Explain why RBC doesn't contain nucleus?
Red blood cells have adapted this characteristic (no nucleus) for several reasons.
It simply allows the red blood cell to have more hemoglobin. The more hemoglobin you have, the more oxygen molecules you can carry. Therefore, it allows RBC to transfer more oxygen.
- Lack of nucleus in RBC also allows the cell to have an unique bi concave shape that helps with diffusion.
Only RBCs don't have nucleus. All other types of blood cells have nucleus.
The nucleus is actually the control center of a cell. It has DNA in it which is required for reproduction of any cell. However, the function of RBCs is very simple. They just carry chemicals around. A RBC has haemoglobin in it which carries oxygen. The RBCs don't need to reproduce as simply more RBCs can be produced by the red bone marrow in a process called erythropoesis.
Also, they don't need any energy for transport as they're carried by the arteries and veins.
Besides, nucleus takes up a lot of space in a cell. And since RBCs don't actually do any of the functions which are nucleus's responsibility, evolution figured it out that it's more logical to just exclude them from the RBCs.
This space can be used to fit in more haemoglobin.
Hence, to carry oxygen more efficiently, RBCs don't have a nucleus.