five taste senses

Some basic Wikipedia articles to get started

bitter

• taste § bitterness
• bitter taste evolution
• bitterant
• bittering agent
• BitterDB — a database of bitter compounds
• sensitivity to some bitter substances varies by genetics
  • phenylthiocarbamide (PTC) — one of the two chemicals that scientists use to study bitter taste variation
  • propylthiouracil (PTU) — one of the two chemicals that scientists use to study bitter taste variation
  • PTC tasting
• Category:bitter compounds
• TAS2R38 — a bitter taste receptor

across several taste senses

• gustducin — a protein found in some taste receptor cells