UNIT 3: Kingdom Monera Flashcards
Bacteria
Ubiquitous
Most numerous living organism on earth.
Prokaryotes - no membrane bound organelles
Structure of bacteria
Have a cell wall and cell membrane, but no organelles.
Many bacteria have an additional layer of protection called the capsule and flagella (for movement)
Capsule
Slime layer for protection
Cell wall
Structure and protection
Cell membrane
Selectively permeable controlling what enters and leaves the cell
Flagellum
Movement
Chromosome
DNA and protein carrying genes
Ribosome
Protein synthesis
Cytoplasm
Liquid portion of the cell in which all metabolic reactions occur
Plasmid
Circular piece of DNA that gives the bacterium special traits such as antibiotic resistance
Spherical bacteria
Round and spherical in shape e.g. staphylococcus aureus (bacterium normally present on human skin)
Spiral bacteria
Spiral or helical shape e.g. helicobacter pylori (bacterium that often causes stomach ulcers)
Rod bacteria
Elongated rod shape e.g. lactobacillus casei (bacterium found in milk)
Bacterial reproduction
Bacteria reproduce by binary fission
Binary fission
Asexual reproduction in bacteria
Endospore
Thick, tough-walled, dormant and dehydrated bacterial cell formed during unsuitable conditions
Process of endospore formation
- conditions become unfavourable for the bacterial cell.
- cell undergoes asymmetrical binary fission with the smaller cell being engulfed by the larger cell.
- thick wall, called the cortex, forms around the engulfed cell.
- outer coat forms around the cortex
Nutrition in bacteria
Nutrition - way in which organisms obtain and use food
- Autotrophic
- Heterotrophic
Autotrophic nutrition
Way in which organisms make their own food.
Autotrophic nutrition (chemosynthetic nutrition)
Way in which bacteria make their own food from inorganic chemicals e.g. nitrifying bacteria produce nitrates (used in protein synthesis) from ammonia.
Autotrophic nutrition (photosynthetic nutrition)
Way in which bacteria use sunlight to make their own food e.g. purple sulphur bacteria produce carbohydrates from carbon dioxide using light energy
Heterotrophic nutrition
Way in which organisms obtain their food from other organisms
Heterotrophic nutrition (saprophytic nutrition)
Way in which bacteria feed off dead organic matter e.g. bacteria of decay
Heterotrophic nutrition (parasitic nutrition)
Way in which bacteria feed directly off living organisms e.g. E.Coli
Factors effecting bacterial growth
Temperature Oxygen concentration Ph External solute concentrations Pressure
Temperature
Lower temperatures mean lower enzyme activity and a much slower rate of bacterial binary fission
Oxygen concentration
Most bacteria need oxygen to survive (aerobic bacteria).
- There are bacteria that are killed by oxygen called obligate anaerobic bacteria.
- There are bacteria that cannot use oxygen but tolerate its presence called aero tolerant anaerobic bacteria.
- There are bacteria that can use oxygen but do not depend on it called facultative anaerobic bacteria.
pH
Changes in pH effect enzyme function meaning pH values outside of optimum mean that certain bacteria cannot survive.
Most bacteria require a neutral pH.
There are bacteria that can survive in very acidic conditions called acidophiles.
There are bacteria that can survive in very alkaline conditions called alkaliphiles.
External solute concentrations
The concentrations of the solution surrounding the cell effects the rate of osmosis.
If osmosis occurs too quickly in either direction (in or out of the cell) then the cell may die
Pressure
Fluid pressure effects all living organisms.
High pressures are used by many companies in the food industry to sterilise (kill micro organisms) the food.
High pressure kills microorganisms by breaking the cell wall and cell membranes
Growth curve of microorganisms
- Lab phase
- Log phase
- Stationary phase
- Decline phase
- Survival phase
Lag phase
Microorganisms are adjusting to a newly colonised environment
Log phase
Microorganisms start to reproduce exponentially
Stationary phase
Nutrients begin to run out / toxins begin to build up causing reproduction to slow down and death to increase
Decline phase
Death of microorganisms is at a higher rate than reproduction due to build up in toxins
Survival phase
Some microorganisms produce endospores and can survive the harsh conditions
Beneficial bacteria
Lactic acid bacteria
E. Coli
Lactic acid bacteria
Bacteria found in dairy products that help in the production of many diary products. They also colonise our digestive systems producing lactic acid and inhibiting the growth of harmful bacteria
E Coli
Bacteria of the large intestine are responsible for producing vitamins
Harmful bacteria
Strep throat bacteria
Tuberculosis bacteria
Strep throat bacteria
Cause of sore throat and scarlet fever
Tuberculosis bacteria
Cause of tuberculosis
Antibiotics
Chemicals produced by microorganisms that inhibit the growth of, or kill, other microorganisms without damaging human tissue
Overuse of antibiotics
Has led to the emergence of emergence of antibiotic resistance among bacteria strains such as MRSA.
Resistance to antibiotics occurs when one bacterium in a population develops a mutation that enables it to avoid the effects of the antibiotics.
This one bacterium then divides to form a new colony of resistant bacteria that are unaffected by the antibiotic
Food processing
Taking raw ingredients and converting them to food fit for consumption
