- photosynthetic bacteria
- account for up to 30% photosynthetic productivity
- responsible for oxygenating atmosphere
- one of the most abundant bacteria
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Describe the structure if cyanobacteria
- cytoplasm has an extensive thylakoid membrane where photosynthesis occurs
- usually forms communities + extensive structures- sheets, filaments, hollow balls
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Describe the bacillus species
- gram +ve bacteria
-aerobic spore former
- isolated from soil, water + GI tract of animals
- some are extremophiles- adapted to extreme conditions by evolving enzymes that function under these condition, change in cell envelope + DNA
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How are spores formed?
- asymmetrical cell division with endospore forming at one end
- septum forms to seal off the endospore
- lysis of mother cell releases endospore
- roughly 8 hours
Dipicolinic acid
Purpose= dehydrate core contents + bind with DNA to stabilise it against heat
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What is the main function of a spore?
aid dispersal- spread easily + can live in the environment for long periods of time
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Name the 3 main bacillus species
1. B. anthracis
2. B. cereus
3. B. thuringiensis
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Describe B. anthracis
- causative agent of anthrax- affects animals + humans
- contracted through inhalation of spores (pulmonary a.), consumption of contaminated meat (GI a.), penetration of skin via break/ insect bite (cutaneous a.)
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What is the most serious type of anthrax?
Pulmonary- difficult to treat once clinical signs are evident
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How does anthrax cause disease?
- capsule can prevent phagocytosis of bacteria + is encoded on plasmid
- produces toxin encoded on different plasmid- 3 components: edema factor, protective antigen (PA), lethal factor
- protective antigen is required for other toxins to be taken up by ho
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Describe B. cereus
- causes gastroenteritis
- food-borne- contamination of food from environment, not animal sources
- causes 2 types of disease: 1. emetic (vomiting 30 mins- 6 hrs after consuming food containing emetic toxin) 2. diarrhoeal- consumption of spores in food th
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What does B. thuringiensis cause?
attacks insect larvae by protein crystals associated with outside of spores + undergo proteolytic cleavage in insect larval gut
- toxin finds to intestinal epithelial cell to make it leak stomach acid + enzymes into body
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Name the 3 types of parasitic gram -ve bacteria and describe what they do
1. Vampirococcus- attaches to outside of bacteria + absorb contents
2. Bdellovibrio- penetrates outer membrane of prey bacteria to obtain nutrients
3. Daptobacter- collides with prey bacterial cells + penetrates through cytoplasm to use for energy + nutr
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What is a bacteriophage?
a virus that infects bacteria
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What is the definition of commensal?
a symbiotic relationship b/w two organisms in which one/ both can benefit
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What is an example of commensal with E coli?
E coli in GI tract gains nutrients + produces Vitamin K which is used by host
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What does normal bacterial flora do?
prevent overgrowth of certain bacteria, including pathogens
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How do bacterial cells communicate with each other?
They produce small molecular weight compounds which can detect the number of cells present = quorum sensing
- allows bacteria to ensure there is a significant number of cells available before expressing certain genes/ exhibiting certain behaviours
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How do nitrogen- fixing bacteria communicate with plants?
signal to fine hairs on plant roots to stimulate growth of root nodules where bacteria fix nitrogen for the plant in exchange for nutrients
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What are bacterial biofilms?
structured microbial communities that form on surfaces + are protected by a polysaccharide matrix
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How are biofilms formed?
formed when a cell adheres to a surface + micro-colonies are formed once a certain density is reached- polysaccharide produced + coated over cells for protection
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What is the purpose of biofilm
helps trap nutrients, keep bacteria attached to surfaces in flowing surfaces (e.g. rivers, teeth)
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Other cards in this set
Card 2
Front
What are cyanobacteria?
Back
- photosynthetic bacteria
- account for up to 30% photosynthetic productivity
- responsible for oxygenating atmosphere
- one of the most abundant bacteria
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