PCR Applications and COVID-19 Testing

Genotyping with PCR and Restriction Enzymes

Homozygous Recessive: Individuals with two copies of a recessive mutation will not have their DNA cut by the restriction enzyme. The DNA fragment will appear the same size as the original PCR product.
Heterozygous: Most individuals are likely heterozygous, possessing one copy of the uncut DNA and one copy of the cut DNA.
Genotyping: PCR allows genotyping by observing DNA fragment sizes after restriction enzyme digestion.

Genetic Panels: Genetic panels, whether for individuals or children, utilize a process analogous to PCR.
Process Overview: A sample is taken, the region of interest is amplified using PCR, and genotypes are distinguished based on DNA sequence variations.
High-Throughput Methods: More efficient methods exist for analyzing DNA. PCR is still the foundation.
Ubiquity of PCR: PCR is the initial step for any DNA analysis or manipulation due to its specificity and the small amount of starting material required.

PCR-based Testing: During the pandemic, COVID-19 testing relied on PCR.
Sample Collection: A brush was used to collect samples from the nose.
Sample Composition: The nasal sample contained bacteria, viruses, and cells.
Specificity Requirement: The test needed to differentiate the target virus from the numerous organisms present in the sample.
PCR Primers: PCR primers were designed to be specific to the viral DNA (or RNA).
- These primers only interact with the DNA/RNA of the virus being targeted.
- They do not interact with human DNA or the DNA of other organisms in the nose.
Positive Result: A band appears if the virus DNA is present, indicating a positive result.
Negative Result: No band appears if the virus DNA is absent because the primers are not complementary to any other DNA in the sample.
Ubiquitous Use: PCR is the starting point for any DNA-related application.

PCR Steps and Mechanism: Understand the steps of PCR and the function of the enzyme used.

Note

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