For many years, students who have occupied my Molecular Biology course have now applied for lab tech jobs exact after graduation. But I have NEVER had a student fail to obtain a job before graduation. One purpose for this is that my all students learn to create solutions. Four problems are here which you could remain off the unemployed college graduate list.

a) You obtain an optical density reading of a DNA sample but this is too concentrated to provide you an accurate reading. You obtain 1 μL of the DNA sample and dilute this with 14 μL of dH₂O. You after that take a reading of the DNA onto the spectrophotometer and this provide you an OD reading of 0.123. As written above the spectrophotometer is such above conversion factor: 1 OD of ds DNA = 50 μg/mL of DNA.

Question: Determine the concentration of your original DNA sample?

b) You require preparing a few solutions for a Southern blot. You are provided 50X SSC, 10 percent SDS as well as 5 M NaOH.

Question: Explain how would you make 250 mL of a solution those final concentrations were 1X SSC, 0.25 percent w/v SDS and 10 mM NaOH? When FW of NaOH is 40.0.