L14 Flashcards
three domains of life
Bacteria : prokaryotes
Archaea : prokaryotes
Eukarya : eukaryotes
Members of domain Bacteria are usually
- Single celled
- Cell walls with peptidoglycan
- Typical prokaryotic structure
- No membrane bound nucleus or organelles
Largest bacterium?
Thiomargarita namibiensis 100-300 μm, occasionally 750 μm – size of a full stop
Smallest bacterium?
- Mycoplasma 0.3 μm diameter, cultivated
- Ultrasmall uncultivated cells 0.009 μm (9 nm)
bacterium of average size
E.coli
New “largest bacterium” discovered in 2022
- Thiomargarita magnifica grows up to 1 cm long!
- found in Caribbean mangrove swamps
The two most common shapes of bacteria are:
1) coccus (plural cocci) (circular) -chains, clusters, pairs
2) and rod (also know as bacillus/ plural bacilli) -chains
Other bacterial shapes include:
- Filamentous
- Rigid spirals
- Comma shaped rods
- pleiomorphic
what are the 3 layers of a bacteria wall
- Capsule
- Cell wall
- Plasma membrane
Out - in
What structures do all bacteria have
- Cell wall (mostly)
- Plasma membrane
- Ribosomes
- Nucleoid
What structures do some bacteria have
- Capsules and slimes layers
- Fimbrae and pili
- Flagella
- Endospores
Cell wall
nearly all
Provides cell shape and protection
Plasma membrane
all
Selectively permeable barrier,
boundary of cell, nutrient and waste transport, respiration
Ribosomes
All
Protein synthesis
Nucleoid
all
Location of DNA, single chromosome
Capsules and slime layers
some
Resistance to phagocytosis, adherence to surfaces
Fimbriae and pili
(singular: fimbria, pilus)
some
Adherence to surfaces, DNA transfer, twitching and gliding motility
Flagella
(singular: flagellum)
some
Swimming and swarming motility
Endospore
some
Survival under harsh condition
Gram positive bacteria stain
Purple
thick peptidoglycan