PEPTIDES (Syllabus: GS Paper 3 - Sci & Tech

News-CRUX-10     25th July 2023        

Context: The immune systems of fruit flies develop certain genes that can combat common bacteria found in food, a new study has found.

Key Points

  • Bacteria such as acetobacter found in fruits can harm flies once they exit the gut and reach the bloodstream. 
  • However, various fly species have developed a specific peptide (strings of compounds that combine to form proteins) that can fight acetobacter.
  • The findings are critical as fruit flies’ evolutionary process might help explain human susceptibility to certain diseases.
  • The bacteria in their food and environment mould the immune systems of fruit flies. 
  • These flies have developed two peptides to defend a single bacterial species that affects them.
  • Some of these peptides are common in certain species.
  • Various fly species have developed a particular peptide (diptericin B) to control acetobacter.
  • Glial cells and neurons in the fly brain communicate, dampening olfaction and shielding the animals from consuming the pathogen again after an intestinal bacterial infection.


  • Peptides are short chains of amino acids linked tide bonds.
  • A polypeptide is a longer, continuous, unbranched peptide chain.
  • Polypeptides which have a molecular mass of 10,000 Da or more are called proteins.
  • Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides.
  • Peptides can perform interactions with proteins and other macromolecules
  • They are responsible for several important function in human cells, such as cell signaling and act as immune modulators