Question

How does rbc get energy at the abscence of mitochondria?

Answer 1

Mammalian red blood cells also lose their mitochondriaduring erythropoiesis at phase 3, when normoblasts eject organelles. Functional red blood cells produce energy by fermentation, via anaerobic glycolysis of glucose followed by lactic acid production. ... The lack of mitochondria is pivotal in this.

Answer 2

Mammal red blood cells (erythrocytes) contain neither nucleus nor mitochondria. Traditional theory suggests that the presence of a nucleus would prevent big nucleated erythrocytes to squeeze through these small capillaries. However, nucleus is too small to hinder erythrocyte deformation. And, there is no sound reason to abandon mitochondria for the living cells. Here, what latest research found that mammal erythrocyte reactive oxygen species (ROS) levels kept stable under diabetes, ischemia reperfusion, and malaria conditions or in vitro sugar/heme treatments, whereas bird erythrocyte (In contrast to mammals, RBCs in birds, reptiles and other "lower" vertebrates have a nucleus) ROS levels increased dramatically in these circumstances. Nuclear and mitochondrial extrusion may help mammal erythrocytes to better adapt to high-sugar and high-heme conditions by limiting ROS generation.

As a result not containing mitochondria, these cells use none of the oxygen they transport; instead they produce the energy carrier ATP from glucose by a glycolysis pathway that ends with lactic acid production. Furthermore, red blood cells do not have an insulin receptor and thus their glucose uptake is not regulated by insulin. Because of the lack of nuclei and organelles, mature red blood cells do not contain DNA and cannot synthesize any RNA, and consequently cannot divide and have limited repair capabilities.