Microbial Diversity Flashcards
What are the three shapes of bacteria?
- Spheres
- Rods
- Spirals
What is the difference between gram positive and negative bacteria?
Gram-positive: has a thick peptidoglycan layer, external to the cell membrane
Gram-negative: has a thin peptidoglycan layer and is overlaid by an outer membrane
What are the steps to gram staining?
- Fixation
- Crystal violet
- Iodine treatment
- Decolorisation
- Counter stain safranin
How do capsules act as virulence factors?
- Allows bacteria to hide from the immune response
- Aids sticking to tissues
- Extra layer improves survival in conditions
What are flagella and what are they composed of?
- Long helical filaments extending from the cell surface, aid bacteria in moving around
- Are made form protein components (flagellants) which are strongly antigenic
What are Endospores?
- Tough, dormant, non-reproductive bacteria
How do pills act as virulence factors and what do they help with?
- Their antigens can be changed, allowing the bacteria to avoid immune recognition
- May help to prevent phagocytosis, reducing host resistance to bacterial infection
What are Frimicutes?
They are bacteria that have G and C bases making up less than 50% of all their bases
What are Actinomycetes?
They resemble the fungi in that they produce spores and form filaments
What are bacteroids?
- They are bacteria widely distributed in the environment, including I soil, sediments and sea water as well as in the guts and on the skin of animals
What are bacteria?
Single-celled prokaryotes, their DNA forming a long circular molecule but not contained within. defined nucleus
What do toxins, secreted by bacteria do?
Alter or destroy host cells or hyper stimulate the host immune response
Distinguish between the two types of toxins
Exotoxins: Separate factor released from the pathogen into host tissue
Endotoxins: part of the bacterial cell wall directly activates the immune system when the microbe dies, these can induce clotting, bleeding, inflammation, fever
