Chapter 1, 3 and 4

• Prokaryotic Cells


  a. genetic material not in membrane bound nucleus

  b. all are unicellular

  c. lack membrane-bound cell organelles

  d. usually binary fission
• Eukaryotic Cells


  a. genetic material in membrane-bound nucleus

  b. unicellular or multicellular

  c. contains numerous, specialize

  d cell organellesd. usually mitosis
• Bacterial Size


  -Most bacteria ranges from 0.2 to 4um in diameter

  -Smallest: mycoplasma (-0.1 um), Largest: Epulopiscium (-600 um)
• Coccus


  Round bacterial shape, examples: diplococci, streptococci

  
• Bacillus


  Rod-shaped bacterial cell, examples: diplobacilli, streptobacilli

  
• Spiral


  Bacterial shape with one or more twists, examples: vibrio, spirillum
• Monomorphic


  Bacteria with a single shape
• Pleomorphic


  Bacteria with multiple shapes
• Glycocalyx


  -Substances on the outside surface of the cells

  -thick, sticky polymers of polysaccharides and peptide
• Capsule


  -organized and firmly attached to cell wall

  -sometimes protect bacteria from phagocytosis
• Slime layer


  unorganized and loosely attached to cell wall
• Flagella


  -long appendage that propels bacteria

  - taxis - the movement towards or away from stimulus

  -allows for motility
• Fimbriae


  -Short hair like structures at the poles or covering the surface

  -a few to several hundred- allow them to stick to surfaces
• Pili


  -longer than fimbriae

  -only one or two per cell

  -motility or DNA transfer
• Basic information- The Cell wall

  a. most prokaryotes have

  b. surrounds cell, protects the interior of the cell from adverse changes in the outside env.

  c. complex, semi-rigid structure, maintains shape

  d. prevents bacterial cells from rupturing when water pressure is greater inside than out

  e. clinical relevance: it is where some antibiotics function, the composition helps to differentiate major bacterial types
• Peptidoglycan


  -repeating disaccharides of N- acetlyglucosamine and N- aceytlmuramic acid form back bone attached to polypeptide to form lattice like structure
• Gram Stain


  Differential staining method to classify bacteria based on cell wall composition
• gram positive cell walls

  a) thick layer of peptidoglycan

  b) the antibiotic penicillin prevents G+ growth=penicillin sensitive

  c) will stain purple with the gram stain
• gram negative


  a) thin layer of peptidoglycan

  b)has an outer membrane=makes G- penicillin resistant.= lipopolysaccharide is embedded in the outer membrane, part of this, lipidA, is released when G- bacteria die acts as toxin

  c)will stain red with the gram stain
• Atypical cell walls (not very common)

  a. no cell walls

  1) genus Mycoplasma

  2) Archaea: lack cells walls or have unusual walls
• Atypical cell walls (not very common)

  b. Acid Fast cell walls

  1) present in Mycobacterium

  2) high lipid content and are waxy> allows these bacteria to survive for weeks in dried sputum.

  3) stain red with the acid fast stain > will not take up dyes for gram stain
• Plasma Membrane (structure and function)

  Structure:

  1. selective permeability

  2. phospholipid bilayer

  Function:

  1. hydrophilic head & hydrophobic tails>amphipathic

  2.proteins embedded within to regulate what goes in/out
• simple diffusion


  movement q molecule from high concentration to an area of low concentration
• facilitated diffusion


  an integal membrane protein carries a molecule across from high concentration to an area of low concentration
• osmosis


  diffusion of water
• Nucleoid


  a. region where the DNA is located> single circular chromosome

  b. many bacteria also have extrachromosomal pieces of DNA > plasmids> often advantageous gene
• Ribosomes


  a. site of protein synthesis

  b. differ from eukaryote ribosomes (30S-50S= 70S)
• Inclusions


  - reserve deposits, cells accumulate nutrients when plentiful, use when deficient

  - Polysaccharide granulates, lipid inclusions
• Endospores


  a. specialized "resting" structures cells become when env conditions poor

  b. when conditions improve, endospore returns to the vegetative state(metabolically active)>withstand high heat, radiation, low water, toxic chemicals

  c. most common genera are Bacillus (B. anthracis) and Clostridium( C. tetani, C. difficile)
• The Archaea


  1. Live in habitats that are similar to the extremes

  2. Methanogens, hyperthermophiles, extreme halophiles, and sulfur reducers

  3. More closely related to Domain Eukarya than to Bacteria
• Differences from other cell types

  1. Certain genetic sequences are only found in their rRNA

  2. Unique method of DNA compaction

  3. Unique membrane lipids, and cell wall composition,
• Units of Measurements


  1. 1 μm = 10-6 m = 10-3 mm

  2. 1 nm = 10-9 m = 10-6 mm
• Micrometer


  Unit of measurement equal to 10^-6 meters
• Nanometer


  Unit of measurement equal to 10^-9 meters
• Light Microscopy


  Study using visible light to observe specimens
• Compound Light Microscopy


  Type of light microscopy using multiple lenses
• Darkfield


  Microscopy technique illuminating specimens against a dark background
• Phase Contrast


  Microscopy technique enhancing contrast of transparent specimens
• Electron Microscopy


  a. Transmission (TEM)-e-pass through specimen, 2D, internal structures

  b. Scanning (SEM)- e- reflected from the specimen, 3D, surface features
• Smear


  a thin film of a solution of microbes on a slide