7012 Bacterial Classification, Structure, and Replication

what sorts of tooth related issues can oral microbes cause?

gingivitis, periodontal diseae, endo infections, and orthodontic issues.

what is the pathway for oral microbes to cause systemic disease?

Infection by periodontal bacteria, oral gut microbiome axis, colonization of microbes in organs or tissues, prolonged inflammation causing disease.

what are the two forms of life (cell specific)

prokaryotes (bacteria and archaea) and eukaryotes (plasma mem enclosed nucleus + organelles)

what microbes live in extreme environments and don’t usually cause human disease?

archaea

what is the major difference between Scanning Electron Microscope and Transmission Electron Microscope?

SEM shows external detail, TEM shows internal cell features.

Are viruses cells?

NO- they can infect cells (bacteriophages)

how does a prokaryote differ from a eukaryote?

• 70S ribosomes (50S and 30S subunits)

• no nucleus (most have a haploid nucleoid)

• cell wall contains peptidoglycan (G+ or G- classification)

explain how the nucleoid region is structured.

single circular chromosome (haploid) that is non membrane enclosed

what group of molecules are missing from the phospholipid bilayer? With exceptions

no Sterols (type of steroid)

• except: mycoplasmas (no mem), some sphingolipids, and some fatty acids.

G+ bacteria cell wall vs G- bacteria cell wall:

G+ has a thick outer layer of peptidoglycan

G- has a layer of peptidoglycan sandwiched by another outer plasma membrane. this allows for a periplasmic space

what two units make up Peptidoglycan? how are they linked?

NAG (N-acetylglucosamine)

NAM (N-acetylmuramic adic)

link: B1-4 glycosidic bond btwn NAG and NAM

what does the enzyme transglycosylase do?

forms B1-4 linkage btwn NAG and NAM forming peptidoglycan

what enzyme links peptidoglycan NAG and NAM? what enzyme assembles peptidoglycan layers together by linking NAM and NAM?

transglycosylase, transpeptidase

what acids provide rigidity in the G+ cell wall?

teichoic (TA) and Lipoteichoic (LTA)

(LTA=LONGteichoic goes through peptidoglycan layer, TA are more surface)

what important space is in the G- cell wall? What does it do?

Periplasmic space: stores and produces antibiotic resistance enzymes.

the G- cell wall has an outer membrane that can support the attachment of _______?

lipopolysaccharide (LPS)

what kind of enzyme is produces in the periplasmic space G-?

B-lactamase

what does B-lactamase do

cut the B-lactam ring (in penicillin rendering it useless)

bacteria/microbes do not have mitochondria to make energy, where is it made?

ETC

which peptidoglycan subunit performs crosslinking?

NAM

what enzyme moved NAG and NAM and other proteins/enzymes to the cell wall to be added?

bactoprenol

what enzyme assembles peptidoglycan layers together by linking NAM and NAM?

transpeptidase

would a G+ or G- bacteria be more susceptible to an antibiotic?

G+ (G- has periplasmic space with antibiotic resistance and thin pep)

• G+ more susceptible to protoplast

why doesn’t G- have techoic acids? TA or LTA

No need for rigidity support , very thin peptidoglycan layer.

what are the components of a Lipopolysaccharide?

• O-antigen: antigenic (and variable)

• core polysaccharide (conservative among species)

• Lipid A: endotoxin (toxic to us, most outer layer of the LPS)

what is an antigen?

something that is foreign to our bodies (protein)

what does the G- cell wall have that G+ does not?

lipopolysaccharides and the periplasmic space

LPS layer endotoxins can cause extreme physical reactions like:

shock and fever

what innate human enzyme (antibacterial) do we have in our saliva and tears?

Lysozyme

how do lysozymes defend against bacteria?

hydrolyzes B1-4 bond btwn NAG and NAM

how does penicillin effect peptidoglycan?

inhibits transpeptidase blocking the NAM-NAM cross linkage (weakens the cell wall)

penicillin protoplast G+

entire removal of cell wall

penicillin spheroplast G-

partial cell wall removal

what color are G+ cells after staining?

methylene blue (peptidoglycan holds onto strong dye)

what color are G- cells after staining?

pink (insignificant peptidoglycan layer to hold onto blue dye)

what does pathogenicity describe?

the ability to cause disease

what attributes increase disease severity and ability to become infrctive?

virulence factors