Microbiology - Test 1

eukaryotes: many types of organelles, sterols in the PM, 80S ribosomes (60S + 40S), absence of cell wall or cellulose, long-lived mRNA, intervening introns
Prokaryotes: no true organelles, no sterols, 70S ribosomes (50S + 30S), peptidoglycan cell wall, short-lived mRNA, colinear

Continuous sequence of nucleotides in the DNA codes for a continuous sequence of amino acids in the protein. With colinearity, the number of nucleotides in the gene is proportional to the number of amino acids in the protein.

T

1. G +
2. G +
3. G -
4. G -

1. -----
2. bacteria stains red
3. stain washes out of non-acid-fast cells
4. non-acid-fast cells counter-stain blue

members of Mycobacterium

Mycobacterium tuberculosis

leprosy

rods (short, long, curved), cocci, fusiform, spirochete, square

1. Streptococcus species
2. Treponema species
3. Veillonella species
4. AA (aggregatibacter actinomycetemcomitans
5. Bacteriodes or Porphyromonas gingivalis species

1. metabolic characteristics (fermentation rx); MacConkey agar
2. immunospecific rx (Ag/Ab); ELISA

1. 16S rRNA gene sequencing (species identification)
2. PCR (identify any gene)
3. genomic sequencing

G+, cocci, facultative, catalase +

G+, cocci, facultative, catalase -

G-, cocci

G-, rods, anaerobes, nonmotile

G-, rods, facultative, asaccharolytic (incapable of metabolizing glucose, CHO)

PG (thick), pilus/fimbriae, flagellum, cytoplasmic membrane, capsule/glycocalyx

cytoplasmic membrane, PG (thin), periplasmic space, outer membrane (OM), flagellum, pilus/fimbriae, capsule/glycocalyx

enclosing membrane, intracytoplasmic membrane, plasma membrane, cell wall

lack peptidoglycan cell wall, uses exogenous sterols in their membrane.

yes, all bacteria cytoplasmic membrane contain the common phospholipids.

glycan backbone (repeating unit of NAG and NAM), tetrapeptide side chain, amino acid cross bridge

beta (1->4) linkage

NAM

L-alanine, D-glutamic acid, meso DAP*, D-alanine
*meso DAP = D,L-diaminopimelic acid

D-alanine

It attaches D alanine (4) in one side chain to meso DAP (3) in another side chain of another glycan backbone.

hypertonic
hypotonic

it cleaves btw NAM and NAG, and produce cross-linked disaccarides

LTA: G+
LPS: G-

1) glycolipids
2) polyglycerophosphate
or
1) glycolipid
2) ribitol and phosphate

lipid A (toxic), core, O-Ag (serotype)

2x NAG, FA, phosphate group, 8-carbon sugar (KDO)

cytoplasmic membrane
outer leaflet of outer membrane

LPS anchors on the outer leaflet of outer membrane, lipid A is also at the outer leaflet of outer membrane. The inner leaflet is composed of the same phospholipid as the cytoplasmic membrane. This gives a asymmetry to the outer membrane.

Outer membrane have porin, provide aqueous channel. Anything larger than pentasaccharide is excluded from entrance thru porin.

mycolic acid, arabinogalactan

LAM, mannophosphoinositide, phosphoinositol

K-Ag

polar, peritrichous (more than 1), axial filament (found on spirochete)

common, sex

adherence, coaggregation (involve >2 species), conjugation

H-Ag

C, H, N, O2, S

T

superoxide dismutase

step 1: catalyzed by superoxide dismutase to produce hydrogen peroxide.

step 2: hydrogen peroxide is catalyzed by catalase or peroxidases to produce water.

thermophiles: 50 - 60 oC
mesophiles: 20 - 40 oC
psychrophiels: 10 - 20 oC

host commensals and pathogens

type: active
substrate: glucose, fructose, sucrose

Enzyme I, HPr: soluble cytoplasmic components, transport of phosphate group from PEP to donate to sugars
Enzyme II and III: membrane bound components used for transport of specific sugars.

