Chapter 4 - Microbiology. Flashcards
1
Q
What is a gram stain?
A
A method of staining the cell walls of bacteria as an aid to their identification.
2
Q
What is a Gram+’s cell wall made out of?
A
Peptidoglycan.
3
Q
What does a Gram-‘s cell wall have that a Gram+’s doesn’t?
A
A layer of Lipopolysaccharide.
4
Q
What dye’s are used for Gram staining experiments?
A
- Crystal Violet binds to the peptidoglycan binding Gram+ bacteria purple.
- The counterstain Safranin stains the Gram- bacteria red.
5
Q
How do bacteria divide?
A
Binary fission.
6
Q
What condition do bacteria need to grow?
A
- Nutrients.
- Growth factors (vitamins and minerals).
- Correct temperature/pH.
- Oxygen (Apart from obligate anaerobes).
7
Q
What are the 3 types of Bacteria (classified by their oxygen requirements).
A
- Obligate aerobes (require oxygen for metabolism).
- Facultative anaerobes (Grow best in the presence of oxygen but can survive in its absence).
- Obligate anaerobes (Can’t grow in the presence of oxygen).
8
Q
How can the population of micro-organisms be measured?
A
- Directly - Viable counts or total counts.
- Indirectly (E.g. Measuring turbidity)
9
Q
What is a colony?
A
A cluster of cells, or clone, which arises from a single bacterium or fungal spore by asexual reproduction.
