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DNA Profiling using Short Tandem Repeats

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What is Short Tandum Repeat (STR) and why do we now use that for DNA profiling instead of RFLP? Why is STR more effective and more sensitive?

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In the following I have explained STR and RFLP is details. I have also attached PowerPoint slides for better understanding the concept.

99.9% of the human DNA sequences are same in every person but there is also a considerable amount of DNA that is different between people. DNA profiling technique exploits this variance to discriminate between different individuals. In the year 1986, Sir Alec Jeffreys of the University of Leicester discovered this technique of DNA profiling.

Modern DNA profiling uses Short Tandem Repeats (STR) composed of repeated units of 2-8 repeats of nucleotides located in non-coding regions of chromosomes. STR loci (locations on a chromosome) among closely related persons are very similar but unrelated humans have extremely variable STRs. PCR primers are used to target these STR sequences and they are amplified. After amplification the STRs are loaded into an electrophoresis gel and run using opposite voltages. A particular pattern of DNA bands is formed in the gel, which is unique for a particular individual. This DNA banding pattern is like a person's unique fingerprint.

Advantages of STR analysis:
1. Each and every STR is polymorphic i.e. a particular type of STR has different sequence repeats (nucleotide repeats) in different individuals.
2. Different types of STRs can be used to compare between different individuals. For example a DNA ...

Solution Summary

DNA profiling is done these days using Short Tandem Repeats (STR) technology which has replaced the previous Restriction fragment length polymorphism (RFLP) technique. The article here describes the advantages of STR technique over RFLP.

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DNA Profiling Technology

A man and his wife were on vacation in Paris. On the way back to the hotel, they were approached by two men with weapons who demanded their jewelry. A physical interaction occurred in which the robbers violently wrestled the man to the ground and removed his watch and rings while his wife tried to run away. The man and his wife were shot and killed. The bodies of the two victims were pulled into an alley. Multiple scratches were on the body of the male victim, and blood was also found on the female victim because the robbers tore the necklace, rings, and earrings off that she was wearing. The two men committing the crime both had previous records for assault and robbery. How were the men convicted of the crime?
Address the following
What exactly is DNA profiling? Explain in detail.
How it is used to solve crimes? Explain in detail.
Regarding the case above:
What physical evidence would be retrieved from the crime scene?
Identify each item of physical evidence, and fully justify your decision to collect it as evidence.
What type(s) of DNA tests are required to investigate the crime you have chosen? Explain in detail, and fully support your argument.
What is the testing process for the technique(s) used to test each piece of evidence? Be specific, and explain in detail.
After analyzing the evidence, explain how the evidence convicted the suspects.
Be sure to reference all sources using APA style.

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