Prokaryotes Flashcards
gram staining
used to detect peptidoglycan in cell walls
- shape is not enough to distinguish different species of bacteria
gram +
exposed peptidoglycan
- turn purple
gram -
has membrane that covers peptidoglycan
gram staining steps
- apply crystal violet
- apply iodine
- apply alcohol wash
- apply counterstain
what is the purpose of applying crystal violet?
it stains all bacteria purple
what is the purpose of applying iodine?
it fuses the crystal violet to the peptidoglycan which stains the gram + cells
what is the purpose of applying alcohol wash?
removes excess dye
what is the purpose of applying a counterstain?
it stains the bacteria green or pink
types of resistance in prokaryotes
- capsule
- endospore
capsule
membrane that protects cell wall
- on gram - which makes them harder to stain
endospore
copy of DNA stored in a resistant capsule that can remain dormant
- when environment is right, it will spawn again and be resistant
4 ways bacteria maintains genetic variation
- mutations
- conjugation
- transduction
- transformation
how does bacteria replicate?
binary fission
mutation
random change in nucleotides
conjugation
bacteria can transfer plasmids (DNA) to other bacteria
- swap DNA through a sex pilus
transduction
bacteria get near DNA from viruses
- DNA gets cut up from original cell and combines with new cell DNA to make new variation
transformation
bacteria takes up DNA from the environment
- when bacteria die their DNA sits in the environment and can be picked up again
