L7 DNA Typing and Profiling

• DNA is made of nucleotides: A, T, G, C

• Used to code for amino acids 

• Has a double helix structure

Total amount of DNA in a cell

DNA fingerprinting can help to detect individuals as only identical twins can have the same DNA. Identification of individuals via DNA fingerprinting is highly accurate. DNA similarity among human individuals is 99.9% and the difference is 0.01%

It can retrieved from various samples like hair, bodily fluids, skin cells, etc.,,

Restriction fragment length polymorphism (RFLP) is the term to describe the process of DNA cutting. PCR uses nucleotides and DNA polymerase to rapidly multiply copies of the cut DNA fragments.

DNA Cutting

Uses restriction enzymes to cut DNA into specific sequences with different lengths 

Polymerase Chain Reaction

Uses nucleotides and DNA polymerase to rapidly multiply copies of the cut DNA fragments 

Gel Electrophoresis 

• After cutting and amplification, DNA at a crime scene would be separated by gel electrophoresis

• Uses the negatively-charged attribute of DNA and move it to the positive pole

• Separated based on their size, bigger fragments move slower so it would be the further away from the positive pole