Table 2 Rxn Time started Time stopped Elapsed time sec 2810 2820 2200 2170 1660 940 2820 2717 2170 2755 2655 2108 46 50 47 10 37 00 36 40 28 20 16 30 48 00 46 32 37 40 47 40 46 15 37 18 A420nm Activity A420nm time 1000 0 01 0 04 0 24 0 13 0 15 0 54 0 03 0 05 0 59 0 11 0 09 0 37 0 00356 0 0142 0 11 0 06 0 09 0 57 0 011 0 02 0 27 0 04 0 034 0 18 0 00 0 10 0 20 0 30 0 40 0 50 1 00 1 15 1 30 1 45 2 00 2 10 1a 1b 1c 2a 2b 2c 3a 3b 3c 4a 4b 4c Table 4 Rxn Time started 1 2 3 4 0 00 0 00 0 00 0 00 Time stopped Elapsed time sec 6289 1750 1 44 49 29 10 52 00 26 00 3120 1560 A420nm 0 05 0 01 0 01 0 09 Activity A420nm time 1000 0 0080 0 0057 0 0032 0 058 2 Under what conditions is the LacZ gene expressed Is there any sign of activation or repression Be sure to refer to your results when discussing your answer The LacZ gene is expressed only when lactose is present and glucose is absent With no glucose the bacteria resorts to lactose to feed on so it doesn t starve and thus the LacZ gene must be expressed so the bacteria can adjust its genes to eat lactose However even if lactose is present while glucose is as well the bacteria will feed on glucose because it prefers the high energy glucose provides It s also important to note that energy will not be wasted on expressing a gene if there is no need to express it in the first place There is a sign of activation happening which can be seen by looking at the graph On the graph the Lactose E coli culture has an activity of 0 57 at a volume of 200 L This is the highest activity number out of all the data points which means that the bacteria is very effective in this environment and therefore indicates the occurrence of activation There is also a sign of repression which can be seen at the lowest data point At reaction 1a there is an activity of 0 00356 which occurs at 20 L of the No Sugar E coli culture condition Throughout the whole graph the No sugar E coli culture condition data remains the lowest compared to the other culture conditions This is because there is no sugar present whatsoever for the bacteria to feed on not even lactose It is obvious that repression happens here as the LacZ gene is not expressed resulting in no transcription Repression happens through the process of a repressor protein binding to an operator protein in the absence of an inducer protein On the other hand If the LacZ gene was expressed then transcription would have happened as the lactose would have bonded to the repressor protein 3 Examine your data for Lab Activity 2 Describe the data and your interpretation of what you see Based on my data for Lab Activity 2 reaction 1 No Sugars E coli 20 Lactose had an activity of 0 0080 reaction 2 Glucose E coli 20 Lactose had an activity of 0 0057 reaction 3 No Sugars E coli 20 Glucose had an activity of 0 0032 and lastly reaction 4 Lactose E coli 20 Glucose had an activity of 0 058 The bacteria had the highest activity with the culture condition of Lactose E coli 20 Glucose The bacteria had the lowest activity with the culture condition of No sugars E coli 20 Glucose My interpretation of this data is that based on the activity levels the bacteria was the most effective when more lactose was present rather than glucose since the LacZ gene was expressed This makes sense as glucose cannot bind to the repressor protein like lactose can Therefore glucose prevents the transcription of the LacZ gene while lactose allows the transcription
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