Edexcel A Level (IAL) Biology -6.19 DNA Profiling- Study Notes- New Syllabus

DNA Profiling: Identification & Genetic Relationships

🌱 Introduction

DNA profiling (or DNA fingerprinting) identifies individuals or determines genetic relationships based on unique DNA sequences. No two individuals (except identical twins) have exactly the same DNA.

🟣 How DNA Profiling Works

Sample Collection

• Obtain DNA from blood, hair, skin, saliva, plant tissue, or other cells.

DNA Extraction

• Cells are lysed and DNA is purified from other cellular material.

Amplification (PCR)

• Specific DNA regions are copied multiple times to ensure sufficient material.

Fragment Separation (Gel Electrophoresis)

• DNA fragments are separated by size using gel electrophoresis.
• DNA ladder allows estimation of fragment lengths.

Visualization & Comparison

• DNA bands are visualized with staining or fluorescent dyes.
• Band patterns are compared between individuals or species.

🔵 Applications

• Identification of Individuals
  • Forensics: match crime scene DNA with suspects.
  • Paternity testing: compare child and parent DNA bands.
  • Conservation biology: identify individuals in a population.
• Determining Genetic Relationships
  • Compare DNA band patterns between species or populations.
  • Close relatives share more similar DNA patterns.
  • Used in parentage confirmation, evolutionary studies, and breeding programs.

🟢 Key Features

• Highly specific – focuses on variable regions like short tandem repeats (STRs) or microsatellites.
• Non-coding regions often used because they vary more between individuals.
• Requires only small DNA samples.
• Can be matched against DNA databases for identification or population studies.

📋 Summary Table