DNA Profiling and Biotechnology Study Notes

DNA Profiling and Biotechnology

Introduction to DNA Profiling

  • Focus on biotechnology, specifically DNA profiling.

  • Simulation of lab work due to lack of actual equipment.

  • Overview of background, mechanism, and applications of DNA profiling.

Applications of DNA Profiling

Crime Scene Investigation

  • Primary reason for DNA profiling: to aid in crime scene investigations.

  • Various uses include:

    • Identifying a body found at a crime scene.

    • Incriminating a suspect linked to the crime scene.

  • Limitations:

    • Need to compare DNA samples from crime scenes with a known database.

    • If an individual's DNA is not in the database, identification is not possible.

Paternity Testing

  • Another significant application is to identify the parents of an individual using DNA profiling.

Mechanism of DNA Profiling

DNA Similarity Among Individuals

  • Humans share about 99.9% of their DNA with each other.

    • Despite this high similarity, the remaining 0.1% accounts for unique genetic differences.

Targeting Hyper Variable Regions

  • To pinpoint unique DNA characteristics, we focus on specific regions of the genome known as hyper variable regions.

  • These regions have been mapped within the human genome.

  • Hyper variable regions are crucial for differentiating individuals.

Short Tandem Repeats (STR)

Definition of STR

  • STR stands for short tandem repeats.

  • STRs consist of short segments of nucleotides, usually between four and eight, that are repeated multiple times.

    • Example: Repeated sequence “ta” three times (

    • Structure: ta-ta-ta.

    • Classification based on the number of repeats.

Inheritance of STRs

  • Every individual has two chromosomes for each gene, inherited from both mother and father.

    • Example of inheritance:

    • If the first chromosome has three repeats of “ta,” the second might have a different number of repeats.

  • Term used:

    • Locus: refers to a specific position on a chromosome where an STR is located.

Analysis of STRs in DNA Profiling

  • Collecting data from multiple loci allows for the construction of a unique DNA profile for an individual.

  • The standard practice now involves analyzing 22 different regions of DNA.

  • Importance of non-coding regions (often referred to as "junk DNA") analyzed

    • These regions do not code for proteins but are crucial for identity differentiation.

Conclusion and Next Steps

  • The lecture will proceed to discuss methods for targeting and analyzing these unique DNA regions.

  • Emphasis on extracting and examining the specific applicable DNA regions to confirm identities through profiling.