CDS (II) 2024 General Knowledge · Question 9 of 120

Correct — B, Lysosome. The lysosome is the only organelle in the list that carries digestive enzymes. NCERT's cell chapter introduces it as the clean-up system of the cell and describes it as a single membrane-bound sac filled with enzymes that break down unwanted proteins, carbohydrates and fats and even damaged parts of the cell, with the products released back into the cytoplasm for reuse. The same machinery handles material from outside. When a white blood cell engulfs a bacterium, the particle is taken in inside a vesicle, that vesicle fuses with a lysosome, and the enzymes inside dismantle the intruder. A lysosome holds dozens of different hydrolytic enzymes, which is why it can attack proteins, polysaccharides and lipids alike. The membrane around it matters as much as its contents: it keeps those enzymes sealed away from the rest of the cell.

• (a)Endoplasmic reticulum — The endoplasmic reticulum is a network of membranes for making and moving material. The rough part, studded with ribosomes, handles protein synthesis and transport; the smooth part makes fats. It builds molecules rather than breaking them down.
• (c)Golgi body — The Golgi body modifies, sorts and packages what the endoplasmic reticulum sends it, dispatching the products in vesicles. It is closely involved because lysosomes are formed from it, but the Golgi body itself does no digesting.
• (d)Mitochondria — Mitochondria release energy by cellular respiration and store it as ATP. Breaking down glucose to release energy is a different process from digesting foreign material, and mitochondria have no part in the second.

A eukaryotic cell divides its work among membrane-bound organelles. The endoplasmic reticulum makes and transports proteins and lipids, the Golgi body modifies and packages them, the mitochondrion releases energy by respiration, and the lysosome breaks material down. The lysosome is formed from the Golgi body, so the cell's building line and its dismantling line begin at the same place.

The item is a one-organelle-one-verb recall, and the reliable route is to fix a single verb to each name — the endoplasmic reticulum makes, the Golgi packs, the mitochondrion powers, the lysosome digests. The nickname worth carrying is the older textbook one: the lysosome is called the suicide bag of the cell, because if its membrane bursts the enzymes escape and digest the cell itself. That nickname is also the trap, because a candidate who has learnt only the nickname may associate lysosomes with cell death rather than with everyday digestion, when in fact most of their work is routine housekeeping — clearing worn-out organelles, and dismantling bacteria and other material the cell has taken in.

• NCERT describes lysosomes as single membrane-bound sacs filled with enzymes that break down unwanted proteins, carbohydrates and fats, and even damaged parts of the cell.
• A lysosome contains dozens of different hydrolytic enzymes, which is why it can attack many kinds of molecule.
• Material taken in from outside by endocytosis or phagocytosis is digested when its vesicle fuses with a lysosome — this is how a white blood cell destroys a bacterium.
• Lysosomes are formed from the Golgi body.
• If a lysosome's membrane breaks, its enzymes can digest the cell itself, which is why it is nicknamed the suicide bag of the cell.

• Attaching digestion to the mitochondrion because respiration also breaks glucose down; the two are different processes.
• Reading the suicide-bag nickname as the lysosome's main job; its routine work is housekeeping.
• Confusing the Golgi body with the lysosome — the Golgi makes the lysosome, but does not do the digesting.

Usually as a which-organelle-does-this item, or as a matching list of organelles against functions; the digestive-enzyme and suicide-bag hooks recur in both CDS and NDA.

• practice — not a real PYQ

  Lysosomes are often called the suicide bags of a cell because

  • (a)they contain the cell's genetic material
  • (b)their enzymes can digest the cell itself if their membrane breaks
  • (c)they stop the cell from taking in oxygen
  • (d)they multiply until the cell bursts

  Answer(b) their enzymes can digest the cell itself if their membrane breaks — the sac keeps powerful digestive enzymes sealed away from the rest of the cell.

• practice — not a real PYQ

  Which organelle modifies and packages the material made by the endoplasmic reticulum and dispatches it in vesicles?

  • (a)Golgi body
  • (b)Lysosome
  • (c)Ribosome
  • (d)Mitochondrion

  Answer(a) Golgi body — it modifies, sorts and packages proteins and lipids for transport or secretion, and lysosomes are formed from it.