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BioBuilding: Synthetic Biology for Teachers: Lab 1: Difference between revisions
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BioBuilding: Synthetic Biology for Teachers: Lab 1 (view source)
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[[Image:Note mini.png]]''<font color = red> TEACHERS: ''If the entire growth curve (i.e. days 3, 4 and 5) is to be done in one class, you may have to start the early time points in advance. If you are dividing the growth curve into several short lab periods, be sure to store the cells in the fridge (~4°) until the next session. </font><br> | [[Image:Note mini.png]]''<font color = red> TEACHERS: ''If the entire growth curve (i.e. days 3, 4 and 5) is to be done in one class, you may have to start the early time points in advance. If you are dividing the growth curve into several short lab periods, be sure to store the cells in the fridge (~4°) until the next session. </font><br> | ||
=====Procedure, if no spectrophotometer is available===== | =====Procedure, if no spectrophotometer is available===== | ||
The turbidity of the bacterial populations can be estimated using the [http://www.microbiol.org/white.papers/WP.OD.htm McFarland Turbidity Scale]. This method uses suspensions of a 1% BaCl<sub>2</sub> in 1% H<sub>2</sub>SO<sub>4</sub> that are visually similar to suspensions of various populations of ''E. coli.''<br>[[Image:Turbidity_photo.jpg|thumb| | The turbidity of the bacterial populations can be estimated using the [http://www.microbiol.org/white.papers/WP.OD.htm McFarland Turbidity Scale]. This method uses suspensions of a 1% BaCl<sub>2</sub> in 1% H<sub>2</sub>SO<sub>4</sub> that are visually similar to suspensions of various populations of ''E. coli.''<br>[[Image:Turbidity_photo.jpg|thumb|center|400px| Turbidity comparisons for some bacterial cultures (left) and McFarland standards (right)]]<br style="clear:both" /> | ||
1. Following your teacher's instructions, obtain small clear test tubes containing the turbidity standards. The tubes should contain enough standard in each to fill the tube to a height of about 1 inch (2.5 cm) from the bottom. Make sure each tube is properly labeled with its turbidity standard number. If you are filling the tubes from stock bottles of the standards, use small tubes and place enough standard in each to fill the tube to a height of about 1 inch (2.5 cm) from the bottom.<br> | 1. Following your teacher's instructions, obtain small clear test tubes containing the turbidity standards. The tubes should contain enough standard in each to fill the tube to a height of about 1 inch (2.5 cm) from the bottom. Make sure each tube is properly labeled with its turbidity standard number. If you are filling the tubes from stock bottles of the standards, use small tubes and place enough standard in each to fill the tube to a height of about 1 inch (2.5 cm) from the bottom.<br> | ||
[[Image:Note mini.png]]''<font color = red> TEACHERS: ''The size of the tubes and the volume of sample and standard used is flexible. The important things are that the volume can obscure the thick black lines and that the samples and standards are prepared in the same fashion, as shown in the photo. </font color><br> | [[Image:Note mini.png]]''<font color = red> TEACHERS: ''The size of the tubes and the volume of sample and standard used is flexible. The important things are that the volume can obscure the thick black lines and that the samples and standards are prepared in the same fashion, as shown in the photo. </font color><br> | ||
