As we all know RBC lacks mitochondria. There are few explanations like RBC respire anaerobically so it does not require mitochondria, Since RBC does not have genome and it may not support mitochondrial survival, mitochondrial absence provide more space for oxygen to carry, etc. I would like to know more in this regard. Could anyone help me in this regard? Thanks in advance
Hi, Naveen.
Since RBC has limited life span and is anucleated, meaning that it does not do much work in the sense of biosysnthesis (replication, transcription and translation etc). No synthesis, no energy required. Major role of RBC is gas transport. And this transport is a simple diffusion that uses concentration gradient in peripheral tissues. That is another evidence for no energy is required to do the major job of RBC. Cellular movement of RBC is very passively done by heart and stream of blood. Therefore, its viability does not go forever unlike other terminally differentiated cells. Not only the nucleus and mitochondria, but also much of the cytoplasmic components are also missing. Some differences found mammals and nucleated animals may have different physiology adapted and evolved in accordance to the environments over long period.
There is a good discussion. (http://www.madsci.org/posts/archives/2000-04/955119937.Cb.r.html)
Regards.
another explanation often given is that mitos in RBCs would preferentially compete with tissues for the oxygen the RBCs carry.
RBCs have a lifespan of around 120 days as against the lifespan of cells/subcelluar components with ranges from 7 to 22 days depending on the cell type. The major function of RBCs is to carry oxygen for which the major protein hemoglobin has the important role. As we all know Hb content in blood is around 10% or so. To accommodate such large quantity of Hb the RBCs are enucleated and also mitochondria are absent. The energy requirement of RBCs is only for maintaining ionic homeostasis for which Na, K- ATPase responsible.ATP required for this proces is obtained through glycolysis.
We should remember that a teleological (purpose-based) explanation is not permitted while a teleonomic argument (mechanistic) is acceptable. One way I would ensure very low dissolved oxygen concentrations in the test tube is to purge it with nitrogen, but not good enough. Really good lowering occurs when we add some hemoglobin to the solution. In the presence of Hb that sequesters oxygen with extreme efficiency, an obligatory oxygen requiring function becomes irrelevant. If the evolution pushes it out the organism would not suffer....but not when we push out mitochondria out of, say, the liver. Loss by evolutionary attrition that gains space for Hb could be the logical sequence.
Most red blood cells organelles (including the nucleus) are expelled during maturation. ... By getting rid of most organelles, space for more hemoglobin (Hb is a pretty big molecule) is freed up, for oxygen to bind to. RBC energy is supplied from glycolysis.
It seems that - at least in this thread - one has to define
which "RBC's lack mitochondria" in fact are meant.
Why?
cf.:
https://www.researchgate.net/post/Do_non-mammalian_erythrocytes_possess_mitochondria
and - eventually - read also
IUBMBLife,63(7): 560–565, July 2011
Research Communication
Red Blood Cell Extrudes Nucleus and Mitochondria Against Oxidative Stress
by Zhong-Wei Zhang, et al. 2011 =
Article Red Blood Cell Extrudes Nucleus and Mitochondria Against Oxi...
which originally is displayed at:
https:__//iubmb.onlinelibrary.wiley.com/doi/pdf/10.1002/iub.490 (delete underline character in between https: and //iubmb. ...
So - finally - it might be anticipated that the original statement should have read:
"...As we all know mammalian RBC lacks mitochondria. ..."
another reference for mitochondria in Frog's RBC's:
https://www.jstor.org/stable/3571300?seq=1 (cf: Introduction, and from their cionclusions: " Evidence was obtained for the presence of mitochondria in frog red blood cells. These organelles were distinguished by their internal trabecular ultrastructure. ..."
Teleological arguments are not valid as an explanation. The question of why camels and chicken RBC have a nucleus ( regardless of their level of expression /functionality) is very valid and functional arguments are not valid unless there is a decided advantage such as RBC volume and flexibility in negotiating capillaries and degree of oxygen carrying capacity. I am not aware of such an information.