# BIOB11H3 Lecture Notes - Lecture 3: Diluent, Flight Controller

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Published on 8 Oct 2019
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You will work in pairs. Since it is impossible to follow an entire growth curve in a 3-hour lab period, most
of your measurements will involve only the exponential and (perhaps) lag phases. To use your laboratory
time efficiently and effectively, there are several things you must do ahead of time.
1. Read the procedures very carefully and be sure that you understand what has to be done.
2. Practice calculating dilutions.
3. Prepare you data tables (i.e. those below) so that you can fill in the data as you track the bacterial
growth.
Table 1: Turbidimetric growth results (Do Not allow the tables to split between pages when preparing
the Lab Report)
Tube
Growth
time (min)
Dilution
Dilution Factor (DF)
Observed
OD600
Undiluted OD
(calculation)
1
0
2
20
3
40
4
60
5
80
6
100
7
120
Table 2: Plate count results
Tube
Growth time
(min)
Final plated
Dilution
Final plated
DF
Number of
Colonies
1
0
2
20
3
40
4
60
5
80
6
100
7
120
THE MATERIALS AND PROCEDURES FOR TURBIDITY AND PLATE COUNT MEASUREMENTS (EXERCISES 1
AND 2 RESPECTIVELY) WILL BE DESCRIBED SEPARATELY BUT WHILE YOU ARE PERFOMING THAT LAB, YOU
WILL COLLECT SAMPLES FOR BOTH TYPES OF MEASUREMENTS AT THE SAME TIME. THE PLATE COUNT
STEPS CAN BE CARRIED OUT IN INTERVALS AFTER THE TURBIDIMETRIC SAMPLING AND READINGS.
NOTE: Dilution Factor = Final volume / Solute volume
Example: You want to make a 1:5 dilution of a culture in a final volume of 5 ml Using this formula, you
would ultimately add 1 ml of your culture to 4 ml of diluent (e.g., LB broth or 0.95% saline solution).
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