Yes

2 ATP, 2 NADH

pentose-5-phosphate

1 ATP, 1 NADH, 2 NADPH

linear array of genes: DNA has info on it.
characteristic copy number: there's finite numbers of plasmids in a bacteria. there's a gene that dictates the copy number.

drug resistance factors
bacteriocinogenic factor: bacteriocin (proteins that kill other bacteria). colicin if produced by E coli.
fertility (F) factor: codes for proteins that facilitate conjugation (F pilus)
toxinogenic factor: codes for bacterial toxins that kill plant or animal cells, surface Ag (capsules or pili)
metabolic factor
cloning vector: commercially available
cryptic plasmid: unidentified functions

linear molecule
move by non-homologous recombination

inverted repeat, genes for transposition, core region (structural genes)

direct repeat

competence factor, autolysin, niclease, DNA-binding proteins, competence specific protein

dsDNA

Because PG and DNA are both negatively, so competence-specific protein prevent repelling.

During transformation, sometimes F plasmid become incorporated into the chromosome in low frequency. This creates Hfr (high frequency recombinance) cells. The cell become super DNA donor. It can mate with an F- cells at higher frequency than the original donor.

F' strain is when F plasmid incorporate a small portion of the host cells. This F' plasmid can be transformed into another F- cells, and bacterial genome is transferred.

the integrated F plasmid

virulent and temperate

lysogenic cycle
temperate phages may be induced to become virulent, and go through lytic cycle.

extracellular phage

effector, enzyme and substrate. binding of effector changes conformation of the enzyme

cumulative feedback inhibition
sequential feedback inhibition
feed-forward inhibition or activation

pyruvate kinase
lactate dehydrogenage
pyruvate formate lyase

heterolactic fermentation
homolactic fermentation

negative control: repressor not bound to the DNA = transcription

positive control: repressor bound to the DNA = transcription

lag phase, log (exponential) phase, stationary phase, death phase

catabolite repression

Fungi: beta-lactam
G+: aminoglycoside
G-: quinoline

serial dilution of antibiotics in test tubes that have bacteria. MIC is when the liquid is clear, indicating no bacterial growth.

bacteria is plated on the agar plate and disk of different concentration of antibiotics is placed on the plate. zone of inhibition is observed.

D-cycloserine and D alanine look alike, D-cycloserine inhibits the formation of D-alanine dipeptide, which inhibit PG formation.

Inhibits NAM from crossing the membrane, also inhibits lipopolisaccaride synetheis in G-

Inhibit removal of Pi from C55 isoprenoid carrier lipid, the lipid carrier cannot be recycled,

the terminal D alanine need to be cut in order for the aa crossbridging to attach at the position 4 D-ala. This reaction is carried out by the transpeptidase. penicillin is a structural analogue of D-ala-D-ala. The transpeptidase binds to penicillin and become unable to remove the terminal D-ala. The end result is PG is weakened.

thiazolidine ring and beta-lactam ring are the basic structures of the penicillin. beta-lactam is the more important structure, important for activity.

1. all are bactericidal
2. only effective on actively growing bacteria (must inhibit growing peptidoglycan matrix)
3. most potent class of antibiotics (selective toxicity)

alter permeability by insertion in cell membrane through interaction with phospholipids

alter permeability by insertion in cell membrane through interactions with sterols. it's more specific for eukaryotic cells, control yeast infection.

Inhibit DNA replication by binding to DNA gyrase. DNA gyrase is composed of subunits A and B. nalidixic acid, ciprofloxacin, norfloxacin bind to subunit A. novobiocin binds to subunit B.

inhibition of DNA replication by inducing host cells to produce more free radicals. Anaerobes is more susceptible to the effect of metronidazole.

Inhibition of transcription by binding to RNA polymerase (subunit B)

Inhibition of tetrahydrofolic acid (folic acid - vit B9 or M) synthesis by binding to enzymes required in nucleic acid synthesis. Toxic to humans.

quinolones, metronidazole, sulfonamide

ethambutol (EMB), isoniazid (INH), pyrazinamide (PZA)

tetracycline, oxytetracycline, chlorotetracycline, demeclocycline, doxycycline, minocycline

lac A: b-galactoside transacetylase
lactose -> galactose and glucose
lac Y: b-galactoside permease
transport lactose into the cell
lac Z: b-galactosidase
galactose-1P -> UDP-galactose