Ch. 7

• eukaryote reproduction


  asexual or sexual, haploid or diploid
• bacteria/archaea reproduction


  haploid and asexual (binary fission, budding, filamentous); must replicate and segregate genome
• bacterial cell cycle


  DNA replication and partition -> cytokinesis
• replisome


  proteins needed for DNA synthesis; push daughter chromosomes to opposite ends of cell
• MreB


  actin homolog; plays role in segregation and spiral shape
• septation


  formation of walls between daughter cells
• FtsZ


  tubulin homolog; forms z-ring
• vibrio (comma-shaped)


  FtsZ forms z-ring -> MreB does helical polymerization ->crescentin (filament homolog) forms curve through asymmetric cell wall synthesis
• water activity (aw)


  water available; Psoln / Pwater
• halophiles


  salt concentration of .2 M and up
• extreme halophiles 


  salt concentration of 2 M - 6 M
• mechanosensitive channels


  channels in membrane that allows solutes to leave when cell is in hypotonic solution to prevent lysing
• acidophiles


  pH 0 - 5.5
• neutrophiles


  pH 5.5 - 7
• alkaliphiles


  pH 8.5 - 11.5
• acid tolerance responses


  pump protons out of the cell, produce acidic or basic waste products into environment
• protective enzymes


  SOD, catalase, and peroxidase; produced in aerobes because oxygen can easily be reduced into toxic species
• biofilms


  microbes attach to a conditioned surface and release polysacs, proteins, and DNA to form extracellular polymeric substance (EPS); interactions occur btwn attached micros
• quorum sensing


  AHL (autoinducer molecule) diffuses across the membrane and induces expression of target genes; seen in mostly gram-negative species, involved in bioluminescence, antibiotic resistance, and virulence
• stationary starvation response


  morphological changes (endospore formation), decrease in size (protoplast shrinkage), and RpoS protein assists in RNA transcription for starvation proteins
• generation time


  (Y)2^Z; where y = original number of cells and z = number of cycles
• direct cell counts


  flow cytometry (electric counting) and counting chambers
• viable cell counts


  spread + pour and membrane filters
• cell mass measurement


  dry weight, quantity of a certain cell constituent ( e.g. DNA), or light scattering (turbidometric)