Microbiolgy Flashcards
1
Q
Why are bacteria important organisms?
A
- they spoil food
- food production e.g cheese/yoghurt
- nutrients recycling
- cause disease
2
Q
Which kingdom does bacteria belong too?
A
• prokaryotes
3
Q
What features do prokaryote posses?
A
- divide by binary fission
- no membrane bound organelles
- circular DNA
- peptidoglycan cell wall
- me some site of respiration
4
Q
How do you classify bacteria?
A
- Bacillus - Rod Shaped
- Coccus - Spherical
- Spirillium - Corkscrew
5
Q
What is Gram Staining used for?
A
• to distinguish between two types of bacteria , Gram positive and Gram negative
6
Q
Why do the two categories of bacteria have different properties?
A
• because of the differences in their cell wall
7
Q
What does the cell wall consist of?
A
• mixture of polypeptides/ polysaccharides known as peptidoglycan - they are cross linked
8
Q
What does the cross link in the wall provide?
A
- strength
- gives cell it’s shape
- protests against bursting
9
Q
How does Gram stain works?
A
- Initially all bacterial cells are colourless
- Slide of bacteria is flooded with crystal violet
- All bacteria absorb stain then fixed w/ Grams iodine before being discolourised w/ alcohol ( ethanol )
- Gram + retain crystal violet bc of their thick peptidoglycan cell wall, Gram - don’t bc peptidoglycan cell wall is thicker and outer layer contains lipopolysaccahride
- Counterstaining w/ red stain phenol fushinin causes Gram - bacteria to absorb and become red
- Gram + remain purple in colour
10
Q
What do microorganisms include?
A
- protoctista
- fungi
- virus
- prokaryote
