Molecular Basis of Inheritance : DNA Profiling : Brief History and Satellite DNA

The technique of DNA Profiling is based on sequencing 0.1 % DNA which is unique in each individual . This technique was developed by Alec Jeffreys in 1984 . It's a technique used to identify living things based on their DNA by looking at unique patterns in their DNA

1. DNA FINGERPRINTING (DNA PROFILING) BIOLOGY- LET’S SIMPLIFY

2. DNA FINGERPRINTING : BRIEF HISTORY Also called DNA Profiling or Genetic Fingerprinting . Developed by- Alec Jeffreys in 1984 Used to identify living things based on samples of their DNA, by looking at unique patterns .

3. IMPORTANT FACTS 99.9% DNA base sequences are identical in every individual .( B ulk genomic DNA ) Only 0.1% DNA base sequences are different. Exception – monozygotic twins. (single zygote) Types of repeat seq . used in DNA Profiling- 1 . VNTRs – Variable Number Tandem Repeats. 2. STRs – Short Tandem Repeats.

4. SATELLITE DNA H ighly repetitive non coding DNA O ften  found  near   centromere, telomere , heterochromatic area. Density  differs from  bulk genomic  DNA . Separated as Satellite from bulk DNA using Density Gradient Centrifugation .

5. SATELLITE DNA TYPES Microsatellite Minisatellite Short tandem repeats that consist of 1 to 9 base pairs monomer repeating sequences. Tandem repeats with a  monomer repeat length of 10 to 100 base pairs. Rich with A and T bases. Rich with G and C bases. Also known as simple sequence repeats (SSR) or short tandem repeats (STR). Also known as variable number tandem repeats (VNTR).

6. DNA PROFILING STEPS DNA ISOLATION PCR : DNA AMPLIFICATION CUTTING : RESTRICTION ENZYMES SORTING : GEL ELECTROPHORESIS SOUTHERN BLOTTING PROBING : RADIOACTIVE DNA PROBE X- RAY FILM EXPOSURE