Latest AAB Molecular Diagnostics Testing Exam

This DNA amplification method amplifies the nucleic acid used as a probe? - ANSWER Ligase Chain Reaction (LCR) What enzymes are used in Ligase Chain Reactions? - ANSWER DNA polymerase and DNA ligase What is the function of DNA polymerase in Ligase Chain Reaction? - ANSWER Is used to initiate DNA polymerase. What is the key advantage of using Ligase Chain Reaction instead of Polymerase Chain Reaction? - ANSWER Better specificity How does Ligase Chain Reaction differ from Polymerase Chain Reaction? - ANSWER This method uses a thermostable ligase to join to probes which are then amplified by standard PCR cycling. Why was Ligase Chain Reaction originally developed? - ANSWER To detect point mutation. What do positive controls ensure during PCR testing? - ANSWER That the enzyme is active, the buffer is optimal, the primers are priming the correct sequence, and that the thermal cycler is working properly. What is a reagent blank control in PCR? - ANSWER A negative control that lacks DNA to ensure that the reaction mix is not contaminated with DNA template or amplified products from a previous run. What is a negative template control in PCR? - ANSWER A negative control that contains DNA that lacks this target DNA sequence. This ensures that the primers are not annealing to unintended DNA sequences. What is the purpose of the amplification control in PCR? - ANSWER To distinguish between a true negative for the sample and an amplification failure (false negative). What is the major source of contamination in PCR testing? - ANSWER Amplicons from previous runs. What is a method for removing nucleotides and primers from PCR products prior to sequencing? - ANSWER Shrimp alkaline phosphatase (SAP) and exonuclease I (ExoI) How does nested PCR increase both specificity and sensitivity? - ANSWER By using two pairs of primers to amplify a single target in two separate PCR runs. The second pair of primers bind slightly inside the binding sites of the first pair. This will increase the intended PCR product. How does PCR differ from qPCR (real time)? - ANSWER PCR detects the final product by endpoint analysis. How does qPCR differ from PCR? - ANSWER qPCR detects the quantity of product as it is produced during the run. What is the purpose of the quencher in qPCR? - ANSWER To reduce the florescence signal. What are three common molecular tests that involve the amplification of probe sequences? - ANSWER Ligase Chain Reaction (LCR), Strand Displacement Amplification (SDA), and Q-beta Replicase. What is isothermal amplification? - ANSWER A process that uses one temperature for amplification after the initial denaturation. The major amplification products in Strand Displacement Amplification (SDA) is? - ANSWER Probes/Primers Strand Displacement Amplification (SDA) was first widely used to detect which organism? - ANSWER Mycobacterium tuberculosis Where does Q-beta Replicase derives its name? - ANSWER From the major enzyme that is used to amplify the probe sequence (Q-beta replicase) What is Q-beta Replicase? - ANSWER A RNA-dependent RNA polymerase Why are signal amplification tests better for quantifying the amount of target sequence in a sample? - ANSWER Because the number of target sequences are not amplified. What are three signal amplification techniques? - ANSWER Branched DNA Amplification (bDNA), Cleavage-Based Amplification, and Cycling Probe.