Module 2: Bacteria (Part 1) Flashcards
What are the four main morphologies of bacteria?
1) Cocci
2) Bacilli
3) Vibrio
4) Spirilia
(pleiomorphic)
What is the determinant of bacterial morphology?
Cell wall organization
Cocci
Spherical
Bacilli
Rod-shaped
Vibrio
Curved-Rod (comma shape)
Spirila
Spiral Shaped
Why is morphology NOT enough for conclusive bacterial identification?
1) Many bacteria have the same morphology
2) Environmental stressors can alter morphology
Bacteria with variable morphology
Pleiomorphic
What are the main multicellular arrangements bacteria form?
1) Hyphae
2) Mycelia
3) Trichomes (mainly in cyanobacteria)
Hyphae
Irregularly branching filaments made of bacterial chains
Mycelia
3D network of hyphae
–> Hyphae go below or rise above the substrate (surface)
Trichomes
Smooth, unbranched chains of bacterial cells
(that may have a polysaccharide coating over the chain)
IN CYANOBACTERIA
What is the size range of most bacteria?
0.5um - 5um (LENGTH)
At what size is it too hard to see a structure with the naked eye?
<100um
What is needed to view bacteria?
Why?
A light microscope
Because most bacteria are less than 100um big
What is the size of the smallest eukaryal cell?
5um
Bacterial Size Exception:
What is the name and size of the biggest bacteria we know of?
Thiomargarito namibiensis
–> Typically ~100-300um (BUT can get up to 750um)
Bacterial size exception:
What is the name and size of the smallest bacteria we know of?
Mycoplasmas (a number of different kinds)
Usually ~0.2um in diameter
(Mycoplasma galicepticum = smallest known organism)
What is the morphology of mycoplasmas?
They have no cell wall so they are ultra-small, PLEIOMORPHIC bacteria
Cytoplasm
Aqueous environment enclosed within the plasma membrane
Nucleoid
The nuclear region; area of bacterial cells that contains the chromosomal DNA
Structure of bacterial DNA
Bacteria tend to have ONE big circular chromosome that gets bunched together into the nucleoid
What is the largest structure in the cytoplasm?
The nucleoid
Other than DNA what is also found in the nucleoid region?
1) Many proteins involved in DNA replication and transcription
2) Proteins involved in DNA condensing (Topoisomerase)
3) Cations (that also aid in DNA condensing)