Microbiology Flashcards
(54 cards)
What is the name of the last universal common ancestor?
LUCA
List the 4 key principles of koch’s postulates
1- suspected pathogen must be present in all cases
2 - suspected pathogen must be grown in a pure culture
3 - cells from pure culture must cause disease in healthy animal
4- suspected pathogen must be reisolated and shown to be same as original
List the types of light microscopy
bright field
phase-contrast
dark-field
fluorescence
Which type of microscopy kills specimen?
bright-field
What type of microscopy uses polarised light?
differential interface contrast microscopy
Which type of microscopy measures forces between a probe and atoms on surface of specimen?
atomic force microscopy
Which type of microscopy couples a laser source to a fluorescent microscope
confocal scanning laser microscopy
What type of microscopy allows structures to be seen at the molecular level?
transmission electron microscopy
What type of microscopy shows the external surfaces of the cell?
scanning electron microscopy
What steps are required to construct a phylogenetic tree?
1 - isolate DNA
2 - make copies of rRNA gene by PCR
3 - sequence DNA
4 - analyze sequence
5 - generate phylogenetic tree
Where do protozoa live?
in soil, wet sand, fresh and salt waters
What are endospores?
- highly differentiated cells
- produced by certain bacteria
- resistant to heat, harsh chemicals and radiation
Describe the process of sporulation
1- essential nutrient is exhausted
2- vegetative cell stops growing
3- endospore develops within vegetative cell and is released
4- spore can remain dormant and germinates when conditions are good
How are endospores visualised
unreactive to most dyes - seen as unstained regions
What enables cells to stick to surfaces and each other?
fimbriae
List the functions of pili
- conjugation
- adhesion to specific host tissues and subsequent invasion
Describe the different attachment points of flagella
polar flagellation - attached at one or both ends
a tuft - group of flagella attached to one end
peritrichous flagellation - inserted at many locations
Where does the energy for rotation come from?
- proton movement across membrane through Mot complex
- exert electrostatic forces on helically arranged charges on rings
- attraction and repulsion drives rotation
What is meant by twitching motility
repeated extension and retraction of type IV pili
What is myxobacteria?
form fruiting bodies
Describe the life cycle of myxobacteria
1 - myxospores
2 - germination (gram-negative)
3 - vegetative growth cycle (gliding)
4 - aggregation
5- mounding
6 - differentiation
What are chemolithotrophs?
- feed on organic bacteria
- can oxidise H2, H2S and NH3
Describe the process of nitrogen fixation
N2 —> nitrogen fixation —> NH3 —–> nitrification —> NO-2 + NO-3 —–> denitrification —> N2
What catalyses nitrogen fixation?
nitrogenase
dinitrogenase –> contains iron and molybdenum
dinitrogenase reductase –> contains iron
