Bacteria cell structures Flashcards
define glycoalyx/ capsule
gel like layer that adheres to external surface of the cell wall
what is the composition of the glycocalyx/ capsule?
polysaccharide (sugar), proteins, or both (glycoprotein)
what is the glycocalyx/ capsule other functions?
- )capsules protect bacteria cells from dehydration during periods of drying
- )capsules create a sticky surface on bacteria cell causing cells to adhere to each other
- )capsules mediate adherence of bacteria to host tissue surface aiding bacteria to establish infection
- )capsules protect bacteria from phagocytosis or engulfment by phagocytic cells
define phagocytosis
cellular “eating”
can some white blood cells carry out phagocytosis?
YES
which bacteria is easier to phagocytize?
unencapsulated
what does the cell wall’s composition depend on?
the bacteria
define peptidoglycan
a complex polysaccharide found in the cell wall of most (not all) bacteria
what does peptidoglycan provide?
rigidity to help maintain cell shape
what are examples of atypical bacteria?
- )archaebacteria have a cell wall but lack peptidoglycan (considered the oldest living organism on earth)
- )mycoplasma bacteria do NOT have a cell wall (has no definitive shape)
what are the cell wall functions?
- )Determines the shape of the bacteria cell
- )Protects cell from osmotic or water pressure changes
- )Holds the cell together and represents the external boundary of the cell
what color is the stain of a gram positive bacteria cell wall stain?
purple
what color is the stain of a gram negative bacteria cell wall stain?
pink-red
what 3 things do gram positive cell wall consist of?
- )peptidoglycan layer is 25 nanometers (nm) many layers
- )teichoic acid creates links between peptidoglycan layer
- )NO outer extra membrane
what 3 things do gram negative cell wall consist of?
- )peptidoglycan layer is 3 nanometer (nm) single layer
- )NO teichoic acid because there is only 1 layer of peptidoglycan
- )outer membrane: lipopoly- saccharide(LPS) bilayer
LPS molecule creates __________ membrane
selective
LPD can be _______ to animal or human in high quantities
TOXIC
can LPS elicit and immune response to help create immunity for future encounters?
YES
LPS can make bacteria cell _____ sensitive to certain antibiotics
LESS
what effect does penicillin have on the cell wall?
interferes with peptidoglycan linkages
what is the peptidoglycan content for gram positive cell wall?
80%-90% of cell wall
what is the peptidoglycan content for gram negative cell wall?
2%-12% of cell wall