ExamIReviewSummer2010HandoutsBW

ExamIReviewSummer2010HandoutsBW - Lab Basics Units...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Lab Basics • Units Significant Figures Accuracy & Reproducibility /Precision • Pipeting • Spectroscopy Units • Understand Conceptually –Molar = moles/liter, moles of solute per total volum –mM, μg/aliquot –Protein Assay: mg/ml, all types [protein] –Enzyme Assay: units/ml, activity conc. –Ammonium sulfate % saturation • Not the same as % W/V • Not a concentration. Significant Figures • Report to the “highest/first” place of uncertainty. • Singlets: Instruments precision • Replicates: Reproducibility n = number or values (p. 9 in lab manual) Set of 2 values 125.2 123.1 125.2 123.1 121.2 127.4 122.8 More than 2 values Look for first place of uncertainty Average 123.94 lbs. Frequency σ - designates the range in which ~68.3% of the values fall near the average.
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
2 Significant Figures Adding/Subtracting two values (LDH LAB 3) – Add errors directly. – e.g. 10 ± 5 g + 1.0 ±0.5 g = 11 ± 5.5 • 11 ± 6 Multiplication/Division (LDH LAB 1) – Add percent errors (Conservative method) – e.g. 10 ± 1 g / 100 ± 1 ml • Both have 1% errors. Final error = 2%. • Final error: 0.1 g/ml x 2% = 0.002 g/ml • 0.100 ± 0.002 g/ml Propagation of Errors: Purification Table Multiplicative functions – percent errors. Will be helpful for progress report I. Error Propagation will not be tested on exam I. Reproducibility Accuracy Poor Good Poor Good Good Good Poor* Poor * Poor Accuracy - does not measurably hit the target! Reproducibility • Randomness: ex) technique, spec error. Corrected only by more repeats Can affect accuracy but could be corrected with more replicates. Defines optimal range in quantitative assays. Direct Spec Assay/Beer’s Law Protein Assays Standard curve Enzyme Assays optimal slopes Accuracy • Randomness ex) technique, spec error. Can be corrected with replicate measurements. Systematic Errors Each sample affected the same way. Could be corrected when recognized. Best in the optimal range of assays Systematic Error could shift optimal range.
Image of page 2
3 Systematic Shift Error or Not? Changes in time & temperature Standard curve normalizes – estb. optimal range of incubation. Error – incubated longer than hour.
Image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern