Microbiology Flashcards
flagellum function
for motility
pili
for attaching to surfaces and transferring plasmids by conjugation
plasmid
circular DNA which contains extra bacterial genes including genes for antibiotic resistance
where is the circular DNAs of prokaryotes found
in the nucleoid
by which process do prokaryotes reproduce
binary fission
the main function of the cell wall
other functions of the cell wall
*To prevent osmotic lysis
it supports the structure of the cell and provides rigidity to the cell
provides pressure inside the cell
what is a bacterial cell wall made of
peptidoglycan
what antibiotic is used instead of penicillin to combat gram-negative bacteria
vancomycin
physical requirements in which microbes thrive
optimal ph
optimal temperature
aerobic environments for some microbes
the optimal temperature for pathogens to grow(mesophiles)
37 degrees
at what temperature should bacteria be incubated, and for how long?
at 25 degrees and between 24-48 hours
which do we not completely seal the plate containing
to allow oxygen into the plate
why do we incubate bacteria at 25 degrees, and not completely seal the plate containing bacteria?
to ensure that the growth of pathogenic bacteria is low, as bacteria tend to grow rapidly at body temperature (37 degrees) and in anaerobic conditions
obligate aerobes
bacteria that require oxygen to replicate
obligate anaerobes
bacteria that can only survive and replicate in the absence of oxygen
facultative anaerobes
bacteria that are able to survive in the absence of oxygen but grow and divide faster in the presence of oxygen
in which two mediums can bacteria be grown
on liquid media like broth
on solid media containing agar
bacterium growth media usually contain a carbon source and a nitrogen source. true or false
true
in which form is the carbon source in a media usually in
in the form of glucose
the purposes of aseptic techniques
to prevent contamination of the environment by the microbes being handled
to prevent contamination of the microbial cultures by unwanted microbes from the environment
what are the purposes of the following aseptic techniques
1. Autoclaving all glassware at 121 degrees for 15 minutes
2. flaming loops and wires until red hot.
3. opening the petri dish lids at a small angle
4. roaring blue flame
5. keeping McCartney caps in hand and flaming the neck of the bottle
- kill bacteria and spores
- To kill bacteria
- to prevent bacteria from entering the dish
- to create a convection current to uplift air away from the cultures
- to not contaminate the desk and also to create a convection current to lift air from the broth
purpose of sterilizing materials during experiments
to grow pure cultures of microorganisms
how do we sterilize plastics like Petri dishes
by irradiating them
how do we sterilize the growth media
by heating it in an autoclave
autoclave
a pressure cooker that allows a pressure of 15 atm and a temperature of 121 degrees to be generated
the function of streak plates
can be used to separate mixed cultures into pure ones by separating out individual colonies which can then be used to inoculate fresh plates
to inoculate means
to introduce cells or organisms into a culture medium
state three problems encountered when trying to count bacteria(what are the solutions to these problems)
they are small (use a microscope or spread them onto agar and allow them to grow into a colony)
they are several of them (Dilute the sample)
it is difficult to determine whether they are alive or dead (allow them to grow into colonies)
