biology of infectious diseases Flashcards
define a pathogenic microorganism
a pathogen is an organism with the potential to cause disease
what is a pathogen’s survival dependent upon?
- its capacity to replicate & persist on or within another species
what is a primary pathogen & its virulence?
- cause disease in an otherwise normal or healthy individual
- highly virulent
what are opportunistic pathogens?
- cause infectious disease in a compromised host that would not typically occur in a healthy host
what is a secondary invader?
- an invader that occurs after a primary invader
what shape is a coccus bacteria?
spherical shape
what shape is a bacillus bacteria?
rod (longer than they are wide)
what are the 3 types of flagellum structures?
A. Spirillum - flagella between cell wall & plasma membrane
B. Spirochete - endoflagellum (flagella inside)
C. Filamentous - mass of filamentus structure
name the components of the bacteria ultrastructure
- cytoplasm (gel-like matrix, contains cell structures)
- cell envelope (outer capsule overlying the plasma membrane)
- plasma membrane
- bacterial cell wall
- glycocalyx
- flagella (occur in both gram +ve & -ve)
- pili (occur almost exclusively in gram -ves)
what is the function of the bacteria cytoplasm
- cell growth, metabolism, replication
- as it contains cell structures (chromosome, ribosomes)
what are plasmids?
- small circular DNA
- capable of autonomous replication
- can be transferred from cell to cell during binary fission or through conjunction
- contain genes for antibiotic resistance & exotoxin production
what is the function of the bacteria plasma membrane?
- regulates movement of material into & out of cell
- synthesis of cell wall components
- contains base of flagella
- secretes proteins
what is the function of the bacteria cell wall made of peptidoglycan?
- determines cell shape
- protects cell from environment
- prevents lysis or collapsing due to changing osmotic pressure
- anchors appendages
compare gram positive & gram negative bacteria?
gram +ve
- thick cell wall with a regular structure
- retains crystal violet & stains purple
gram -ve
- thin cell wall that is bound by an outer membrane of lipopolysaccharide (Lipid A endotoxin + core polysaccharide + O-Antigen)
- does not take up the crystal violet & stains red from counterstain
what are the functions of the glycocalyx in both gram +ve & -ve bacteria?
- protects bacteria from desiccation
- helps bacteria resist phagocytosis
- facilitates bacteria attachment & allows production of biofilms
