DNA Analysis Fundamentals
Ever wonder how crime scene investigators identify whose blood was at a scene? DNA analysis makes it possible! The process begins with DNA digestion, where genetic material is cut into fragments that create unique patterns for each person.
Gel electrophoresis is the key technique that separates these DNA fragments based on their size and electrical charge. Think of the gel like a molecular sieve - smaller DNA pieces travel further through the gel's porous structure than larger pieces. The gel contains agarose (a mixture of agar and buffer solution) that acts as this filter.
During the process, DNA fragments move through the gel when an electric current is applied. Since DNA has a negative charge, it naturally migrates toward the positive pole. After separation, the gel is stained with a special dye that makes the DNA visible, creating a DNA profile - a pattern as unique as a fingerprint.
Quick Tip: DNA can't be extracted from mature red blood cells (erythrocytes) because they don't contain a nucleus! Investigators must use other blood components for DNA analysis.
