Why don't red blood cells have a nucleus?

Question

Why don't red blood cells have a nucleus?

Answer 1

idk

Answer 2

in the bone marrow they have a nucleus but they lose it when they enter the blood stream, so that they can carry things more effectively.

Answer 3

In my opinion,every cells has its own functions.So, red blood cell's function is only to transport oxygen and it don't need nucleus.

Answer 4

The usual answer is "it gives more room for haemoglobin, and also allows the cell to be flexible enough to pass through narrow capillaries."

I am unconvinced by this, however. Birds have red blood cells which retain their nuclei. And birds have a higher metabolic rate than mammals, so require more oxygen.

I suppose the probable answer is that a mutation arose in a basal "proto-mammal" which resulted in RBCs losing their nuclei during differentiation. Since RBCs are terminally-differentiated, and will therefore never need to divide again anyway, the loss of the nucleus was unimportant, and so has never been selected against.

So essentially, it is a result of genetic drift and the founder effect.

Answer 5

because that way there is more space for it to carry more oxygen around.

Answer 6

In the bownmarrow they used to have one

read

http://en.wikipedia.org/wiki/Red_blood_c...

Answer 7

you can call it an adaptation. Because of their role to carry O2 to the respiring cells in the body, having no nucleus enables them to carry more O2.