Microbiology (BIO-104) – BCC Lecture Exam #1 Study Guide with Key
Concepts and Practice Questions
Shapes of bacteria - ANS✔✔ cocci, bacilli, spirilla
Average size of bacteria - ANS✔✔ 0.2 to 2.0 µm diameter - 2 to 8 µm length
Variations of spiral bacteria - ANS✔✔ Vibrio [Curved Rod], Spirilli [Helical/Rigid], Spirochete
[Helical/Flexible]
Arrangements of bacteria - ANS✔✔ Pairs: diplococci, diplobacilli
Clusters: staphylococci
Chains: streptococci, streptobacilli
Groups of four: tetrads
Cubelike groups of eight: sarcinae
Glycocalyx - ANS✔✔ External to the cell wall
Viscous and gelatinous polymer
Made of polysaccharide and/or polypeptide
Type 1: Capsule: neatly organized and firmly attached [prevent phagocytosis]
Type 2: Slime layer: unorganized and loose
Flagella - ANS✔✔ Filamentous appendages external of the cell
Rotate like a propeller on prokaryotes, enabling movement.
Made of protein flagellin Three Parts:
Filament: Outermost region
,Hook: attaches to the filament.
Basal Body: consists of rod and pairs of rings; anchors flagellum to the cell wall and membrane
Flagella Facts - ANS✔✔ Bacteria without flagella are called atrichous
Flagella allow bacteria to move toward or away from stimuli (taxis)
Flagella rotate to "run" or "tumble"
Flagella proteins are called H antigens and distinguish among serovars (e.g., Escherichia coli
O157:H7) which are associated with food borne epidemics
Axial Filaments - ANS✔✔ Also called endoflagella
Found in spirochetes
Anchored at one end of a cell
Rotation causes cell to move like a corkscrew
peptidoglycan - ANS✔✔ key component in the cell walls of bacteria, forms a complex network
cross-linked with peptide bonds, found only in bacteria
Gram postive cell wall - ANS✔✔ Teichoic acids Lipoteichoic acid links cell wall to plasma
membrane
Wall teichoic acid links the peptidoglycan
Carry a negative charge
Regulate movement of cations
Polysaccharides and teichoic acids provide antigenic specificity
Gram Negative Cell Walls - ANS✔✔ Periplasm between the outer membrane and the plasma
membrane contains peptidoglycan
Outer membrane made of polysaccharides, lipoproteins, and phospholipids
, gram negative cell wall facts - ANS✔✔ Protect from phagocytes, complement, and antibiotics
**Made of lipopolysaccharide (LPS) O polysaccharide functions as antigen (e.g., E. coli O157:H7)
Lipid A is an endotoxin embedded in the top layer
Porins (proteins) form channels through membrane
Gram stain - ANS✔✔ A method for the differential staining of bacteria that involves fixing the
bacterial cells to a slide and staining with crystal violet and iodine, then washing with alcohol,
and counterstaining with safranin. Results in gram-positive bacteria retaining the purple dye and
gram-negative organisms having it decolorized so that the red counterstain shows up.
acid fast bacteria - ANS✔✔ Retain the primary stain even when treated with acid alcohol. Cell
walls contain mycolic acid. Includes Mycobacterium and Nocardia species which include human
pathogens as M. tuberculosis and M. Leprae.
Antimicrobial drugs - ANS✔✔ Cell wall synthesis is the target for some antimicrobial drugs
because they may damage the bacterial cell wall without harming the cells of the animal host.
Lysozyme hydrolyzes bonds in peptidoglycan
Penicillin inhibits peptide bridges in peptidoglycan
The Plasma (Cytoplasmic) Membrane - ANS✔✔ Internal to cell wall
Phospholipid bilayer that encloses the cytoplasm
Peripheral proteins on the membrane surface
Integral and transmembrane proteins penetrate the membrane
Movement of Materials across Membranes - ANS✔✔ Passive processes: Simple/facilitated
diffusion, osmosis.
