Types of the PCR
Polymerase Chain Reaction
Real-Time PCR
For single stranded RNA / DNA. It produces cDNA from target sequence using reverse transcriptase.
Real Time PCR is characterized by the point in time during cycling when amplification of the PCR product of interest is first detected rather than the amount of the PCR product of interest which is accumulated at the end-point after PCR which contained a large number of cycles. Real Time PCR does this by monitoring the amount of fluorescence emitted during the PCR reaction, and this acts as an indicator of the amount of PCR amplification that occurs during each PCR cycle. Thus, in newer Real Time PCR machines, one can visually see the progress of the reaction in "real time".
Hot Start PCR
Hot Start PCR allows the inhibition of polymerase activity during PCR reaction preparation. By limiting polymerase activity prior to PCR cycling, Hot Start PCR reduces non-specific amplification and increases PCR product target yield.
PCR or polymerase chain reaction uses DNA polymerases which were isolated from thermostable organisms.
Nested PCR
Nested PCR is a variation of the polymerase chain reaction (PCR), in that two pairs of PCR primers are used to amplify a fragment.
The first pair of PCR primers amplify a fragment similar to a standard PCR. However, a second pair of primers called nested primers bind inside the first PCR product fragment to allow amplification of a second PCR product which is shorter than the first one.
The advantage of nested PCR is that if the wrong PCR fragment was amplified, the probability is quite low that the region would be amplified a second time by the second set of primers. Thus, Nested PCR is a very specific PCR amplification.
Touchdown PCR
It is another modification of conventional PCR that may result in a reduction of nonspecific amplification. It involves the use of an annealing temperature that is higher than the target optimum in early PCR cycles. The annealing temperature is decreased by 1°C every cycle or every second cycle until a specified or 'touchdown' annealing temperature is reached. The touchdown temperature is then used for the remaining number of cycles. This allows for the enrichment of the correct product over any non-specific product .
PCR-ELISA
PCR products are labeled (e.g., by digoxigenin) during amplification. A capture probe specific to the PCR amplicon is used to immobilize the amplicon to well plate. ELISA against the label (e.g., anti-digoxigenin) is then used to quantitate PCR products
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اختي سماح وجزاك الله خيرا ..... بالنسبة لاستخدامات البي سي ار فهي كثيرة مو بس الكشف عن الحمض النووي الدي ان ايه او الار ان ايه للفيروسات بل للبكتيريا او الحمض النووي للانسان خصوصا في مشاكل النسب او في علم الجريمة واذا تبي اكثر حددي مواضيعك ونساعدك ان شا الله بالبحث وفقك الله ......
Address people in the language they can understand
خاطب الناس على قدر عقولهم:sm188:
ممكن توضحلي أكثر كيف نقدر نستخدم الحمض النووي للانسان خصوصا في مشاكل النسب او في علم الجريمة يعني نعتمد على تكثير الحمض النووي ثم أكتشافه زي الفيروسات ولا الطريقه تختلف؟
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