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sensitive to oxygen (Bacterioides, Clostridium)
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Facultative anaerobes
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E. Coli, Strep. pneumoniae, can grow with or without oxygen. Aerobic metabolism yields 32 ATP,s anaerobic yields 2 ATP's
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Generation of ATP
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i). chemiosmosis: ATP production that is coupled to electron transport across a membrane
ii). substrate level phosphorylation: generation of a highly reactive phosphate bond as a metabolic intermeidate and transfer that bond to ADP to make ATP fermentation: recycles NAD+ for use in oxidative phosphorylations |
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prototrophs v auxotrophs
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bacteria have no requirements for organic compounds (proto)
bacteria that have more complex nutritional requirements (auxo) |
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gram stain
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stain crystal violet meant to identify bacterial type
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gram positive
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thick cell wall, only inner membrane, stain gets retained in thick cell wall
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gram negative
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double membrane, thin cell wall, presence of periplasm place, presence of LPS and lipid A on outer membrane, more resistant to antibiotics and other degradative chemicals
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B subunit RNA pol
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catalytic activity
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B' subunit
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allows RNA pol to bind to and stay bound to DNA
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alpha subunit
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plays an important role in interaction with regulator proteins
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sigma factor
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necessary for recognition of promoter region
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actinomycin D
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binds to DNA, rendering it unusuable as a template
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rifampicin
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blocks translocation after first translation
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SOS response
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involves lexA, recA repressor gets activated in UV light and then degrades LexA repressor, along for SOS gene to be expressed
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gram (-) signaling molecules
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homoserine lactones
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gram (+) signaling molecules
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peptides
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Viruses
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Can be either double stranded DNA or RNA, or can be single stranded, consists of a protein coat (capsid) and maybe a lipid membrane derived from host. Contractile sheath, tail fibers!
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Viral Development
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1). Adsorption
2). Penetration (injection, receptor mediated endocytosis) membrane fusion 3). gene expression of viral DNA 4). synthesis of proteins involved in nucleic acid replication 5). synthesis of structural proteins |
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Phage Receptors
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Polysaccharides
O-antigen (LPS) Porins Sialic acid (eukaryotes) |
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Adsorption
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Tail fibers make contact with capsid, porin, etc, reversible in contact. But once tail fibers flex, we have beginnig!
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Contraction
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Contractile sheath allow for injection of nucleic acids into periplasm, where they are transported by DNA transporters
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T4 bacteriophage
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binds to ompC porin (high osmolarity)
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MS2
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ssRNA, circular phage, rolls down pilus until it makes contact with the membrane
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PFU assay
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take bacteria and put on agar, make a bacterial lawn and then plate phages or bacterially infected cells on it
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bacterially infected cells plating on lawn
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have a sigmoidal curve, latent period
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phages infecting on the lawn
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have a curve that comes flat and has a faster period
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difference between eclipse period and latent period
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shows that there is a lag time, there is a need to produce various factors and proteins, including late and early DNA, and etc to form virions
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average burst size
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# PFU/infected cells
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T4 bacteria phage
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dsDNA linear, rollinc circle replication, T4 completed capsid swallows off more than one genome, duplicated genes results in possibilities for recombination
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phage lambda
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rolling circle, virus has certain 1 genome length, ssDNA complementary ends, sticky, area of religation is called cos site!
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bacteria and phage mutation dynamics
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bacteria try to fend themselves off with mutations in receptors, restriction endonucleases
viruses respond by mutating tail fibers, or finding means to avoid restriction endonucleases |
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phage therapy
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panacea of therapies, 1940's goes against modern notion of antibiotics. However it can work! Still exploring possibilities.
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