Question

Which of the following is anucleate?
A. Squamous epithelial cells
B. Mature human erythrocytes
C. Mature frog erythrocytes
D. Human Osteocyte

Answer 1

Hint: Anucleate are without a nucleus. In specific, this corresponds to a cell that lacks a nucleus. Prokaryotes is a simple, unicellular organism without any defined nucleus or even other membrane-bound organelles.

Complete Answer:
Red blood cells in humans are anucleate once they are matured, which implies they do not even have a cell nucleus. In contrast, the red blood cells of many other vertebrates have nuclei; the only other known exceptions are Batrachoseps salamanders and Maurolicus fish. The absence of the nucleus in vertebrate red blood cells was provided as a justification for the eventual accumulation of non-coding DNA in the genome. The claim is just as follows: efficient transport of gases enables red blood cells to move through really narrow blood vessels, and that this limits their size. In the absence of nuclear removal, the aggregation of replication sequences is constrained by the volume occupied by the nucleus that grows with the size of the genome. Nucleated red blood cells in mammals comprised of two forms: normoblasts, which have been regular erythropoietin catalysts to mature red blood cells, and megaloblasts, which have been abnormally large components to megaloblastic anaemia.
So, the correct answer is option (B).

Additional information:
According to one study, the way enucleation happens in mice would be that the actin filament ring envelops the cell, and then contracts. This cuts off a section of the nucleus-containing cell, which will then be ingested by a macrophage. Enucleation most likely tends to follow a very similar process in human beings. The actual mechanism for enucleation is uncertain. But cytoskeleton proteins are the main agents of enucleation. Most animal models that lack such proteins are not available for review, and all these animals die quickly at the embryonic period.

Note: A mature erythrocyte appears to lack the nucleus and mitochondria to create room for even more haemoglobin and thus more oxygen atoms. The absence of such organelles also inevitably leads to the peculiar biconcave looks of RBCs that aid in effective diffusion.