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Writing Lab Report 1 Standard Curve Analysis for DNA Quantitation.

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Presentation on theme: "Writing Lab Report 1 Standard Curve Analysis for DNA Quantitation."— Presentation transcript:

1 Writing Lab Report 1 Standard Curve Analysis for DNA Quantitation

2 Contents of Lab Report 1  Cover Page  Results  Text  Two Figures (graphs) with proper captions  One Table with a proper caption  Discussion  For each figure and table provide a(n)  Data Analysis  Error Analysis  Conclusion identifying the relationships observed in the data analysis

3 Cover Page  Your name  Names of your lab partners  Lab Section  Date

4 Results: Text  Briefly describe what each figure and table represents  introduce the reader to the order in which you are presenting the data  use an objective description that explains what you expect the reader to notice about the data  do not interpret the data in this section  do not provide error analysis  You may briefly explain the pattern observed in the data and/or refer to the relationship indicated by the shape of each graph. Use the descriptions in the Lab Manual section “How to Write a Scientific Report” pages

5 Results: Figure 1  Use Excel to plot the absorbance values at each concentration for YOUR GROUP’S data  Superimpose a smooth trendline  Record the equation of the trendline to present in the caption and use in calculations for Table 1  Label the axes appropriately, indicating the x and y variables and their units of measure

6 Also for Figure 1  Provide a caption below the figure  title  brief description, that can include  source of the data  relationship observed, including equation for trendline  how the figure will be used in the results and/or discussion sections

7 Example of Figure 1 with Dr. Colavito’s Data Obtained in Summer 2010

8 Example of Figure 1 with Data Obtained in Summer 2010 Adding a Trendline Be sure to copy the trendline equation and save it to use later. For the line on this grapy: y = x ; R 2 =

9 Example of Figure 1 with Data Obtained in Summer 2010 Adding a Caption I am the title of this PowerPoint slide, not the title of the graph. Do not copy my format in your lab report! I am the title for this figure. Follow my format but use your own words. I am the description for this figure caption. Yours will be more specific to the experiment you performed, of course. Figure 1: Standard Curve of Methylene Blue Absorbance. Absorbance values were obtained for dilutions of a 0.01% methylene blue solution. The equation for the trendline is y = x ; R2 =

10 Results: Figure 2  For CLASS DATA, use Excel to plot the mean values for absorbance at each concentration  Superimpose a smooth trendline (reporting the equation for this trendline is optional)  Use the standard deviation values for Vertical (Y) error bars  Label the axes appropriately, indicating the x and y variables and their units of measure  Provide a caption below the figure, including  Title  Brief description

11 Example of Figure 2 with Data Obtained in Summer 2010

12 Example of Figure 2 with Data Obtained in Summer 2010 Adding Error Bars Each error bar shows the range of +1SD from the mean value.

13 Results: Table 1  Determine the total yield of YOUR DNA EXTRACTION and show the process by providing the information for Columns 2-7 from Table 2 in the lab instructions  Use any table format that clearly shows the results  Showing the calculations is optional  Provide a caption above the table, including  Title  Brief Description: This description should include the calculated value of the mean + 1 standard deviation for DNA Yield, using the class data.

14 Data to present in Table 1 (taken from Table 2 of Lab Instructions) Absorbance reading for 5 mL solution containing methylene blue-stained DNA from one strawberry DNA extraction Weight (g) Abs 550 for Methylene Blue-stained DNA solution Concentration of Solution (%) (from standard curve) Concentration of DNA (micrograms/mL) Total Amount of DNA Recovered (micrograms) DNA Yield (micrograms DNA/gram strawberry) 25

15 Using the Standard Curve in Figure 1 to determine the percentage of methylene blue corresponding to the DNA solution Substitute 1.1 for the y value in the trendline equation: y = x ; x=0.0081%

16 Data to present in Table 1 (taken from Table 2 of Lab Instructions) Weight (g) Abs 550 for Methylene Blue-stained DNA solution Concentration of Solution (%) (from group’s standard curve) Concentration of DNA (micrograms/mL) Total Amount of DNA Recovered (micrograms) DNA Yield (micrograms DNA/gram strawberry) For Column 5: Use conversion factor shown below: 0.001% = % Z = 0.70 micrograms/milliliter micrograms/milliliter Z 0.70 For Column 6: Correct for 5 ml total volume micrograms/milliliter x 5 milliliters = 3.5 micrograms 3.5 For Column 7: Divide by the starting weight of the strawberry. 3.5 micrograms/25 grams = 0.14 micrograms DNA/grams strawberry

17 Discussion: Data Analysis  See Lab Manual Instructions for specific questions to consider in analyzing the data  For Figure 1, state the line/curve shape that you proposed and then explain WHY the line/curve would be this shape. Be sure to consider the mathematical relationship illustrated by the line/curve shape. Your goal is to address the MECHANISM by which this relationship occurs.  For Figure 2, discuss how well the data fit the proposed line/curve. Does the range shown by the data points + error bars overlap the best fit line? If your data fit the proposed line/curve shape, TENTATIVELY accept the mechanism as an explanation for the observed relationship.

18 Discussion: Data Analysis  For Table 1, consider the usefulness of the standard curve in quantifying the DNA extracted from strawberries. Address the specificity of the protocol in isolating DNA. Describe whether your individual DNA yield is reasonable in comparison to the class data.

19 Discussion: Error Analysis  Be BRIEF  Suggest sources that match both the direction and magnitude of the error  If deviation of data points from the curve or line is not large, do NOT suggest major sources of error.  At least two sources of error should be identified, one should be systematic error, the other should be intrinsic (random) error  Indicate which sources of error are specific to each figure/table presented

20 Conclusion  Write one (or a few) brief statement(s) that summarizes the relationship(s) observed between the variables that you studied  Comment on the variation observed for the class data

21 Collaboration  You may DISCUSS any aspects of your lab report with fellow students and/or your instructor  You must PRODUCE the figures and WRITE your lab report independently  Any unusual similarities will be addressed according to the SMC Code of Academic Conduct. Everyone involved will lose full credit for their reports. There are no makeups for lab reports showing academic dishonesty.


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