monera Flashcards
Cell wall
shape & structure. Made of sugars and proteins. Prevent cell taking in too much liquid when surrounded by less concentrated solution.
Cell membrane
holds all cell contents, controls what enters and leaves the cell. Semi-permeable, lipo-protein layer.
Cytoplasm
contains ribosomes and storage
granules but no mitochondria or
chloroplasts.
Flagellum
for movement.
Capsule
a semi-solid layer of mucilage that protects.
Nuclear material
DNA material
What are the shapes of bacteria
- Spherical (cocci)
- Rod (bacillus)
- Spiral (spirillum)
What is binary fission
A reproduction method which is a fast replication of cells. This means all daughter cells are identical
Explain binary fission
The chromosome attaches to the plasma membrane and the DNA is replicated The cell elongates and the two chromosomes separate The cell wall grows to divide the cell into two two identical daughter cells are formed
Endospore formation
A way that bacteria can withstand unfavorable conditions
Explain endospore formation
These are formed when the bacterial chromosome replicates The parent cell then breaks down and the endospore remains dormant One of the new strands becomes enclosed in a tough-walled capsule called an endospore The parent cell then breaks down and the endospore remains dormant When conditions are favourable the spores absorb water, break their walls and reproduce by binary fission
Autotrophic bacteria
Make their own food
Photosynthetic bacteria
Use light energy to make food
Called producers
E.g. purple sulphur bacteria
Chemosynthetic bacteria
Use energy from chemical reactions to make food
E.g. Nitrifying bacteria that convert ammonia to nitrates in the nitrogen cycle
Heterotrophic
Feed on other organisms
3 types of heterotrophic bacteria
Soprophytes
Parasites
Symbiotes
Soprophytes
Feed on dead matter causing it to breakdown and this allows nutrients to be recycle.
Parasites
Live on or in a host and take nutrients from it but the host is harmed in the process.
Symbiotes
Live in close union with other organisms to each other’s benefit. E.g. symbiotic bacteria in the human intestine
Factors affecting growth of bacteria
Temperature
Oxygen concentration
pH
External solute concentrat
Pressure
Temperature
Most grow between 20°C to 30°C
Low temperatures = slow growth
Some can tolerate higher temperatures without their enzymes becoming denatured
Ph
Most live at 7-8 ph (alkaline)
Few can tolerate acidic/very alkaline conditions
Not suitable ph =enzymes denatured
Oxygen
For respiration (aerobic bacteria)
Facultative anaerobes can respire with or without oxygen
Obligate anaerobes can only respire in the absence of oxygen
External solute concentration
Osmosis.
If external solution is more concentrated water will move out of the bacteria(dehydration)
If external solution is less concentrated water will enter the bacteria
Pressure
The growth of bacteria is inhibited by high pressures
Beneficial bacteria
Lactobacillus converts milk to yoghurt and cheese
Antibiotics can be formed by some microorganisms
Harmful bacteria
Pathogenic Bacteria can cause diseases in humans and animals.
Pathogenic Bacteria can cause diseases in plants.
Pathogenic
Micro-organisims that cause diseases
Antibiotics uses
Control bacteria and fungal infections without affecting the virus
Abuse of antibiotics
Increase growth of antibiotic resistant bacteria
Mutation in bacteria
Causes bacteria to develop antibiotic resistance
Growth curve bacteria
The lag phase
The log phase
The stationary phase
Decline phase
Death or survival phase
Lag phase
‘Settling In’ phase, bacteria adjust to their new environment.
Log phase
Also known as exponential phase, bacteria begin to divide very rapidly.
The stationary phase
There is no increase or decrease in numbers. The no. dead equals the no. created.
Decline phase
Numbers drop because there is increased competition for food, space and oxygen. There is a buildup of toxins and waste in the environment.
Death or survival phase
Not all bacteria die, some may survive in spores until good conditions return
Batch culture
The bacteria in the bioreactor go through the lag, log and stationary phases but stopped before the decline phase. The contents of the bioreactor are then removed and separated.
Continues flow culture
The bacteria are constantly kept in log phase. Nutrients are constantly fed in and culture medium are fed out. All factors have to be kept constant. Used in waste water treatment and production of single cell proteins.
Advantages of batch culture
Easier to control
Product may only be needed in small amounts
O Product may only be needed at certain
times
Bacteria grow better in batch culture
Disadvantage of batch culture
Low productivity
Disadvantages of continous dlow
increase the risk of contamination of materials
Advantage of continous flow
Higher volume production. Smaller storage space.
