Question

Nerve cells do not divide because they do not have
A. Nucleus
B. Centrosome
C. Golgi body
D. Mitochondria

Answer 1

Hint: Neurons mostly have similar organelles as in other somatic cells. They differentiate for their ability to conduct electrical signals. Also, neurons do not divide due to the absence of rod-like structures called centrioles. These structures are responsible for spindle formation that is necessary for cell division.

Complete answer: Neurons are the basic functional unit of the brain that receive signals from the environment and conduct them through other neurons towards the brain. These electrical signals along with chemical signals are processed in the brain. The brain is capable of remembering an exposure to a particular stimulus. Neurons present in adults are formed during infancy and at the gestation period. No neurons are added in the brain after a certain period and the existing ones do not divide. This allows for a stable interneuronal connection between neurons and allows neurons to make a memory of an incidence. A dividing cell must contain rod-like structures called centrioles which are present in the centrosome. Centrosomes are small organelles present beside the nucleus of the cell. The centrioles in the centrosome initiate spindle formation for cell division to take place. Neurons lack this organelle and hence, lack centrioles. This is the reason they cannot divide. The inability of neurons to divide and make new neuronal cells makes it difficult for brain injuries to recover. Scientists are looking for a way they can initiate division in damaged brain cells. Neural stem cells hold a promise to be a cure for brain injuries. The hippocampus of the brain is known to have some dividing neuronal stem cells.
Hence, option B is the correct answer.

Note: Inability of neurons to divide is regarded as non-beneficial, but it has a functional significance. New cells in the nervous system would not prove good as the whole nervous system is based on interneuronal connections. Adding extra or new neurons would make a mess with already well-established connections, which may interfere with the functionality and stored information in the neurons.