Bacteria Flashcards
What are bacteria
They are microscopic
Single celled
They have a cell wall
Do not have a nucleus or membrane enclosed organelles
Single loop of DNA
What are the types(Shapes) of bacteria
Rod - Shaped e.g Tetanus, TB
Round- shaped e.g Pneumonia, Food poisoning
Spiral shaped e.g. syphilis collera
Explain Bacterial reproduction
Reproduce asexually by binary fission
DNA strand replicates itself
Cell elongated with DNA strand attached to each end
Cell splits to two simillar sized cells
Bacteria can reproduce every 20 minutes in suitable conditions
Short life cycle means that mutations e.g resistance to antibiotic spread fast
What are endospores
Endospores are tough walled spores capable of surviving harsh conditions
Form when a bacterial chromosome replicates
one of the new strands becomes included in an endospores inside the parent cell
The parent cell then breaks down and the endospores remains dormant
When conditions are suitable endospore absorbs water and tough wall breaks down
What is nutrition in bacteria
Autotrophic ( make their own food )
- photosynthetic (Use light as energy source to make food )
- Chemosynthetic ( Use chemical reactions as an energy source to make food)
Heterotrophic ( takes in food )
- saprophytic ( live on and take food from dead sources )
- parasitic ( take in food from a live host and usually cause harm to the host )
What factors affect bacterial growth
Temperature - affects bacterial activity by influencing rate of enzyme action
- most bacteria 20- 30 by disease causing bacteria prefer 37
Oxygen concentration - “Aerobic bacteria need oxygen for respiration .Aerobic bacteria do not require oxygen for respiration”
- obligate anerobes - must have oxygen for respiration
- Facultative anerobes - can respite with or without oxygen
Ph
- most bacteria prefer PH 7
External solute concentration
- environment outside a bacteria has a lower solute concentration than so water will pass in and out by osmosis
- if the environment has higher solute concentration water will pass ou they osmosis
- bacteria will not be able to grow and reproduce due to shortage of water
- basis of preserving foods by salting
Economic benefits of bacteria
Manufacture products like yogurt and cheese ( lactobacilli)
Use of genetically engineered bacteria to make insulin, drugs and enzymes
Economic disadvantages of bacteria
Cause human, plant and animal diseases
Cause food decay
What are pathogens
Pathogens are micro organisms that cause disease
What are antibiotics
“Antibiotics are chemicals made by fungi or bacteria to kill or stop the growth of bacteria”
Bacteria can develop immunity to antibiotics by mutations
Multi resistance bacteria have evolved that are not affected by most anti biotics
Describe bacterial growth
The lag phase - no increase in numbers
The log phase - numbers increase very rapidly
The stationary phase - no increase in numbers
The decline phase - rapid fall in numbers
The survival phase - some bacteria survive as spores
What is batch culture
A certain amount of nutrients is added to the micro organisms in the bioreactor
The bioreactor is closed
The bacteria go through the lag, log and stationary phases of growth
The process is stopped
The bioreactor is emptied and sterilized so the process can be repeated
Advantages: - simple process
- Allows small volume of product to form
What is continuous flow culture
Nutrients are continuously added to the bioreactor
Bioreactor is left open
Bacteria, culture medium and product are continuously removed
Bacteria are maintained at the log stage of growth
Conditions in the bioreactor are kept constant
Advantages
- productions is continuous ( No time wasted )
- productions is formed more rapidly ( bacteria very active in log phase )
