$DNA$ fingerprinting is a technique used to identify individuals by their genetic makeup. It relies on the fact that the sequence of nucleotides in $DNA$ is unique to every individual,except for identical twins. The process involves isolating $DNA$,fragmenting it using restriction enzymes,separating the fragments via gel electrophoresis,and then using probes to visualize specific patterns ($DNA$ profiles). Uses: $1$. Forensic investigations for solving crimes. $2$. Determining paternity or maternity. $3$. Identifying genetic disorders and hereditary diseases.

(A) $DNA$ fingerprinting is a powerful tool in molecular biology. The steps involved are:
$1$. Isolation of $DNA$ from the sample (e.g.,blood,hair,skin).
$2$. Digestion of $DNA$ using restriction endonucleases to create fragments of varying lengths.
$3$. Separation of these fragments by gel electrophoresis based on size.
$4$. Transfer of separated fragments to a membrane (Southern blotting).
$5$. Hybridization with radioactive or fluorescent probes that bind to specific sequences.
$6$. Detection of the pattern using $X$-ray film (autoradiography),which produces a unique band pattern for each individual.
Applications:
- Forensic Science: Used to match $DNA$ samples from crime scenes with suspects.
- Paternity Testing: Used to establish biological relationships between parents and children.
- Medical Diagnosis: Identifying genetic markers for hereditary diseases.