Molecular Techniques used to identify source of biological samples.

For your DNA paper, you will need to discuss how we use molecular techniques to identify the source of biological samples. You are expected to understand the protocols that we cover and the theoretical reasons behind the steps.


  • Summarize the major points of the paper.

The Abstract is a short passage that summarizes the major elements of the paper: objectives, methods, results, and conclusions.  It is typically written as a single paragraph.  In the case of published works, a good Abstract helps researchers assess the relevance of a paper to their own research, and thus decide whether or not they should read it completely.  Scanning the Abstracts of papers is also one way that scientists, when pressed for time, keep abreast of recent literature.

Although readers see the Abstract first, it is easiest to write it last, once you have a good overview of the paper.  One way to write an Abstract is to list, one by one, all the important points covered in each section of the paper.  Write complete sentences if you can.  Make successive revisions, paring the list down bit by bit, omitting peripheral topics and details, until you have revealed the “skeleton” of the study.

Introduction:  In composing the paper, it is most logical to start in a very broad sense and to become more specific as you move through. Start your paper with a very high level, overarching use of the series of techniques you have studied. For example, a paper could start with an introduction to how DNA forensics were used in O.J. Simpson’s murder case. (Do not use this example, your introduction will be graded a zero.) The opening paragraph could start with the general details of the case and that this was the first major case to use DNA forensics. The final sentence of this paragraph would lay out the techniques used in the case. This concluding sentence sets up the rest of your review paper, with each set of paragraphs detailing one of the techniques.

DNA isolation: In this section, explain what DNA isolation is and why it is important. You can elaborate on the stability of DNA and how it can be used in the introduction that you crafted. It is important that you highlight why certain chemicals were used in the extraction. Explain what the following chemicals are and why they are used in the extraction: SDS, proteinase K, guanidine chloride, and EDTA. It is important that you demonstrate that you understand the use of these chemicals, so fully explain why they are used. We employed a silica membrane-based spin column extraction technique.

Polymerase Chain Reaction:  Describe the details behind this reaction. What are the goals behind this reaction and when/why would it be done? Explain and define the following components: the enzyme, dNTPs, primers, and the buffer. Go into detail about what Taq is and why we use this enzyme. Also explain what a primer is and how we can change the primers to change the target sequence.

Gel Electrophoresis: Describe the goals of gel electrophoresis. Ensure you describe what the gel is composed of and what the buffer is made from. What role does each chemical in the gel and the buffer play? Describe the physics behind how electrophoresis works, i.e.. how size affects nucleotide migration, what charge do nucleic acids have, and how we set up the electrical field? Include the role of both the loading dye, Gel Red, and the molecular weight marker.

Sanger sequencing:  Sanger sequencing is the method of dideoxy sequencing that we use in Bio 2450. It is a modified PCR reaction that has the dNTPS replaced with a mixture of dNTPs:ddNTPs. In this section, go into detail on how the addition of ddNTP alters the produced PCR fragments and describe how we ultimately get the sequence.

Conclusion:  Finish up your paper with a strong concluding paragraph tying in the methods used and how they would tie back to the original scenario you presented in your paper.

Works Cited: There is a minimum of ten (10) peer reviewed primary references required for this paper.