Question

Why do red blood cells have no nucleus?

Answer 1

Red Blood Cell carries oxygen from lungs and spreads it to every cell of our body. Then they carry Carbon dioxide from the cells to the lungs for gaseous exchange. The haemoglobin inside the Red Blood Corpuscle carries the oxygen. Haemoglobin is a protein that can be found in RBC. Red Blood Cells are also called Red Blood Corpuscles, Erythroid Cells or Erythrocytes and also Haematids.

Complete answer:
The Red Blood Cell is flexible and assumed to be bell shaped, as these cells pass through extremely small blood vessels. It is covered with a membrane composed of proteins and lipids. The biconcave shape of the Red Blood Cell does not contain organelles, not even nuclei. It contains only haemoglobin. Haemoglobin is a red iron-rich protein that binds oxygen.
The Red Blood Cells adapted this no nucleus characteristics due to some reasons –
This feature simply allows the Red Blood Corpuscle to have more haemoglobins. The more haemoglobin our blood has, the more oxygen molecules our blood can carry. Therefore, it allows the Red Blood Corpuscle or RBC to carry more oxygen.

The absence of the nucleus in the Red Blood cell also allows the cell to have a unique bi-concave shape that helps with diffusion.

Additional Information:
The Red Blood Corpuscles are produced in the bone marrow of our long bones. At the initial stage when they are produced they have a nucleus. But later when they get mature they lack the nucleus in order to accommodate more haemoglobin so that they can carry more oxygen. As much haemoglobin as our blood has, our blood gets rich in oxygen.
The Red Blood Cells are also considered as the cells though they don’t have a nucleus inside them.

Note:
Nucleus is a heavy organelle of a cell and it acquires lots of space. So, if the nucleus is removed then it makes a huge space within a cell. That’s why the mature RBC doesn’t have a nucleus, which creates a big space to accommodate more haemoglobin in it and carry lots of oxygen in our blood.