Introduction to Microbiology Flashcards
what is microbiology?
the study of microbes
what are the 6 subgroups of microbes
bacteria archaea algae fungi protozoa virus
what is koch postulates 1?
Causative micro-organism must be present in every case of disease, but absent from healthy organisms
what is koch postulates 2?
Suspected micro-organism must be isolated & grown in pure culture
what is koch postulates 3?
Cultured micro-organism should cause disease when introduced into a healthy host
what is koch postulates 4?
Same micro-organism must be isolated again from diseased host
What are simple stains
make bacteria visible by using a single basic dye
what are differential stains
gram stain
acid fast stain
show the difference
what are special stains
stain specific structures such as flagellum and endospores
What is gram staining
differentiates bacteria into two groups (gram + and -)
what is gram positive stained
purple and has thick wall
what is gram negative stained
pink and has a thin cell wall
what are the steps in gram staining
- apply crystal violet
- apply iodine mordant
- alcohol wash (decolorisation)
- apply safranin (counteraction)
what is liquid media (broth)
ideal for culturing large quantities
what is solid media (agar)
ideal for isolating pure cultures
what is defined synthetic media
exact pure chemical with exact composition known
what is complex media
extracts from natural materials (beef, blood)
precise chemicals composition unknown
what is basal media
- nutrient broth
- nutrient agar
what is enriched media
Contains all the necessary ingredients to grow better a desired bacteria but also a multitude of bacterial species (e.g. Tryptic Soy agar & Nutrient agar; blood agar; chocolate agar)
what is differential media
includes ingredients, such as chemical indicators, that produce observable differences between species of bacteria (e.g. Blood agar)
what is selective media
contains ingredients that inhibit growth of some bacteria, but enhance growth of target organism
