Microbial Cells PDF

Microbial cells Linfeng Huang Associate Professor of Biology BIOL 212 Microbiology  Cell Morphology Morphology: cell shape Major morphologies of prokaryotic cells (Figure 2.1) coccus (pl. cocci): spherical or ovoid rod/bacill...

Microbial cells Linfeng Huang Associate Professor of Biology BIOL 212 Microbiology  Cell Morphology Morphology: cell shape Major morphologies of prokaryotic cells (Figure 2.1) coccus (pl. cocci): spherical or ovoid rod/bacillus: cylindrical spirillum: curved or spiral Some stay grouped/clustered after cell division in characteristic arrangements (e.g., chains of Streptococcus, cubes of Sarcina, grapelike clusters of Staphylococcus). spirochetes (tightly coiled), appendaged bacteria, and filamentous bacteria  Prosthecobacter dejongeii http://www.anselm.edu/homepage/jpitoc Coxiella burnetii https://microbewiki.kenyon.edu/index.php/P ch/genbios/labspecthumbnails.html rosthecobacter Bacteria Round Rod Between Spindle-like Shapes Curved Spiral Long, helically coiled Vibrio Spirillum Treponema pallidum 3 http://www.med66.com/new/201303/lt201303279095.shtml Wikipedia  Various arrangements of cocci Staphylococcus aureus Streptococcus pyogenes Wikipedia Staphyl: from Greek “staphylē” which means “bunch of grapes” Strepto: from Greek “streptos” which means “twisted”  Many variations on basic morphological types Morphology typically does not predict physiology, ecology, phylogeny, or other properties of a prokaryotic cell. May be selective forces involved in setting the morphology optimization for nutrient uptake (small cells and high surface-to-volume ratio, such as appendaged cells) swimming motility in viscous environments or near surfaces (helical or spiral- shaped cells) gliding motility (filamentous bacteria)  Most cultured rod-shaped bacteria are between 0.5 and 4.0 µm wide and 700 µm in diameter (Table 2.1) Size range for eukaryotic cells: 2 to >600 µm in diameter Table 2.1  Surface-to-volume ratios, growth rates, and evolution advantages to being small (Figure 2.3) more surface area relative to cell volume than large cells (i.e., higher S/V ratio). support greater nutrient and waste product exchange per unit cell volume tend to grow faster than larger cells rapid mutations lead to faster evolution  Lower limits of cell size Cellular organisms (with cell membranes)