Microbiology Flashcards
What is microbiology
The study of microorganisms
Classification of microorganisms
Fungi
Bacteria
Viruses
Conditions needed for the growth of microorganisms
Food (saprophytic and parasitic) Oxygen (aerobic, anaerobic and facultative) Temperature Moisture Ph level Time
What are saprophytic microorganisms
They feed on non living matter eg decaying plants
What are parasitic microorganism
They feed on living matter eg animals/human
What are aerobic microorganisms
Require oxygen
What are anaerobic microorganisms
Don’t require oxygen
What are facultative microorganisms
Can grow with or without oxygen
Microorganisms grow on foods with what water activity
0.80 or higher
Thermophilic means
Very hot environment
Examples of saprophytic fungi
Mushrooms
Mould
Examples of parasitic fungi
Ring worm,
Athletes foot
Use of mould
Manufacture of food stuff eg. Cheese
Manufacture of medicine eg penicillin
Conditions needed for the growth of mould
Food (they’re saprophytic)
Oxygen (they’re aerobic so will grow on the surface of foods)
Temperature (mesophilic (medium), they slow down at lower temperatures and are destroyed at higher temperatures)
Moisture (humid is best)
Ph (slightly acidic)
Time (24-48 hours)
How many cells in a mould spore
1
Cycle of mould
Spore Grows hypha Once in right condition grows hyphae Hyphae all become intertwined into mycelium Hyphae grow upwards from mycelium
Does mould sexually or asexually reproduce
Both
Tow types of moulds
Phycomycetes
Ascomycetes
Example of large fungi
Mushrooms
Poisonous mushroom
Death cap
Alright mushroom
Truffle
Reproduction of mushrooms
Start as single spore Hyphae grow Mycelium form Hyphae bunch up and grow upwards into a stalk Cap forms at top Underside has gills When ripe, mushrooms release spores Spores are dispersed
Conditions needed for the growth of yeast
Food; saprophytic Oxygen; facultative Temperature; mesophilic Moisture Ph level; slightly acidic (4-6) Time
Reproduction of yeast name
Asexually
Budding
Explain budding
When conditions are favourable, parent cell develops bud
Nucleus splits in two and moves towards bud
One goes into bud
Cell wall develops
2 separate now
Many buds will produce
Advantages of fungi
Protein;alternative foods Edible Cheese production Antibiotics Bread and brewing Vitamin supplements
Disadvantages of fungi
Food spoilage
Poisonous
Human diseases
Animal disease
Conditions needed for growth of bacteria
Food: both saprophytic and parasitic
Oxygen: aerobic, anaerobic and facultative
Temperature:all 4
Moisture
Ph: 6-7 (extreme heats or ph inhibits growth)
Time (double every 20 mins)
How do bacteria reproduce
Binary fission
Explain binary fission
Cell elongates Nucleus splits in two Spread apart Wall forms Two new cells
Stages in bacteria growth
Lag phase
Log phase
Stationary phase
Decline phase
What happens in lag phase
Little growth of bacteria as they are adapting to their environment
What happens in log phase
Bacteria multiply quickly as are in ideal conditions
What happens in stationary phase
No increase in growth
Production of new bacteria is compensated for by death of other bacteria
Plateau
Reason for death: lack of food, space and oxygen causes competition
Decline phase
Greater amount dying than being produced.
Some survive by producing endospores
What are endospores
Tough, dormant cells that form around DNA of a bacterial cell to suirvue
How to endospores form
DNA duplicates
Endospore forms around one
Rest of cell disintegrates and endospore remains dormant
Reproduce by binary fission when in suitable conditions
Example of endotoxins
Salmonella
Example of exotoxins
Staphylococcus aureus
Shapes of bacteria
Coccus (round) eg pneumonia
Bacillus (rod) eg salmonella
Curved and spiral eg cholera
Gram positive stain
Purple
Gran negative stain
Pink
Two ways of classifying bacteria
Shape
Gram staining
Features of a gram positive cells
Thick cell wall
No flagella
Produces spores
Low resistance to antibiotics
Example of a gram positive
Streptococci
Gram negative features
2 thin layers
Flagella
No spore production
High resistance to antibiotics
Example of gram negative
E. coli
