Mini Exam 5 Flashcards
Generation time
Doubling time; how long it takes for cells to divide (ex: human cells [HeLa] have a generation time of 24 hours/1440 minutes)
Serial dilutions
Serially dilute a culture iteratively, plate cells, count colonies, multiply by dilution factor
(Ex: 1:1 —> 1:10—>1:100)
Colony forming units (CFUs)
of viable cells in original sample; calculated as CFU/mL
Mycobacterium tuberculosis
- mycolic acid on cell surface make it stain Gram +/- (helps them survive tho)
- rod shaped, aerobic
- infects lungs, respiratory disease
- resistant to desiccation (dry)
- droplet spread
According to this plate, how many viable cells were in the original culture?
16 (colonies counted) x 10^4 CFU/mL
Filtration
Enrichment of cells by filtering through a membrane with pores smaller than bacteria (opposite of serial dilution; not enough present in sample)
- 0.2 micrometers usually used
Microscope counting
Optical density
Sepsis vs Asepsis
Sepsis = bacterial contamination
Asepsis = no (sig) contamination
Sterilization
Complete removal of ALL microbes
- commercial = all DANGEROUS microbes and spores
Sanitation
Reduce number of bacteria to SAFE levels
Antisepsis
Disinfection of LIVE tissue
Disinfection
destroy all VEGETATIVE microbes
-stat vs -cide
Stat = stop growth
Cide = kill
Death curve, D-value
Log10 rate of microbe death in responde to germicide
D-value = Decimal reducing time, reduce by 90%
