Bacterial Growth and Metabolism Flashcards
- Know conditions that affect bacterial growth rate - Describe a typical bacterial growth curve - Define siderophore and bacterial biofilm - Distinguish aerobic from anaerobic growth - Define normal flora and recall benefits and hazards of colonization - Recall principle of normal flora of various tissues - Define Key terms associated with infectious disease (48 cards)
How do bacteria replicate
binary fission
In binary fission, what happens in the cell?
- disruption of peptidoglycan cell wall
- replication of bacterial genome
- segregation to form daughter cells
- establishment of new ends (septa) to cytoplasmic (outer) membrane
Growth rate of bacteria depends on?
- nutrients available
- pH
- salinity (salt content)
- temperature
Prototroph can ____________?
synthesize all essential metabolites
What do auxotroph need for cell survival?
need to obtain essential metabolites from the environment. (cannot synthesize their own because they have acquired mutations in synthesizing essential metabolites.
Normally, Acidic or basic pH inhibits bacterial growth?
Acidic, low pH in certain tissues and organs prevent growth
What bacteria can overcome the acidic environment?
How?
Helicobacter pylori, H. pylori
secrete urease that converts urea to ammonia and bicarbonate –> establish infection in the gastric tract to cause ulcers
High or low salt concentration in the environment inhibits growth?
High! there are some that are resistant too.
Human pathogens are classified as ?
meophiles, because they grow optimally between 30 -37 degree Celsius.
What nutrient impacts the rate of cell division?
Iron, it is important to growth and virulence (capability to cause disease)
How does the human body sequester free iron in the blood?
by transferin and lactoferrin, iron-binding proteins –> significant defense against infection
What must happen for bacteria to colonize the host?
counter the iron limitations
How do bacteria counter iron limitations?
secreting siderophores which chelate irons and then ACTIVELY transport into the cell
How are bacteria measured in liquid culture?
Growing aliquot(portion of total ) of the culture on agar medium as the aliquots are taken at various times after broth inoculation.
What is an alternative way to measure growth of bacteria ?
Measure turbidity (cloudiness) of the liquid culture over time. As bacteria multiply, they cloud the broth and measured using spectrophotometer.
Why is there no growth immediately after inoculation of the liquid culture?
LAG PHASE
What happens in lag phase?
bacteria are adapting to new nutrient environment, reprogramming gene expression.
Bacteria replication is constant and at an optimal doubling times in what phase
Exponential Phase
What happens in the exponential phase in the cell?
maximal DNA and protein synthesis
What phase is most sensitive to antibiotic therapy?
exponential (logarithmic phase)
When is a good time to gram stain organism?
exponential phase
What is a consequence of exponential growth?
depletion of nutrients and accumulation of wastes
Describe the stationary phase
metabolism is reduced, rate of cell division is equal to the rate of cell death. Thus, no net increase in the number of viable cells.
When do gram positive bacteria initiate sporulation?
stationary phase
