Explain how the structure of a goblet cell is related to its function in the digestive tract.

IB DP Biology Standard Level (2023 syllabus) — B2.3 Cell specialisation · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Goblet cells are unicellular glands found interspersed among the epithelial lining of the small and large intestines. They are highly specialised secretory cells.

Model answer (4 marks)

1. Goblet cells produce mucus (glycoproteins/mucins) that lubricates the intestinal lining, protecting it from mechanical damage and digestive enzymes.
2. They contain an extensive Golgi apparatus, which packages and modifies mucin glycoproteins into secretory vesicles ready for exocytosis.
3. They possess abundant rough endoplasmic reticulum, synthesising the large quantities of mucin proteins required for continuous secretion.
4. The apical region is expanded and filled with mucin‑containing secretory vesicles, giving the characteristic goblet shape and allowing large volumes of mucus to be released by exocytosis at the luminal surface.

Examiner tips

  • Use the exact terms ‘mucus’, ‘glycoproteins/mucins’, ‘Golgi apparatus’, ‘rough endoplasmic reticulum’, and ‘exocytosis’.
  • Show the link between structure (Golgi, rER, vesicles) and function (continuous mucus secretion).
  • Keep each point brief and to the point to fit the 4‑mark format.

Common mistakes

  • Confusing goblet cells with other glandular cells or omitting the Golgi apparatus.
  • Failing to mention the apical expansion or the role of exocytosis.

Mark scheme (4 marks)

  1. Goblet cells produce and secrete mucus (glycoproteins/mucins), which lubricates the intestinal lining to protect it from mechanical damage and digestive enzymes.
  2. Goblet cells contain an extensive Golgi apparatus, which packages and modifies mucin glycoproteins into secretory vesicles ready for exocytosis.
  3. Goblet cells possess abundant rough endoplasmic reticulum (rER), which synthesises the large quantities of mucin proteins required for continuous secretion.
  4. The apical region of goblet cells is expanded and filled with mucin-containing secretory vesicles (giving the characteristic goblet shape), allowing large volumes of mucus to be released by exocytosis at the luminal surface.

Key terms in this question

goblet cell

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