Monera (Bacteria) Flashcards
micro organism definition
a small living thing
bacteria are…
unicellular
microscopic
prokaryotic
heterotroph and autotroph
prokaryotic definition
do not have a nucleus or cell enclosed organelles
shape of bacteria
round
rod
spiral
examples of bacteria
pneumonia
ecology
syphillus
tuberculosis
cholera
capsule function
further protection
plasmid function
resistance to drugs/antibiotics and used in genetic engineering
flagella function
movement
motile
are bacteria motile?
yes — flagella
How do bacteria reproduce?
Asexually, by Binary Fission
Binary Fission steps
- cell reaches a certain size & DNA strand replicates itself
- Now 2 identical strands of DNA
- Cell ELONGATES with a strand of DNA attached to each side
- Cell splits into 2 similar sized cells
Mutations in Bacteria
Offspring genetically identical.
Short life span of bacteria mean that any new variation produced by a mutation can be passed quickly to a large number of bacteria.
This is how bacteria evolve and become resistant to new antibiotics.
Nutrition in Bacteria
Heterotrophic : Saprophytic
Eg: Bacteria of decay
Nutrition in Bacteria
Heterotrophic : Parasitic
Eg: Bacillus anthracis
Nutrition in Bacteria
Autotrophic : Photosynthetic
Eg: purple sulphur bacteria
Nutrition in Bacteria
Autotrophic : Chemosynthetic
Eg: Nitrifying bacteria
Photosynthetic bacteria definition
Use light energy to make food
eg: purple sulphur bacteria
Chemosynthetic bacteria definition
Use energy from chemical reactions to make food
eg: nitrifying bacteria
Saprophytic bacteria definition
live off dead plants / animals (carbon cycle)
eg: bacteria of decay
Parasitic bacteria definition
take food from live host, some cause disease
eg: bacillus anthracis (causes anthrax)
Factors affecting growth of bacteria
(limiting factors)
Temp
pH
Oxygen Conc
External solute Conc
Pressure
- Temperature
most bacteria grow well between 20/30°C
some can tolerate higher temps without enzymes being denatured
low temps slow down rate of reaction of enzymes resulting in SLOWER GROWTH
- pH
If bacteria is placed in an unsuitable pH it’s enzymes will become denatured.
Most bacteria grow at pH7
Some can tolerate very low/high pH values.
- Oxygen Concentration
Aerobic bacteria need oxygen for respiration (eg: streptococcus) (this is why oxygen is sometimes bubbled through bioreactors)
Anaerobic bacteria don’t require oxygen to respire.
- Faculative anaerobes can respire with or without (eg: ecoli)
- Obligate anaerobes can only respire in the absence of oxygen (eg: clostridium tetani)
Aerobic bacteria
need oxygen to respire
Anaerobic Bacteria
don’t need oxygen to respire
Faculative anaerobes
can respire with or without oxygen
Obligate anaerobes
can only respire without
- External solute concentration
Bacteria can gain or lose water by osmosis
If external solute conc is
Higher than the bacterial cytoplasm - water will move out of bacteria, causing dehydration (tinned fish, fruits)
Lower than the bacterial cytoplasm, water will enter bacteria (cell wall prevents bursting)
- Pressure
growth of bacteria is inhibited by high pressures
some can withstand high pressures
Pressure tolerant bacteria for use in bioreactors can be formed by genetic engineering techniques (GMO)
Economic importance of bacteria
Beneficial
lactobacillus bulgaricus converts milk to yogurt and cheese
antibiotics can be formed
bacteria are active in carbon and nitrogen cycles
Economic importance of bacteria
Harmful
pathogenic bacteria can cause disease in humans and animals (pathogens)
bacteria can cause food spoilage
bacteria can cause tooth decay
pathogen definition
organisms that cause disease
Lag phase
Bacterial cells adapting to new conditions.
They’re producing enzymes to digest the nutrients
Rate of growth begins to increase at end of lag
Log phase
Rapid period of growth due to:
bacteria developing enzymes and there are plenty of nutrients
lack of waste products being produced
Stationary phase
Rate of growth levels off
Death rate equals birth rate
lack of food, space, moisture and oxygen
Death phase
Durina this phase more bacteria are dying than are being produced.
This is because :
- few nutrients are left
- bacteria are poisoned by the waste produced in such large numbers
- This the rate of grouth is falling
favourable conditions for bacteria growth
O2
Food
Space
Moisture
PH
Temp
Endospore formation
Occurs during binary fission
1. DNA replicates itself
2. One of the new strands of Dna becomes enclosed in a tough walled capsule called an endospore, formed inside the parent cell.
3. Parent cell breaks down
4. Endospores can remain dormant for long time
5. When conditions are favourable new bacteria can be formed again and continue to reproduce
Bioreactors definition
a large, stainless steal vessel which biological reactions take place in the presence of micro organisms.
Batch food processing
- A fixed amount of nutrient is added to bioreactor at start
- Micro organisms go through lag and log and stationary phase where most product is formed
- Product is formed over short period of time.
- Process starts again
Continuous flow processing
- Nutrients added all the time
- Micro organisms mainly go through log phase where most product is formed
- Long period of time
Antibiotics
antibiotics are chemicals produced by micro organisms that stop growth or kill other micro organisms without damaging human tissue (NOT VIRUSES)
Antibiotic resistance
Occurs during binary fission
2. mutations in bacteria genes cause antibicic resistance
3. This is known as natural
selection
4. These changes in the genes can be passed on quickly to new bacteria » surviving chains multiply
5. This leads to build up of an antibiotic resistant population.
how does antibiotic resistance occur
misuse of antibiotics
