RBCs do not have nuclei. Discuss its advantage.
Topic: Red blood cells — absence of nucleus
Answer
- It leaves MORE SPACE for HAEMOGLOBIN, so each red cell can carry more oxygen.
- It allows the cell to take up its BICONCAVE shape, which increases the SURFACE AREA for faster exchange of gases and lets the cell bend to squeeze through narrow capillaries.
Two marks, so give TWO advantages.
The mature mammalian red cell loses its nucleus as it develops, and every feature of the cell follows from that: the space freed up is filled with HAEMOGLOBIN, so the cell becomes essentially a bag of oxygen-carrying pigment without a nucleus bulging in the centre, the cell can be BICONCAVE — dished on both sides — which gives a larger surface area for the same volume, and makes it flexible enough to bend through capillaries narrower than itself
THE COST of this efficiency, worth a closing line: with no nucleus the cell cannot repair itself or divide, so it lives only about 120 days and is then destroyed in the spleen — which is why the spleen is called the graveyard of RBCs.