Question

Purpose:
In this laboratory you will carry out a quantitative real-time PCR (QPCR), using SYBR Green, on the samples that you purified last laboratory session. QPCR serves several purposes in a forensic laboratory and is included in the sample processing workflow for all/most DNA samples. QPCR ultimately measures (either in absolute numbers or relatively) the amount of DNA in a sample and the presence of any inhibitors (either partial or complete). This allows the forensic scientist to determine if more purification is needed, to remove inhibitors, and how much sample to add to the STR PCR to individualise the sample.

SYBR Green is a fluorescent dye that binds double stranded DNA and sits in the minor grove of DNA. This property is the reason that SYBR Green will not bind single stranded (or denatured) DNA. QPCR works by incorporating SYBR Green into a PCR and detecting the fluorescence after each cycle of amplification. As the number of amplicons (sections of DNA copied during PCR) increase, there will be more double stranded DNA, more SYBR Green will bind, and the fluorescence will increase. The signal of the fluorescence is predictable based on the amount, in either ng or copy number, of DNA present, although a DNA standard series needs to be incorporated to every run to ensure accuracy in this measurement. By using a standard series of known DNA concentrations, unknown samples can then be compared and a starting concentration value for those unknowns can be determined.

Need help with 'introduction and aims' part.

What is the purpose of the experiment? What technique are you using? Why is it appropriate? (1 paragraph)

Answer 1

Aim/Purpose

To analyse the DNA content or expression of a particular gene in a sample .

The technique used in the experiment is Quantitative PCR . This technique is suitable in this case becase , usuing a normal PCR for analysing these samples will not give the exact quantity of the DNA, whereas in QPCR a dye called SYBR green binds to the groves of the DNA and gives fluorescence , this light is captured by the system to quantify the DNA. The most important is that the dye binds only to double stranded DNA and thereby it is precise. By using a control DNA with a known concentration the concentration of the unknwon sample is known. This system efficiently works by splitting its functions into 4 distinct phases such as linear ground phase, early exponential phase,log phase and plateau phase. Diving the functions into these distinct phases would make the results more accurate.