Suggested Added Readings and Activities regarding Week 5's Material

Conjugation (Sexduction) Text 282-284 (there is nothing in the lab manual)

KNOW THIS: Griffith's Transformation Experiment (Text Fig 9.23)

And these also:

Vaccines 468-476 That chapter's questions 9, 12 and 15 That chapter's concept questions 6a,b; 10a; 11a; 14a

To prepare yourself for Week 6: Text Chapter 16

Activities:

Plot your OD readings for the growth curve we made in lab.
There is good reading on this in your lab manual (pages 135-146).
Know the three types of machines that quantitatively measure turbidity (cloudiness) - colorimeter, spectrophotometer, and nephlometer. All use a photoelectric cell to measure the amount of light, but the source of the monochromatic light and the pathways are different. In a colorimeter, the light is a white lightbulb, the color is chosen by passing the light through a colored glass, and the light path is straight through the sample (transmitted light). In a spectrophotometer, the light is from a white lightbulb, the color is produced by passing the light through a prism or refraction grating and choosing a portion of the spectrum (rainbow) to use, and again the pathway is straight through (transmission). A nephlometer is like a spectrophotometer, but the pathway is that the photoelectric cell (electric eye) looks at the sample from a right angle - thus it looks at reflected light rather than transmitted light. We ourselves see mostly reflected light so our eyes are like nephlometers. ("nephlos" is Greek for clouds)

Remember "some possible" synonyms for OD (optical density): absorbance; turbidity; cloudiness. ("Some possible" only for looking at suspended bacteria, but not for dissolved colored compounds in water - those are strictly OD or absorbance, as you will see in Week #6's lab when we look at the yellowness of solutions at a wavelength of 420 nm (green light).

Most of your plate-counts grew up nicely and are being refrigerated for your counting in the next lab period. And then you will graph those also.