3.4 Microbiology Flashcards
What is microbiology?
The branch of biology dealing with the structure, function, uses, and modes of existence of microscopic organisms
Microorganisms include Bacteria, Fungi, Viruses and Protoctista
Name 6 parts of bacteria
- Cell membrane
- Cell Wall (Peptidoglycan)
- Cytoplasm
- Ribosomes 70s
- Loose DNA
- Flagela
How does bacteria reproduce?
Asexually by binary fission
What are the names of the 3 classification of bacteria?
- Bacillus
- Coccus
- Spirillum
What shape is Bacillus?
0
Rod shaped
What shape is Coccus?
o
Spherical
What shape is Spirillum?
/\/\/ s
Corckscrew-shaped
What is lipopolysaccharides?
Mix of lipids and carbohydrates
What is peptidoglycan?
Mix of polysaccaride and polypeptides
carbohydartes and protein
Structure of Gram Positive bacteria?
- No lypopolysaccharide
- Thick Peptidoglycan
- Cell membrane
Colour of Gram Positive
Violet/Purple
Is Gram Positive affected by lysozome?
Yes
Is Gram Positive affected by penicilin?
Yes
Example of gram positive bacteria
Staphylococcus
Structure of Gram Negative bacteria
- Lipopolysacharide
- Thin peptidoglycan
- Cell membrane
Colour of Gram Negative baceria
Red
Is Gram Negative affected by lysozyme?
no
Is Gram Negative affected by penicilin?
No - resistant
Example of Gram Negative
Salmonella
After how many minutes does bacteria divide?
20 mins
What does microorganisms require for optimum growth?
- Nutrients - agar - carbon, minirals, salts and vitamins. Nitrogen is required to produce amino acids during protein synthesis
- Temperature - enzyme function
- pH - enzyme function
- Oxygen
What does bacteria need to respire?
Glucose
Obligate aerobes
Break down substrates using oxygen
Facultative anaerobes
Respire aerobically but can respire without oxygen
Obligate anaerobes
Respire without oxygen
Aseptic technique
apartus and equipment are kept free from micro organisms, are used to provent contamination of of bacterial cultures
Name the 3 methods of measuring bacterial growth
- Serial dilution technique
- Haemocytometer
- Turbidmetry
Serial dilution
is the stepwise dilution of a substance in solution. The dilution factor at each step is constant
Total count method
is the count of both live and dead bacteria
Viable count method
is the count of live bacterial colonies in a sample
Whats the asumption with bacteria?
1 cell divided asexually to provide a collony
Whats the 4 stages of bacterial growth curve
- Lag phase
- Log phase
- Stationary phase
- Death phase
Whats the Lag phase?
Slow population growth, (cells get used to surroundings), take in water, protein synthesis, DNA synthesis, enzyme production
Whats the Log phase?
Doubling of bacterial cells at each genoration time, optimum conditions, plenty of nutrience
What is the Stationary phase?
Death rate = production rate
Limiting factors - nutrients depletion
Whats the death phase?
Death rate exceeds production rate
Shortage of nutrience, lack of oxygen
Whats the shape of a bacterial growth curve?
S shape / Sigmoid
How to calculate how many colonies in a original sample
No. of colonies x dilution factor
