Enumeration/Titer & Phage

Question 1

Why is ot important to know # of microbes in environment

Answer 1

Safety for human consumption/use

Question 2

Methods for counting of bacteria and virus

Answer 2

Spectrophotometers
Counting chambers
Serial dilutions

Question 3

Spectrophotometer

Answer 3

Light to measure concentration of number of particles in solution (how much light is absorbed/transmitted)

Beer’s law = higher amount of light absorbed, higher # of particles

Cannot determine if cells dead/alive

Question 4

Chambers

Answer 4

Glass slides with calibrated grids to determine # of cells

Cannot determine if dead/alive

Question 5

Serial Dilution

Answer 5

Diluting culture step/step
Dilute w/ media, incubate - plates examined for colonies or plaques

Number of viable cells in culture

Dilute by factor of 10

Question 6

Bacteroophages

Answer 6

Viruses that attack and replicate only in bacteria

Question 7

What triggers phages to release

Answer 7

Dormant until temp change/signals

Question 8

Components of virus

Answer 8

Head w/ DNA

Helical Sheath

Question 9

Calculations of CFU / PFU

Answer 9

of colonies or plaques x dilution factor / 1 mL

Question 10

Vortex

Answer 10

Mix/homogeneous mixture - no clumps

Question 11

Cannot reuse pipettes

Answer 11

Increased carryover - impacting colonies

Question 12

HIV is

Answer 12

Lysogenic / latency