Microorganisms & Medical Microbiology Flashcards
bacteria
- prokaryotes: one-celled organisms w/ no nucleus or membrane-bound organelles
- ribosomes and genetic material are free floating in the cytoplasm
coccus
spherical shaped bacteria the can join together to make:
- diplococci (2 bacteria together)
- strepococci (chains)
- staphylococci (clusters)
bacillus
rod-shaped bacteria that can join together to form diplobacilli, streptobacilli (chains), etc
spirillum
spiral-shaped bacteria
Gram staining
- application of crystal violet and iodine, which create a complex that adheres to the outermost layer of bacteria
- can help determine what antibiotic will be effective
Gram positive
- outermost layer: thick peptidoglycan cell wall
- purple color when stained b/c the bacteria cell wall is dehydrated and traps stain inside
Gram negative
- outermost layer: thin and composed of lipids
- outer membrane is removed, second red dye (safranin) is used
- lighter, pink color
bacteria reproduce:
- asexually
- transformation (DNA from environment)
- transduction (injected by bacteriophage)
- conjugation (DNA transfer from F+)
viruses
- cannot reproduce without a host and are not considered living particles
- genetic material held in a protein capsid
- lack most organelles b/c they do not reproduce or maintain cellular functions
lytic cell
- when a virus infects a cell
- induces cell to reproduce viral DNA instead of its own
- eventually the cell will lyse and release viral DNA into he matrix, can infect a new cell
virulent
-viruses that replicate by the lytic cycle, killing their host cell
lawn
a plated culture
lysogenic cycle
- bacteriophage does not lyse its host, and become integrated into the bacterial genome as a provirus, lying dormant for awhile
- ex: HIV
- environmental cues can cause it to enter lytic cycle
latent infection
virus does not spread as quickly during the lysogenic phase
superinfection
-cells containing proviruses are normally resistant to further infection by similar phages
fungi
- heterotrophic, eukaryotic organisms, most of their organelles mimic human cells
- have cells walls that contain chitin
fungi reproduce:
- sexually: diploid cells, undergo meiosis to create 4 haploid spores
- asexually (fission): one organism divides into 2 daughter cells
spore production
-spores are more resilient to hostile conditions so it occurs when conditions are not favorable
parasites
-organisms that live off of and harm a host that receives no benefit from it
helminths
- parasitic worms (tapeworms, roundworms)
- injested via contaminated food or water
protozoa
-unicellular eukaryotes that have many different features, many cause diseases
nitrogen cycle
- plants produce waste and decompose, releasing ammonia and ammonium ions into the environment
- bacteria then break them down into nitrate and nitrite which can replenish plants or be converted to atmospheric nitrogen
carbon cycle
-microbes contribute to the transfer of carbon molecules thru the cycle via fermentation, catabolism, and anabolism
photosynthesis
-sunlight, water, and CO2 are utilized by chlorophyll cells are utilized to produce sugars, which serve as an energy source
transmission
-spread of disease from one host to another
direct contact
touching the contaminated person and spreading the disease thru physical contact
indirect contact
transmission via droplets, vectors, soil, food, or water
sterilization
- kills all pathogens
- extreme heat, radiation, or ethylene gas
disinfection
- kills some pathogens but not all microbes present
- microwaves, pasteurization, or alcohols
antiseptics
-kills pathogens on living tissue
active immunity
-experiencing an infection once gives the host a natural immunity and the host does not experience the disease as long as the memory cells remain
vaccine
- when a virus is involved, natural process may not be useful
- an attenuated (weakened) pathogen is injected that forms memory cells but not the disease
passive immunity
-immunity acquired thru direct transmission of antibodies from one source to another
antibacterials
-work on certain types of bacteria because of the structure of the bacteria or mechanism of action
bactericidal agents
-kill bacteria
bacteriostatic agents
- stop bacteria from dividing
- patient needs to have a functional immune system
resistance
-some bacteria have developed this to certain types of antimicrobials and are no longer effective
antivirals
- viruses are more difficult to treat because they are neither cells nor alive
- to destroy a virus you usually have to destroy the host cell it is in
- prevention of viruses is much more effective
antifungals
-many work by destroying cell walls to eliminate the infection and maintain the host cells
antiparasitics
-number of different mechanisms of action, but they destroy the parasite without damage to the host
broad-spectrum antimicrobial
- one that treats many different species of a microbe
- hospitals want to use antimicrobials specific to the microbe
