Micro-organisms Flashcards
What are micro-organisms?
Living organisms that aren’t directly visible to the unaided eye.
What are the 3 types of micro-organisms?
- Bio (life)
- Micro (small)
- Logy (study of)
Where are micro-organisms found?
Air, soil, water, animals, human body.
Where are micro-organisms found?
Air, soil, water, animals, human body.
What is the definition of bacteria?
Microscopic, single celled organism.
What do bacteria need for growth?
Moisture
What can bacteria cause?
Food-bourne illnesses.
What are the 3 basic shapes of bacteria?
- Bacillus (rod)
- Coccus (spherical)
- Spiral (spirullum)
What is the function of bacteria?
Form structures (Spores) to protect themselves from adverse conditions.
What happens when conditions are favourable?
They burst out, grow and multiply through Binary Fission.
What is Fungi?
Single-celled organism, seen as only individual cells under microscope.
Do fungi require more/less moisture?
Less due to being able to grow in acidic environments.
Do fungi form spores?
Some can but overall they are less resistant.
Do fungi grow quicker/slower?
Slower but very adaptable.
What are the fungi groups?
- Zygomycetes
- Ascomycetes
- Basidiomycetes
- Deutromycetes
What is it called when cocci remain in pairs?
Diploccoci
What is it called when cocci remain in chains?
Streptococci
What is it called when cocci that have divided into pairs and remain in groups of 4?
Tetrads
What shape do bacilli mainly appear as?
single rods known as Diplobacci
What shape do sprial have usually?
Curved rods known as Vibrios.
What is the definition of growth?
Process by which micro-organisms synthesise vital cell components.
What are the vital cell components that are synthesised?
- Cell wall material
- Cytoplasmic material
- Genetic material
What is generation time?
The time it takes for the population of bacteria to double in numbers.
What are the 4 different growth phases of bacteria?
- Lag phase
- Log phase
- Stationary phase
- Death phase
What happens in the Lag phase?
- Bacteria introduced into environment - checking surroundings
- Cells are very active metabolically
- Some cells change very little
- 1 hour - 7 days
What happens in the log phase?
- Rapid cell growth
- Populations double every generation
- Microbes = sensitive to adverse conditions
What happens during the stationary phase?
- Death rate = rate of production
2. Cells start to encounter environmental stress
What happens in the death phase?
- Death rate greater than rate of reproduction
2. Populations begin to die
What are some of the intrinsic factors that affect growth of bacteria?
- pH
- Moisture
- Nutrient content
What are some of the extrinsic factors that affect growth of bacteria?
- Temperature
- Relative humidity
- Gaseous environment
What pH can no pathogen grow under?
pH of below 4.6
