Bacteria Flashcards
General characteristics of bacteria
- No organelles present
- All actions take place in the cytosol or cytoplasmic membrane.
- Cell wall is made up of peptidoglycan.
- No chlorophyll
Which other organism is a prokaryote like bacteria?
Blue-green algae
Where does protein synthesis take place in bacteria?
In the cytosol with structurally different ribosomes.
Where do we see true branching in bacteria?
Higher forms like Actinomycetes
What is the maximum absorption of bacteriochlorophyll?
Infrared
What are the varieties of bacteria based on body shape?
Cocci (oval) Bacilli (Rodlike) Vibrios (Comma-like) Spiralli Spirochaetes (flexible spiral), Actinomycetes (branching, filamentous with mycelia),
Cocci based on cell arrangement
Micrococci (Singly)
Diplococci (Doubly or in pairs)
Streptococci (Chains)
Tetracocci (Two planes to form groups of 4)
Sarcinae (cuboidal arrangements of eight cocci)
Staphylococci ( irregular (grape-like) clusters)
What is the main function of the cell wall in bacteria?
To prevent the cell from expanding and eventually bursting due to water intake. It also gives shape to the cell.
How can the cell wall of a bacteria cell be destroyed?
By the action of lysosomes. It is easily lysed, metabolically active but unable to reproduce.
What is the external structure in bacteria?
Murein
What are the components of bacteria cell?
A rigid cell wall
A plasma membrane
What is the bacteria without the cell wall?
Protoplast
How can a bacteria cell be damaged?
By the action of antibiotics and lack of chemicals
Typically examples of bacteria based on morphology
Typical examples include:
coccus (circle or spherical) bacillus (rod-like) coccobacillus (between a sphere and a rod) spiral (corkscrew-like) filamentous (elongated)
What is another name for peptidoglycan?
Murein
Where is peptidoglycan located?
It is located immediately outside of the cytoplasmic membrane.
What is the function of the cytoplasmic membrane?
Present in both Gram +ve and -ve, it is the tiny layer lining the inner surface of the cell wall ad acts as a semi-permeable membrane controlling the flow of metabolites in and out of the cell.
Describe ribosomes in bacteria
It is the centre of protein synthesis and is slightly smaller than those in prokaryotic cells.
What is the outermost layer of the bacteria?
Capsule, made up of polysaccharides
Describe the nucleus in bacteria
It is not distinct and with no nuclear membrane.
What are the cytoplasmic inclusions in bacteria?
They are aggregates of polymers produced when there is an excess of nutrients in the environment and are a storehouse for granules.
Describe the flagellum
It is like a helical filament extending from the cytoplasmic membrane to the exterior part of the cell
What is the classification of bacteria based on the presence of flagella?
Monotrichous (1 flagellum)
Amphitrichous (Either a single or tufts at one end)
Lophtrichous (Tufts of flagella at one end)
Petrichous (All over the surface)
How do bacteria reproduce?
By binary fission
Why do many cells in a growing bacteria population have two nuclear bodies?
Because in bacteria, nuclear division precedes cell division.
What makes bacteria spores interesting?
- Its protoplast is concentrated at one end of the cell
- They are not reproductive spores or storage granules
- They are highly resistanct
What are the stages of bacteria growth?
- Increase in individual cells
- Increase in the number of cells
What happens to a bacteria cell when environmental conditions are not favourable for vegetative growth?
It forms highly resistant spores
What are the layers of a bacteria spore?
Core
Cortex
Spore Coat
What is the economic importance of bacteria?
- They produce antibiotics
- Breakdown of waste into CO2 and water in sewage treatment plants
- Bioremediation (treatment of environmental pollution)
- Food production
- Medicine
- Bioreactors
- Diseases
- Toxic