Active transport: requires a transporter protein and ATP.
Concepts and Practice Questions
Shapes of bacteria - ANS✔✔ cocci, bacilli, spirilla
Average size of bacteria - ANS✔✔ 0.2 to 2.0 µm diameter - 2 to 8 µm length
Variations of spiral bacteria - ANS✔✔ Vibrio [Curved Rod], Spirilli [Helical/Rigid], Spirochete
[Helical/Flexible]
Arrangements of bacteria - ANS✔✔ Pairs: diplococci, diplobacilli
Clusters: staphylococci
Chains: streptococci, streptobacilli
Groups of four: tetrads
Cubelike groups of eight: sarcinae
Glycocalyx - ANS✔✔ External to the cell wall
Viscous and gelatinous polymer
Made of polysaccharide and/or polypeptide
Type 1: Capsule: neatly organized and firmly attached [prevent phagocytosis]
Type 2: Slime layer: unorganized and loose
Flagella - ANS✔✔ Filamentous appendages external of the cell
Rotate like a propeller on prokaryotes, enabling movement.
Made of protein flagellin Three Parts:
Filament: Outermost region
,Hook: attaches to the filament.
Basal Body: consists of rod and pairs of rings; anchors flagellum to the cell wall and membrane
Flagella Facts - ANS✔✔ Bacteria without flagella are called atrichous
Flagella allow bacteria to move toward or away from stimuli (taxis)
Flagella rotate to "run" or "tumble"
Flagella proteins are called H antigens and distinguish among serovars (e.g., Escherichia coli
O157:H7) which are associated with food borne epidemics
Axial Filaments - ANS✔✔ Also called endoflagella
Found in spirochetes
Anchored at one end of a cell
Rotation causes cell to move like a corkscrew
peptidoglycan - ANS✔✔ key component in the cell walls of bacteria, forms a complex network
cross-linked with peptide bonds, found only in bacteria
Gram postive cell wall - ANS✔✔ Teichoic acids Lipoteichoic acid links cell wall to plasma
membrane
Wall teichoic acid links the peptidoglycan
Carry a negative charge
Regulate movement of cations
Polysaccharides and teichoic acids provide antigenic specificity
Gram Negative Cell Walls - ANS✔✔ Periplasm between the outer membrane and the plasma
membrane contains peptidoglycan
Outer membrane made of polysaccharides, lipoproteins, and phospholipids
, gram negative cell wall facts - ANS✔✔ Protect from phagocytes, complement, and antibiotics
**Made of lipopolysaccharide (LPS) O polysaccharide functions as antigen (e.g., E. coli O157:H7)
Lipid A is an endotoxin embedded in the top layer
Porins (proteins) form channels through membrane
Gram stain - ANS✔✔ A method for the differential staining of bacteria that involves fixing the
bacterial cells to a slide and staining with crystal violet and iodine, then washing with alcohol,
and counterstaining with safranin. Results in gram-positive bacteria retaining the purple dye and
gram-negative organisms having it decolorized so that the red counterstain shows up.
acid fast bacteria - ANS✔✔ Retain the primary stain even when treated with acid alcohol. Cell
walls contain mycolic acid. Includes Mycobacterium and Nocardia species which include human
pathogens as M. tuberculosis and M. Leprae.
Antimicrobial drugs - ANS✔✔ Cell wall synthesis is the target for some antimicrobial drugs
because they may damage the bacterial cell wall without harming the cells of the animal host.
Lysozyme hydrolyzes bonds in peptidoglycan
Penicillin inhibits peptide bridges in peptidoglycan
The Plasma (Cytoplasmic) Membrane - ANS✔✔ Internal to cell wall
Phospholipid bilayer that encloses the cytoplasm
Peripheral proteins on the membrane surface
Integral and transmembrane proteins penetrate the membrane
Movement of Materials across Membranes - ANS✔✔ Passive processes: Simple/facilitated
diffusion, osmosis.
Active transport: requires a transporter protein and ATP.
