3-Bacterial Metabolism Flashcards
how to bacteria reprod
~binary fission~
1 cell splits into 2
reproduction steps
- genome replicate
- cell elongation
- divison septum forms
- separation
typical growth curve phases
- lag- no inc in # of cells, fed nutrients to prep for reprod
- log- exponential inc in cells, uber fast
- stationary- nutrients are used up, plateau, divisioin=death
- decline- waste products built up, exponential dec
when most sensitive to antimicrobial
lag + log phases
less sensitive to antimicrobials
stationary phase
cell density determined by?
colony counts on agar plate OR optical density
factors that determine growth
culture
- pH
- oxygen
- nutrients of media
- temp
broad classifications
- how use oxygen
- how use carbon/energy source
aerobe
-exclusively aerobic respir
-oxygen terminal electron receptor
facultative anaerobe
-use respiration or fermentation
-grow in presence or absence of oxy
anaerobe
-exclusively ferment or anaerobic
-if get oxygen then die (strict)
can be aerotolerant that not use oxy just tolerate
microaerophilic
grow best at low oxy (5-10%) but tolerate atomospheric O2 (21%)
how bacteria counteract ROS
- SOD converts superoxide to hydrogen peroxide
- catalase detoxifies hydrogen peroxide to water and oxy
enzs not present in obligate anaerobes
superoxide dismutase
aerobic energy production
most efficient energy generating mode
O2 is terminal electron acceptor
anaerobic energy production
inorganic terminal receptors (NO3, SO4)
some facultative orgs and some obligate anaerobes
fermentation energy production
organic metabolic intermediates for terminal electron receptors
least efficient
fermentation of pyruvate products
acids- if a bacteria uses sugar will result in acid
-can id bacteria based on end products pH
where folate comes from
in humans from diet (preformed)
in bacteria from para-aminobenzoic acid
need for syn of purines and thymidine
nucleic acid pathway
- DHDP + PABA (dihydropteroate diphosphate, paraaminobenzoic acid)
- DHPS enzyme (dihydropteroate synthase)
- dihydrofolic (DHF) acid
- DHFR enzyme (dihydrofolate reductase)
- tetrahydrofolic (THF) acid
- purines > DNA/RNA or thymidine > DNA
sulfonamide blocks what
DHPS enzyme
(dihydropteroate)
DHFR inhibitor blocks what
aka trimethoprim
DHFR enzyme
(dihydrofolate reductase)
replication steps
- start at origin of rep
- two replication forks in oppo directions until terminal site
topoisomerase required to unwind so can target with antibiotics
transcription and translation
happen simultaneously in cytoplasm
-ribosomes bind free 5’ end of nascent mRNA (make RNA as transcription happening)
ribosomes in translation
70S = 30S (with 16S rRNA) + 50S (with 5S and 23S rRNA)
other names for peptidoglycan layer
murein layer
cell wall
sacculus
peptidoglycan composistion
alternating NAG-NAM units
-NAG/GlcNAC, NAM/MurNAC
NAM has pentapeptide side chain
pentapeptide side chain comp
- L Ala
- D-Glu
- DAP
- D-Ala
- D-Ala
transglycosylation
lengthening peptido strands by adding units covalently linked NAG-NAM+pentapeptide
enzymes: transglycosylases
transpeptidation
peptide bond b/t 3rd position and 4th positon of adj strands
L-Lys or DAP (diamino acid) to D-Ala
by transpeptidases/penicillin binding protein (PBP)
targets for penicillins and B-lactam antibiotics
peptidoglycan synthesis
- NAG and NAM in cytoplasm
- NAM-pentapeptide made and added to bactoprenol first then NAG added
- bactoprenol lipid carrier across membrane to inner leaflet
- attachment to growing end of chain
determinant of survival
if cell membrane or not
