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Definition: Microbiology
Study of microorganisms & their effects on the environ.
Definition: Epidemiology
Study of health & disease states in a population
Def: Intoxication
Ingestion of a toxic agent
Def: Infestation
an organism living on the body surface
Def: Infection
an organism transmitted to a host
Def: Immunology
Study of human body immune response mechanisms (immunity, allergy, transplantation, cancer, immune dysfxn)
Def: Infectious disease
Pathologic state produced by microorganisms living in/on human body;

Causes direct damage, nutrient competition, etc
organisms living together for the benefit of both
organisms living together at the expense of another
organism capable of causing detrimental effects in a normal host
Opportunistic pathogen
organism doesn't usually produce disease but can under certain circumstances
Carrier state
host harboring and transmitting potential pathogen
Environmental factors affecting human interaction w/ microorganisms
nutrients, oxygen, anti-microbial substances, physical barriers, pH, microenvironments
Sterile areas of the body
areas where microorganisms shouldn't be found;

Blood, lymph
non-sterile areas of body
most areas other than blood or lymph
Superkingdom: Eukaryote

animalia (kingdom)

parasitic worms, arthropods
fungi (kingdom)
includes: molds, yeast
branches of kingdom protista
Protozoa - protozoan parasites
Superkingdom: Prokaryotae

Monera - bacteria, rickettsia, chlamydia
evidence for endosymbiont origin of mitochondria
- eukaryote cells still have endosymbiotic bacteria
- ribosomes of mito more like those of prokaryotes
- mito have own DNA (circular, like prok.)
- mito control their own division
- gene expression into mito similar to prok.
- energy prod. in inner membrane, like prok.
- some antibiotics that kill bacteria also affect mito (chloramphenicol)
outer mitochondrial membrane origin
a reminant of its cell wall
inner mitochondrial membrane origin
equivalent to a euk. cell membrane
typical prokaryote structure
May contain:
  • capsule - locate external to cell wall)
  • ribosomes
  • cytoplasm
  • cell wall
  • plasma membrane
  • nuclear area (non-membrane bound DNA)
  • plasmids - circular DNA
  • flagella
  • fimbriae - hair-like projections
  • plasma membrane
  • inclusions
selective toxicity
if you can find something poisonous to a prokaryote but not a euk. (or vice versa), you can limit infection
Clinical significance of prok. cell structure
- selective toxicity
- interfere w/ prok. cell structure to limit growth
- basis of antibiotic therapy
Structure/Fxn of Viruses
Structure: protective protein coat (capsid) surrounding genetic info (DNA or RNA, not both for same virus);

Requires host cell for replication;

Genetic info encodes for:
- replication enzymes/mechanism
- redirection of cellular fxn
- replication of protein coat
- replication of viral nucleic a.
infection/replication process of viruses
1. introduction of infecting virus
2. Attachment: virus attaches to receptor on host cell

- can only infect cells whose receptors will recognize attachement point on viruses capsid or envelope
3. Penetration: virus is introduced into host cell
4. Uncoating: capsid is shed
5. Replication: synth of viral mRNA, synth of viral protein for new capsid, synth of viral nucleic acid
6. Assembly: capsid form around DNA/RNA
7. Release: by budding (forms envelope) or cytosis (no envelope)
8. Virus infects another host cell
pathogenesis of viruses
Cause direct cellular damage (do not create toxic substances);

cause disfunction of host cell;

may cause immunological damage to infected host cell
non-enveloped DNA viruses
contain no external envelope;

ex. parvovirus, adenovirus
enveloped DNA viruses
contain DNA surrounded by a capsid & envelope;

ex. herpes virus, poxvirus
non-enveloped RNA viruses
RNA surrounded by a capsid only (no envelope);

ex. poliovirus, rotavirus
enveloped RNA viruses
RNA surrounded by capsid & envelope;

ex. retrovirus (HIV), paramyxovirus
resolving power
ability to differentiate 2 closely positioned points
effect of wavelength on resolving power
shorter wavelength = greater resolving power
dark field microscopy
visible light introduced @ an angle so only light refracted by specimen enters lens;

organism appears white agains a black field;

generally only used for treponema pallidum (syphillus)
bright field microscopy
visible light wavelengths;

organism dark against white-grey field

stains: simple, gram stain, negative stain
Phase-contrast/Nomarski interference microscopy
visible light introduced thru specimen out of phase or non-parallel;

variations in density of cell materials refract light differently
UV light / flourescent microscopy
use short wavelengths to improve RP and increase mag.;

use flourescent dyes that flouresce in specific WL of visible light
Transmission electron microscope
streams of electrons focused by electromagnets;

significant improvement in RP and mag;

requires lots of prep
scanning electron micro.
streams of electrons bounced of surface
- noncellular
- require host to replicate
- some have envelope
- virtually no self-contained enzymes (use host)
- reproduce by molecular replication
- variety of effects to host
- only grown in specific living cell
bacteria (eubacteria)
- prok. cell structure
- free-living as single of small group of cells
- some produce resistant endospores
- reprod. by sexual binary fission
- produce toxic substances
- can be grown in lab
- prok. cell structure
- free-living (but capable of surviving in WBC)
- waxy material in cell wall make them resistant
- slow reprod. by binary fission
- do not produce toxic substances
- trigger immunologic damage in host
- slow growth in lab
rickettsia and chlamydia
- prok. cell structure
- obligate intracellular parasites
- dependent on host cell
- poor survival outside host
- transmitted by arthropod vector
- do not grow in lab
- prok. cell structure
- lack bacterial cell wall
- reprod. by binary fission
- have sterols in cell mem.
- poor survival in environment
- produce inflamatory rxn in host
- can grow slowly in enriched lab media
- euk. cell structure
- free-living cells grow as single cells (yeast) or chains (molds)
- chitinous cell wall
- reprod. by budding/apical growth of filaments
- few pathogens
- generally don't prod. toxic substances
- may prod. asexual spores
- grown in lab as colonies or mycelia
- euk cell structure
- lack cell wall but animal cell type of mem.
- free-living or intracellular parasites
- single cell organisms
- complex life cycles
- some transmitted by insects
- cannot be grown in lab
- euk cell structure
- multi-cell animal parasites
- flatworms & roundworms
- environmentally resistant ova
- compete for nutrients w/ host
- complex life cycle w/ sexual stages
- not grown in labs
- euk cell structure
- ectoparasites (blood sucking)
- some transmit infectious viruses, bact., etc
- produce immunological damage
- produce toxic substances
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