Comparing Frog Gels: Analysis of Male and Female Samples Jorge Bermudez Kathleen Cadman Nernie Tam

b The objective of the following analysis is to determine whether or not the sizes of extractable skin polypeptides vary with regard to the sex of the specimens. Frog Gel Analysis Four samples were used--two 7.5% gels (one male, one female), and two 12% gels (also male and female).

Methods Used b Using Adobe Photoshop, we lined each individual sample up with a ruler and measured the distances between each polypeptide band. b The bands were indicated by periodic darkening of the blue stain. b Each measurement was recorded in a table using Microsoft Excel.

Calculations To extrapolate results from our data we first needed to decide which model best represented it. Using Excel, we applied three standard models to our male and female standards, and also to the experimental data that best paralleled the standards. I. Linear (a + bx) II. Quadratic (a + bx + cx^2) III. Cubic (a + bx + cx^2 + dx^3) We also applied one non-standard model: IV. Non-standard (a + bx + c(ln(x)) The standard models were:

I. The Linear Model When the linear model is applied, the accuracy measurements for the 7.5% samples are as follows:

The accuracy measurements for the 12% samples are as follows:

II. The Quadratic Model When the quadratic model is applied, the accuracy measurements for the 7.5% samples are as follows:

The accuracy measurements for the 12% samples are as follows:

III. The Cubic Model When the quadratic model is applied, the accuracy measurements for the 7.5% samples are as follows:

The accuracy measurements for the 12% samples were as follows:

IV. The Non-Standard Model The 7.5% Samples: The 12% Samples:

Choosing a Model Next we consider the order of the models. The lowest is the most efficient. In examing the applications of the various models to our data, it becomes obvious that the cubic model is the most efficient. The cubic model, particularly when applied to the 7.5% samples, has the lowest S*T-value, and therefore the most precise margins of error. Now that we have decided upon a model, we can move on to comparing male and female samples.

Analysis: Male and Female Samples Given the time constraints, our final analysis of the data was somewhat more abbreviated than our process for choosing a model. We observed that there was a difference between males and females with relation to the number of extractable polypeptides: more were extracted from the female samples. Again, given the time limit, we were unable to determine whether the sizes of the polypeptides varied according to sex. Had the due-date been postponed, we would have actually applied the model and obtained values for the samples’ molecular weights.

The 12% gel concentration produced better results. With the higher concentration, the polypeptides experienced less mobility, allowing for greater visibility for the lighter stains in the gel. Because the 7.5% gel allowed the polypeptides greater mobility, they tended to collect at the bottoms near the dye fronts, making them harder to differentiate.

Error Analysis (This is the part of the presentation where we make excuses for our incompetence.) Our calculations were probably the most accurate part of the analysis. It is highly probable that any errors resulted from the initial collection of the data. Our estimations of the relative mobility of the polypeptide bands is--in all likelihood--riddled with human error.

In Conclusion... For this particular analysis, the cubic model was the most efficient. When it comes to the number of extractable polypeptides, female samples are superior.

In Order of Appearance: Nernie Tam Jorge Bermudez Kathleen Cadman