CH2: Structure of Bacterial Cells Flashcards
3 bacterial groups by shape
cocci: round
bacilli: rods
spirochetes: spiral-shaped
pleomorphic
Bactria that are variable in shape (many-shaped)
The shape of a baterium is determined by its
rigid cell wall
Cocci in clusters
e.g., Staphylococcus
Cocci in chains
e.g., Streptococcus
cocci in pairs with pointed ends
e.g., Streptococcus pneumoniae
Cocci in pairs with kidney bean shape
e.g., Neisseria (two kidney beans kissing)
Bacilli with square ends
e.g., Bacillus
Bacilli with rounded ends
e.g., Selmonella
Bacilli club-shaped
e.g., Corynebacterium
Bacilli fusiform
e.g., Fusobaterium
Bacilli comma-shaped
e.g., Vibrio
Spirochetes, relaxed coil
e.g., Borrelia
Spirochetes, tightly coil
e.g., Treponema
diplococci
cocci occur in pairs
cocci occur in chains
streptococci
cocci occur in grapelike clusters
staphylococci
bacteria size range
0.2 to 5 micrometer
smallest bacteria
Mycoplasma
outermost component common to all bacteria, except Mycoplasma
cell wall (Mycoplasma species are bounded by a cell membrane, not a cell wall)
The bacterial cell wall is located external to the cytoplasmic membrane and is composed of
peptidoglycan
Comparison of cell walls of Gram-positive and Gram-negative bacteria
peptidoglycan
teichoic acids
Lipopolysaccharide (endotoxin)
peptidoglycan: G(+) thicker, multilayer; G(-) thinner, single layer
teichoic acids: only in G(+)
Lipopolysaccharide (endotoxin): only in G(-)
periplasmic space
space between outer membrane and inner cytoplasmic membrane in G(-)
bacteria; contains beta-lactamases
beta-lactamases
degrades penicillins and other beta-lactam drugs
_____ proteins in G(-) bacteria facilates the passage of small, hydrophilic molecules into the cell
porin
act as a channel to allow the entry of essential substances such as sugars, amino acids, vitamins, and metals as well as many antimicrobial drugs such as penicillins
the term peptidoglycan is derived from
the peptides and the sugars (glycan) that make up the molecule
peptidogly glycan chain
NAM and NAG
peptidoglycan structure
a glycan chain (NAM and NAG), a tetrapeptide chain , and a crosslink (peptide interbridge)
Synonyms for peptidoglycan
murein and mucopeptide
NAM
N-acetyl muramic acid
NAG
N-acetyl glucosamine
tetrapeptide
cosisting of both D- and L-amino acids
diaminopimelic acid, unique to bacterial cell walls
D-alanine, involved in the cross-links between the tetrapeptides and in the action of penicilline
