Gel Electrophoresis and DNA Profiling

DNA Profiling

 A genetic tool used to compare and contrast DNA of different individuals.

 Compares the STRs

 

DNA profiling

 DNA profiling examines short tandem repeats (STRs) within an individual’s genome to determine how similar it is to another individual’s genome.

 STRs contain repeats of a short (2-5bp) sequence; e.g. GAGAGAGA

DNA profiling

 DNA profiling is carried out by isolation of DNA from cells (e.g. cheek cells), PCR amplification of the region containing the repeats, then gel electrophoresis to examine the size of bands.

What is Gel electrophoresis?

Is a technique that is used to separate proteins or fragments of DNA according to size

 

Step 1: The process of Gel Electrophoresis

1.DNA is extracted from a source

 Amplified by PCR

 Cut into fragments.

Step 2: The process of Gel Electrophoresis

2. DNA fragments are placed in a well within a gel

 Loading dye is added to the samples to make the DNA visible on the gel

 Buffer solution is added to the gel

 Electric current is passed through gel

 DNA fragments are negatively charged

 Move to positive electrode

Step 3: The process of Gel Electrophoresis

3.  DNA pieces separate, forming bands within the gel.

 smaller protein/DNA pieces moving through the gel at a faster rate than larger ones

 separates DNA into bands

 Bands are analysed