BACTERIAL STRUCTURE AND CLASSIFICATION Flashcards
what is a coccus?
any spherical-shaped bacterium
what is a bacillus?
any rod shaped bacterium
what are the 3 groups of spiral bacteria?
vibrio, spirillum, and spirochete
what do spirilla bacteria look like?
a thick rigid spiral
what do vibrio bacteria look like?
they are curved or comma shaped
what do spirochete bacteria look like?
a thin flexibile spiral
what are the 3 domains of life?
eukaryotes, archaea and bacteria
how do we name bacteria?
in correct nomenclature…
family, genus, species and strain
what structural properties do all bacteria have?
cytoplasm, ribosomes, cell wall and chromosomes
what are plasmids?
small, circular, double-stranded DNA molecule that is distinct from a cell’s chromosomal DNA and replicate independantly.
how are plasmids moved between bacteria?
by horizontal gene transfer
whats the function of a flagella?
locomotion
what are pili?
hort, hair-like structures on the cell surface of prokaryotic cells.
they have a role in movement and adhering to surfaces
what are fimbriae?
long filamentous polymeric protein structures located at the surface of bacterial cells that allow the binding to specific receptor structures
what are 4 ways in which we can categorise bacteria?
if theyre gram positive, gram negative or acid fast
by morphology
by nutritional and enzymatic properties
by their DNA sequence
describe how you can determine where its a gram positive and gram negative bacteria?
if you stain with crystal violet and then wash with alcohol, gram positive bacteria stay purple whilst gram negatve bacteria look pink becayse they get washed out
what are the structural characteristics of gram negative bacteria?
they have an outer membrane and a cytoplasmic membrane
in between there is a thin periplasm (peptidoglycan layer)
what are the structural characteristics of gram positive bacteria?
they have a singular cytoplasmic membrane and a thick periplasm (peptidoglycan layer)
how are chlamydia and mycoplasma different to other bacteria?
they dont have conventional cell walls
how can we categorise bacteria based on morphology?
colony size
colour
size
appearance
what is a bacterial capsule?
a large polysaccharide layer that lies outside the cell envelope that can help the bacterium avoid desiccation by preventing water loss and protects the cell from phagocytosis
what are a bacteria with single cells and chains likely to be?
streptococcus
what are spores?
when some gram positive bacteria are under stress they can make them to ensure they are highly resistant to decissation, chemicals and temperature
what is serotyping?
to assign a microorganism to a specific serotype/strain
what makes up the bacterial genome?
the chromosomes and plasmids
what is horizontal gene transfer?
the non-sexual movement of genetic information between 2 bacteria (helped by bacteriophages)
what is vertical gene transfer?
when genes are transferred down generations
why do bacteria not take over our bodies if binary fission is so rapid?
because they run out of phosphate, carbon and nitrogen which they rely on
outline the number of bacteria x time graph during bacterial growth?
the lag phase is first when the bacteria are still adapting to their conditions
exponential logarithmic phase happens as they multiply
stationary phase occurs as nutrients begin to run out
death phase when no nutrients are available
