Microbio w2 (bacterial classif, morph, phys)

taxonomy?

systematic classif and categ of orgs into ordered groups

based on struct, genetics, hierarchy

whats binomial nomenclature

• 2 part naming sys

• Genus (capital) species (lower)

• ex: Streptococcus mutans

why do we classify them?

• Identify microorganisms

• Understand relationships

• Organize biological diversity

• Predict behaviour & disease potential

3 domains of life (BAE)

1. Bacteria - most pathogens

2. Archaea - extreme environ

3. Eukarya - humans, plants, fungi

Archaea (all need to know)

• prokaryotic (no nuc mem bound orgs)

• extreme environ

• no peptidogylcan (polymer forming cell wall of bact)

review

bacteria morphology (shape & arrange)

Shapes

• bacilli - rod

• cocci - circle

• spirilla - spiral

• vibrio - curved or comma

strept = chain

staph - cluster

diplo = pair

cellular microorgs (2 grps are?) know to this extent

1. Prokaryotes - (bact) no mem bound orgs/nuc, no nuc mem

• one circular chrom made of dna

1. Eukaryotes- nuc mem (cytoplasm & nuc)

most prev oral bacteria name? details

• Streptococcus mutans (on enamel)

• break down dietary sugars > lactic acid = destroy enamel > caries

intracellular bact structures - cell wall

• makes cell rigid

• inner layer of peptidoglycan (polymer in prokar)

• outer mem varying in comp

peptidoglycan = derived in peps & sugars that make up the molec

• rigidity

cytoplasmic mem = lies just inside peptido layer & has phospholipid bilayer

TLDR = cell wall (peptido covered in outer mem) > cytoplas mem w phospholipid bilayer

FXNS ****

• active & selective transport

• electron transp & oxidative phosphorylation

• secretion of enzymes & toxins

• support receptors and other proteins

cytoplasm

• gelatinous semi-transparent matrix filling most of cell

• mainly water & dissolved inorg ions n stuff

in prokar cells = includes nucleoid region (where dna is; not mem bound)

in eukar cells = excludes nuc; it’s enclosed by double mem (nuc envelope

ribosomes

• photosynthesis site

nuclear material/nucleoid (in prokar)

• non-mem-bound region containing cell’s DNA

• DNA is single circular coiled chrom

external cell wall structs

1. flagella - propel & guide toward nutritional + avoid preds

2. fimbriae & pili - hair like, mainly on gram-neg, adhesion of bact to receptors on human cell surf (initiation of infect

• seex pilus form attach betw male/fem during conjugation (gene transf betw bact

3. capsule - amorphous (lack shape) gelatious layer surround bacteria (NOT ALL HAVE)

• polysaccharide & protein

• mediate adhesion of bact > tissue

• can hinder/inhibit phagocytosis (inhib blood cell from eating it)

what capsule have to do with virulence factor

• outermost layer

• stop WBCs like macropage from swallowing

• evade immune sys by hiding inner bacterial parts

• help w attachment

periplasmic space (gist)

• only in gram neg

• betw inner plasma mem & outer

• move & store nutrients round

antimicrobial mode of action

will give list of antibiotics - which inhib protein synth

tldr specif antibiotics targ specific bact/micros

b-lactams (penicillin ampicillin cephalosporin) - interfere w cross-linking of cell wall petidomolecs

• targ cell wall

• also bacitracin inhibs peptido formation

erythromycin and teracycline - target ribosome > inhib protein synth

polyenes like nystatin & amphotericin - affect cytoplasmic mem by disrupting yeast cell mem

metronidazole - affect nucleic acid rep by interfere w dna rep

idoxuridine & aciclovir - affect nucleic acid rep by interfere w dna synth in dna viruses

antibiotics work because they…

target bacterial structs

primary target of penicillin

cell wall synth

plant vs animal cell wall

• plant cell wall have cellulose

• animal no cell wall, just cell membrane

what allows us to use gram stains

structural differences in bacteria

whats gram stain

4-step staining process for sep bacteria in 2 grps

1. crystal violet dye

2. iodine sol

3. alcohol wash (removes crystal violet from gram neg)

4. safranin

results

gram-pos > purple

• usually aerobic (need O2)

• its thicker walls are dehydrated by application of decolorizer, pores get smaller

gram-neg > pink

• typically anaerobic (no O2)

• walls too thin to retain crystal violet-iodine complex

gist?

neg bacteria have outer mem, pos dont

neg bacteria have LPS (cause inflam), pos dont

neg retains red/pink (safranin), pos retain crystal violet

gram neg more resistant bc it has outer mem

presence of LPS in neg contrib to ability to trigger strong inflamm response

spore?

• reproductive mech (usually haploid+unicell)

• can dev > new org by mitosis (w/o fuse) & prod multicell gametophyte

bacterial spores are Endospores

• dormant survival structs

• very resistant to heat, chems, drying

• found in gram-pos bact

• dental bact like streptococcus usually pos > most can form endospores (not strept)

these are highly heat and disinfectant resistant

relevance - infection transmit, instrument sterility, patient safety

endospores resists sterilize