Monera Flashcards
Explain how bacteria are divided into groups by shape
- Spherical
- Rods
- Spirals
Describe the structure of bacterial cells
Always present-
1. Surrounded by cell wall
2. Cell membrane surrounds cytoplasm
3.there are no membrane bound organelles within the cell, in the cytoplasm there is ribosomes, numerous storage granuales + singular circular chromosome of DNA
Sometimes present-
1.outside the wall there may be further protection in the form of a semi solid capsule or slime liquid layer
2. Motile bacteria have flagella
3. Many bacteria also contain other circular pieces of DNA called plasmids which carry the gene for drug resistance
Describe the reproduction of bacteria
Bacteria reproduce asexually by a method called binary fission. 1.The chromosome is replicated
2. The cell elongates with a chromosome attached to each end( cell membrane)
3. The cell is divided down the middle and forms two equal sized cells
Describe how endospores form in bacteria and their function
Endospores help bacteria withstand harsh an unfavourable conditions.
1. The bacterial chromosome replicates
2. One of the new chromosomes ( DNA strand) becomes enclosed by a tough outer coat within the original cell producing an endospore
3. The parent cell then breaks down
4. These spores remain dormant resiting dessication and high temperatures
5. When favourable conditions return the endospore absorbs water and the tough outer wall breaks down
6. The new bacterium will divide by binary fission
Define the term antibiotics
Are chemicals produced by micro organisms that stop the growth of, or kill, other micro organisms without damaging human tissue
Describe how antibiotic resistance works
• When a patient is given an antibiotic, all the bacteria in that person are killed.
If antibiotic-resistant bacteria are present, they will not be killed.They will quickly colonise the patient.
When a disease-causing bacterium arrives, it can pick up the antibiotic resistance and the antibiotic will not affect it.
Antibiotic resistance is spreading in disease-causing bacteria.
Give example of potential abuse of antibiotics in medicine
The overuse of antibiotics in medicine results in the increased growth of antibiotic-resistant bacteria (because they have no competition). This happens when doctors prescribe antibiotics unnecessarily (e.g. for virus infections).
• The failure of some patients to complete their treatment of antibiotics allows the bacteria to survive and re-grow. This leads to the need for more antibiotics (along with the increased risk of the growth of resistant bacteria).
Describe the nutrition of bacteria
They get there food in four different ways grouped under the headings autotrophic or hetertrophic . Bacteria can be either autotrophic or hetertrophic.
Define autotrophic and it’s two methods photosynthetic and chemosynthetic
Autotrophic- means an organism makes its own food
Photosynthetic Bacteria- Bacteria that use sunlight to make their own food
Chemosynthetic Bacteria- Bacteria that use energy released by a chemical reaction to make food.
Define hetertrophic and it’s two methods Saprophytes and parasites
Hetertrophic- means an organism takes in food made by other organisms
Saprophytes- are organisms that take in food from dead organic matter
Parasites- are organisms that take in food from a live host.
Define the term symbiotic Bacteria and name + explain three types of symbiotic relationships
Symbiotic Bacteria- are organisms of one species that live in a close relationship with a second species where at least one organism benefits
There are three types of symbiotic relationships:
Both organisms may benefit (mutualism).
One organism benefits but does not harm its host (commensalism).
One organism benefits and harms its host (parasitism).
List the factors that affect bacterial growth
- Oxygen
- Temperature
- PH
- External solute concentrations
- Pressure
How does oxygen concentration affect the growth of bacteria
Aerobic Bacteria- Require oxygen for respiration. Most bacteria are aerobic. Eg. Streptococcus.
Anaerobic Bacteria- Do not require much oxygen. Eg. Clostridium.
Facultative Anaerobes- Can respire with or without oxygen. Eg. E-coli.
Obligate Anaerobes- Can only respire in the absence of oxygen. Eg. Bacteria causing tetanus.
How does temperature affect the growth of bacteria
Because each type of bacteria will have its own specific enzymes.
1. Most grown in temp range 10-30ºc.
2.some grow better at high temps
3. Low temps slow down the rate of bacterial growth
How does PH affect the growth of bacteria
Bacterial enzymes function best at a specific PH
1. Most live in the PH range 6-8
2. Some bacteria can tolerate very low( acidic) pr very high ( alkaline) PH values
How does external solute concentration affect bacteria growth
If the external solution has a higher solute (e.q. salt or sugar) concentration than the bacterial cytoplasm, water will move out of the bacteria. This dehydrates the bacteria and stops their enzymes from working. This is the principle behind the methods of food preservation such as salting and sugaring (as used for bacon and marmalade or jam).
If the external solution has a lower solute (e.q. salt or sugar) concentration than the bacterial cytoplasm, water will enter the bacteria. The cell walls of bacteria can normally prevent bacterial cells from bursting in these circumstances. Most bacteria live in less concentrated solutions
How does pressure affect bacterial growth
Limited by high pressure because cell wall is not strong enough
List the economic benefits of bacteria
1.( lactobacillus spp) Can produce cheese and yogurt from milk
2. ( streptomyces spp)Can produce antibiotics e.g penicillin
3. Genetically modified bacteria are used to make insulin, drugs, enzymes , amino acids, vitamins, alcohol
What are the economic disadvantages of bacteria
- Cause food to decay
- Cause human, animal and plant disease such as ( salmonella typhi)- Cause typhoid, ( vibrio cholera)- Cause cholera , ( mycobacterium tuberculosis) - Cause TB
Define the term sterile
A substance is sterile if it is free from all microbes
How can sterility be achieved
Sterility can be achieved by keeping material in damp heat( steam at 120ºc for 20 minutes. This is also known as autoclaving. This will kill all microbes and spores
Name the five stages of growth on the bacteria growth curve
- Lag phase
- Log ( exponential) phase
- Stationary phase
4.death or decline phase - Survival phase
Explain what happens in the lag phase
. Little or no increase in numbers
.Settling in phase
. Bacteria are adapting to their environment
Explain what happens in the Log phase
. Huge increase in numbers
. Exponential growth
.Numbers doubling by binary fission in every new generation
. Ideal conditions present e.g food , oxygen, space ect
Explain what happens in the stationary phase
. No increase or decrease in numbers
. Growth slows down due to: lack of food, space, moisture and oxygen
Explain what happens in the decline phase
. Numbers start to decrease
. Death rate is greater than reproductive rate
. Cause again by lack of food, space oxygen ect
Explain what happens in the survival phase
. Not all bacteria die
. Some may survive as spores( only rod shaped bacteria)
. Spores can survive by remaining dormant until conditions are suitable again
Define the term pathogens
Are micro organisms that cause disease
Explain in detail what happens in the bioprocessing continuos flow method
Continous Flow- involves maintaining the microbes in the log phase of growth by the addition of fresh medium.
- produces single-celled proteins
1. Large bioreactor full of medium + microbes is set up
2. When microbe in log phase, fresh, sterile medium is introduced at the top
3. A continuous flow of old medium with SCPs is removed from bottom
Explain in detail what happens in the bioprocessing batch method
Batch Culture- is when a fixed amount of nutrients and culture are added to a bioreactor. The bioreactor is emptied at the end of production.
- antibiotic stretomycin produced by batch method
- Bioreactor filled with fixed amount nutrients + stretomyces culture
- Bacteria go through all phases
- Liquid removed & filtered( product separated from solution) extracting the streptomyces culture
4.stretomycin separated out of remaining fluid.
