BIO 315 Lecture Notes - Lecture 2: Vibrio, Myxobacteria, Conformational Change
Lecture #2 Bacteria 06/01/17
- Bacteria is about ~0.5 micrometers (bigger than virus, smaller than eukaryotic cell)- viral
particles can go inside bacterial cells
- Mycoplasma- very small (several million can fit on tip of human hair); thiomargarita (gram
neg Proteobacterium)- very large
- Cocci sphere, bacilli rod (E.coli small bacilli; anthracis large bacilli), vibrio C-shape, spirilla
spiral; varied shape bacteria do not have cell wall (pleiomorphic- keep changing)
- Bacteria are single-cell; cyanobacteria (photosynthesis) and myxobacteria (looks like
plant/tree- feed on insoluable inorganic substances- larger genome 9-10 million
nucleotides) arranged in a way that looks like chain of cell (multicellular), but actually
function as individual cells
- Plasma mem, inside is cytoplasm ribosome and large nucleoid with no defined nuclear mem
(genetic material present- analogous to nucleus- ours is super coiled because small volume),
outside is cell wall capsule and external limbs (flagella fimbrae pilli)- between PM and CW is
periplasmic space (critical for CW formation and houses organelles)
- *Table “Features of the bacterial cytoplasm”; ribosomes (translation machinery common in
every cell, but not same components); plasmids present in some bacteria (not essential to
metabolism- have DNA independent to main source-carry certain genes- provide resistant
to drugs); inclusion bodies (store C, P and other essential elements required for growth); gas
vesicles; magnetosomes; cytoskeleton (homologs of actin and tubulin)
- Cytoplasm- H2O, protein, organic molecules, protein filaments responsible for shape of
bacterial cell, single circular chromosome (IN GENERAL; exceptions exist),
- Inclusion/alementary bodies- granules C, globules S, gas vesicles buoyancy, magnetosomes
orient bacteria to direction of food- environ low in oxygen (10% less than atmospheric O, 8-
10% CO2- microaerophilic environ, like O but not atmospheric; compilobacter and
helicobacter (H.pylori) have magnetosomes and infections last long time symptoms severe
pain in abdominal cavity; aeorbic bacteria NEED oxygen; anaerobic bacteria O is toxic;
facultative anarobes- indifferent to O- E.coli), carboxysomes fix C in photosynthesis
- Cytoskeleton- organize stuff inside cell- MreB forms actin-like helical bands next to PM,
after polymerization form ring-like structure; FtsZ aids like tubulin where cell division,
assembled in ring at future cite of septum where the cell starts dividing (homologs)
→ Distribution of plasmid not uniform (plasmids do exist in eukaryotic cells and
archaea)- segregation is random (4 plasmids can divide into 3 and 1)- carried out by
ParM (bound to ATP, actin like protein), ParR (binds to DNA, attached to plasmids,
present on DNA as adaptor protein) and ParC (DNA site)- system ParMRC; ParR and ParC
usually together- once all together, start stretching to oppo sides
- Plasma mem- phospholipid bilayer (fats, glycerol has 3C where 2Cs attached to fatty acids
and 1C attached to phosphate, fatty acids hydrophobic and inside)- keep cytoplasm inside,
separates external environ from internal- peripheral and integral (touch both sides of PM)
proteins
→ Cholestrol- stabilizes PM; hopanoids are functional analogs in bacterial PM- influence
permeability and rigidity (Archaea does not have)
→ Osmosis- flow of solvent/liquid from higher concen to lower across a semi-
permeable PM- CW helps bacterial cells survive osmotic pressure situations
Document Summary
Bacteria is about ~0. 5 micrometers (bigger than virus, smaller than eukaryotic cell)- viral particles can go inside bacterial cells. Mycoplasma- very small (several million can fit on tip of human hair); thiomargarita (gram neg proteobacterium)- very large. Cocci sphere, bacilli rod (e. coli small bacilli; anthracis large bacilli), vibrio c-shape, spirilla spiral; varied shape bacteria do not have cell wall (pleiomorphic- keep changing) Bacteria are single-cell; cyanobacteria (photosynthesis) and myxobacteria (looks like plant/tree- feed on insoluable inorganic substances- larger genome 9-10 million nucleotides) arranged in a way that looks like chain of cell (multicellular), but actually function as individual cells. Cytoplasm- h2o, protein, organic molecules, protein filaments responsible for shape of bacterial cell, single circular chromosome (in general; exceptions exist), Inclusion/alementary bodies- granules c, globules s, gas vesicles buoyancy, magnetosomes orient bacteria to direction of food- environ low in oxygen (10% less than atmospheric o, 8-
