2025 NSTA Philadelphia • EDVOTEK® Workshops

Color Your Classroom: Engaging Students with Bacteria and Bio-Art

Experimental Results and Analysis

DATA COLLECTION 1. Observe the results you obtained on your transformation and control plates.

Control Plates: (-) DNA • -DNA • -DNA/+Amp

Transformation Plates: (+) DNA • +DNA/+Amp • +DNA/+Amp/+IPTG

2 Draw and describe what you observe. For each of the plates, record the following:

• How much bacterial growth do you observe? Determine a count. • What color are the bacteria? • Why do different members of your class have different transformation efficien - cies? • If you did not get any results, what factors could be attributed to this fact?

DETERMINATION OF TRANSFORMATION EFFICIENCY Transformation efficiency is a quantitative determination of the number of cells transformed per 1 µg of plasmid DNA. In essence, it is an indicator of the success of the transformation experi- ment.

You will calculate the transformation efficiency using the data collected from your experiment.

1. Count the number of colonies on the plate that is labeled: +DNA/+Amp/+IPTG

A convenient method to keep track of counted colonies is to mark each colony with a lab marking pen on the outside of the plate.

2. Determine the transformation efficiency using the following formula:

final vol at recovery (mL)

Number of transformants

Number of transformants per µg

=

x

vol plated (mL)

µg of DNA

EXAMPLE: Assume you observed 40 colonies: 40 transformants 0.5 mL

QUICK REFERENCE:

50 ng (0.05 µg) of DNA is used. The final volume at recovery is 0.50 mL The volume plated is 0.25 mL

1600 (1.6 x 10 3 ) transformants per µg

x

=

0.05 µg

0.25 mL

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