Pedigree Analysis, PCR & Genetic profiling (21)

Question 1

Explain the steps involved in the PCR, and give examples of applications of PCR

Answer 1

PCR steps involved
Denaturation (96°C): Heat the reaction strongly to separate, or denature, the DNA strands. This provides single-stranded template for the next step.
Annealing (55 - 65°C): Cool the reaction so the primers can bind to their complementary sequences on the single-stranded template DNA.
Extension (72°C): Raise the reaction temperatures so Taq polymerase extends the primers, synthesizing new strands of DNA.
Applications of PCR
genotyping, cloning, mutation detection, sequencing, microarrays, forensics, and paternity testing

Question 2

Explain the roles of primers in determining the specificity of PCR amplification

Answer 2

Primers are used to determine the DNA fragment to be amplified by the PCR process. … They direct replication towards each other – the extension of one primer by polymerase then becomes the template for the other, leading to an exponential increase in the target segment

Question 3

Compare and contrast PCR in a tube with DNA replication in a cell

Answer 3

PCR in a tube -
Primers are designed to amplify a specific DNA sequence.
They direct replication towards each other, the extension of ones primer by polymerase then becomes the template for the other, leading to an exponential increase in the target segment
DNA replication -
the “unzipping” of the parent molecule as the hydrogen bonds between the base pairs are broken. Once exposed, the sequence of bases on each of the separated strands serves as a template to guide the insertion of a complementary set of bases on the strand being synthesized.