Understanding Gene and Allele

Jul 22, 2024

Gene vs. Allele

Introduction

  • Clarifying the difference between Gene and Allele.
  • Genetic terms often used interchangeably but have distinct meanings.

DNA and RNA Basics

  • DNA Structure: Double helix, twisted ladder containing base pairs (Adenine, Thymine, Cytosine, Guanine).
  • Length of DNA: Contains sections coding for multiple things, especially proteins.
  • Sequence of base pairs: Holds the information content in DNA.

Genes

  • Definition: A stretch of DNA that codes for specific proteins or functional RNA.
  • Examples:
    • Genes involved in the immune system.
    • Genes that regulate DNA replication.
    • Genes affecting pigmentation (skin, eyes, etc.).
  • Transcription and Translation:
    • DNA → pre-messenger RNA → messenger RNA (mRNA).
    • mRNA Codons: Every three base pairs form a codon, each codon codes for an Amino Acid.
    • Proteins: Sequence of amino acids bonded together.
  • RNA Functions: Not limited to coding proteins:
    • tRNA: Transports appropriate Amino Acids to mRNA in Ribosomes.
    • Ribosomal RNA (rRNA): Structural component of Ribosomes.
    • Functional RNA: RNA playing functional or structural roles.
  • Early Life Theory: Speculates life started as self-replicating RNA.

Alleles

  • Definition: Specific variations of a Gene.
  • Differences in DNA Sequences:
    • Small changes (e.g., Adenine replaced by Thymine) can be inconsequential or significant.
    • Amino acid sequence in proteins might change due to these variations.
  • Examples:
    • Eye color determination: Different Alleles can lead to blue eyes or brown eyes.
  • Inheritance of Alleles:
    • Two copies of each Gene in somatic cells (one from each parent).
    • Variants can influence traits (e.g., eye color).

Key Takeaways

  • Gene: General term for DNA regions coding for proteins/functional molecules.
  • Allele: Specific variant of a Gene, contributing to genetic diversity.

Conclusion

  • Understanding Genes and Alleles is crucial for grasping genetic complexity and variation.
  • Genetic traits are influenced by both Genes and their Allelic variations.