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Learning Goal - DNA Replication - Applications of polymerase chain reaction and gel electrophoresis

Q: What is an application of the PCR?

Testing for coronaviruses , where the nose swab is rinsed off in a saline solution to dissolve any viral particles/viral RNA that may be present. In the case of an infected person, the RNA present is converted to DNA using the enzyme reverse transcriptase. The DNA is then put into the PCR, as it amplifies specific viral base sequences that are present and attaches fluorescent markers to them. After going through about 35 cycles of this, if the level of fluorescence rises above the benchmark, the individual is tested positive.

4 important questions on Learning Goal - DNA Replication - Applications of polymerase chain reaction and gel electrophoresis

Outline the process of DNA profiling.

This is a process that is centred on the matching of the size and number of short tandem repeats (STRs) between two or more individuals to find out about relatedness, forensic profiling etc. A child inherits two STR alleles - 1 from each parent. These STRs are basically composed of a repeating sequence of a specific base sequence (e.g. CTAG). An individual may have any number of repeats of a specific STR, but will definitely share it in common with their parents, resulting in those specific gene sequences falling into the same band in a gel electrophoresis testing, proving relatedness.

List the applications of DNA profiling.

In the IB, the main applications we need to know are forensic testing (matching of and individual's DNA to a crime scene suspect's) and paternity testing (matching a child's DNA with an individual's to see if he may be the father) --> basically matching a DNA sample to another to check if the STRs correlate in terms of number and size.

What is an example source of a DNA that can be used in DNA profiling?

STRs.

What is an application of the PCR?

Testing for coronaviruses, where the nose swab is rinsed off in a saline solution to dissolve any viral particles/viral RNA that may be present. In the case of an infected person, the RNA present is converted to DNA using the enzyme reverse transcriptase. The DNA is then put into the PCR, as it amplifies specific viral base sequences that are present and attaches fluorescent markers to them. After going through about 35 cycles of this, if the level of fluorescence rises above the benchmark, the individual is tested positive.

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Biology HL

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