Lab A-D Flashcards
Liquid Medium
Referred to as broth to grow large number of bacteria in short period of time
Solid Medium
1-2% agar, its a polysaccharide extracted from seaweed and its utilize in two ways.
Slant: tubes with medium solidified in a test tube, angled for greater surface area and to store cultures for long period of time.
Plates: Petri dish contains agar used for isolating individual cells from culture. Uses inoculating loop to spread it across the agar surface.
Semi-Solid Medium
Low agar concentration, does not solidify. Its used for motility studies
Defined
All chemicals used are known, no yeast, animal, or plant tissue present.
Complex
Media contains some ingredients of unknown chemical composition. Contains peptones, meat extract, and yeast extract.
Selective Media
Designed to allow growth of certain organisms while preventing growth of others
Differential Media
Allows you to tell organisms apart based on their differing appearances on that medium.
Cell size
Measured in um
Bacillus
Gram positive, rod-shaped
Coccus
Spherical, ovoid, or round shape
Coccobacilli
Intermediate shape between cocci and bacilli, very short rods
Spirillum
Rigid spiral structure
Pleomorphic
Group of cells different in shape, size or colour
Ocular micrometer
Microscopes eye piece that has a rules scale to measure size of individual cells
Stage micrometer
Special slide containing a scale marked off in 10 um
Steps of gram staining
1) Make thin smear of bacteria in slide and air dry
2) Apply crystal violet (primary stain) rinse with water
3) Apply iodine and rinse with water
4) wash with ethanol for 5-10 sec
Apply safranin, rinse with water and blot dry
What is the role of crystal violet in gram staining?
Its the primary stain which enters the cell and stain everything in a non-discriminating fashion.
Role of Iodine in gram staining?
Its a mordant, enters cell and form a large crystal violet-iodine compound that get stuck in the pore of peptidoglycan
Role of ethanol in gram staining?
Washes away the lipids of gram negative cell walls and appears to make peptidoglycan more porous so CVI complex is washed out.
Role of Safranin in gram staining?
Pink counterstain which makes gram negative seen more
Aerobic
Organism that requires oxygen to grow
Obligate aerobes
Needs oxygen for growth dies without it
Facultative anaerobes
Use oxygen when it’s available, if no oxygen Will switch to metabolism that doesn’t need oxygen
Aerotolerant anaerobes
Doesn’t require oxygen to grow
Microaerophile
Requires oxygen but in low concentration
