Cells Without Nucleus: 9 Facts You Should Know


It is not possible for a eukaryotic cell to exist without nucleus but still there are some exceptions. Let us explore more about the cells without nucleus.

There are a number of cells which exist in nature without nucleus. All prokaryotes, mammalian RBCs, sieve tube elements of plant and platelets are devoid of nucleus.

Prokaryotic organisms do not contain a nucleus because their genetic material is found free in the cytoplasm and surrounded by the structure called nucleoid. Other cells like RBC, sieve tube element and platelets lose their nucleus for better functioning.

Do All Cells Have a Nucleus ?

Nucleus is one of the largest cell organelle that controls the entire cell activity. Let us see if all cells are composed of a nucleus.

All cells except prokaryotes contain nucleus like plants, animals, fungi and protists. If a cell is eukaryotic it must have a nucleus but there are some exceptions in higher eukaryotic organisms which do not possess nucleus.

Which cells do not have a nucleus?

There are number of cells that do not have nucleus. Lets us explore more about them.

Cells of hair, nail, RBC and cornified skin cells usually do not have nucleus. Before the maturity, they possess nucleus but after they become mature, they loses the nucleus so that they can perform the specialized functions of the body.

Like RBCs, cells of hair and nails also uses the nuclei for the maturation process. After maturation, they loses the nucleus in order to create maximum space by filling the cell gap with a protein called keratin.

The cornified cells do not carry out any biochemical processes. But they still provide the structural strength to other body tissues.

Why cells do not have a nucleus?

Nucleus is necessary for the cell as it controls the gene expression and other metabolic activities. Let us find out the reasons why cells do not have a nucleus.

Some cells do not have nucleus in order to function efficiently. For example, cells of RBC usually loses its nucleus to grasp more hemoglobin to carry more oxygen molecules. RBC of mammals usually posses nucleus at the beginning of their maturity. As the cells mature, they shatter their nuclei.

Without a nucleus, neither can a cell repair itself, nor can they produce energy aerobically. Being devoid of nucleus, cells function gets limited and cannot divide. RBC cells are therefore produced from the precursors in the bone marrow.

How does cell function without nucleus?

Nucleus is the control centre of a cell which regulates most of the cell activity. Let us explore, how the cell function without nucleus.

Prokaryotic cell functions without nucleus with the aid of an extranuclear DNA which controls the cellular activity. In humans, RBC transports the oxygen molecules from lungs to the body tissues with the help of hemoglobin.

Cells of RBC have to travel in small capillaries. Its bi-concave shape helps to provide more area for gas exchange. However, it is not possible for nucleated cells to do that. The life span of a cell without nucleus is very short. For example, RBC have life span of about 120 days.

Examples of cells without nucleus.

There are many cells in nature which exist without nucleus but their lifespan is very short. Let us have a look at some examples of cells without nucleus.

Prokaryotic cells, mammalian erythrocytes, sieve tube element of plant cell, cells of skin and hair are the examples of cells without nucleus. Platelets are not considered as true cells because of the deficiency of the nucleus. Platelets are basically formed from the megakaryocytes in the bone marrow.

Platelets help in clotting and are released from the bone marrow. Platelets are formed by fragmentation of huge nucleus of bone marrow. A single megakaryocyte can produce up to 1000-3000 platelets.

Does eukaryotic cell survive without nucleus?

There are some exceptions of eukaryotic cell which exist without nucleus. Let us find some more facts about the survival of eukaryotic cells without nucleus.

Eukaryotic cells survives well without nucleus but their lifespan becomes quite short as compared to those having nucleus. The reason behind the short lifespan is, nucleus helps in cell division and regulates the gene expression of the cell which ultimately increases the life span.

But in eukaryotes, if a cell is devoid of nucleus, they cannot replicate or synthesize proteins. And  if the synthesis occurs, the protein so formed can be incorrect because nucleus transcribes the proper information.

Do blood cells have a nucleus?

Blood is a reservoir of many types of cells like WBC, RBC and platelets. Let us find out which blood cell have nucleus in them.

White blood cells contains nucleus while Red blood cells are devoid of nucleus. The reason for white blood cells having nucleus is simple because they are involved in the immune response. The red blood cells loses its nucleus at the maturity and this is an adaptation of the cell to perform its function.

White blood cells do not perform mitosis or divide in bloodstream. All types of white blood cells contains nucleus and are able to make RNA and synthesize proteins. They are highly differentiated for their specific role.

Does white blood cell have nucleus?

White blood cells are divided into Granulocytes (having granules) and Agranulocytes. Let us explore more about the nucleus of white blood cells.

White blood cell are nucleated. All leucocytes are nucleated and are specialized for their functions. The nucleus of Neutrophil is multi-lobed and are connected with the help of nuclear material. Eosinophils have dumbell shaped nucleus. Basophil has S-shaped nucleus which can be multi-lobed.

cells without nucleus
Types of Leucocytes from Wikipedia

The nucleus of Lymphocytes covers almost all the part of cytoplasm. Lymphocytes are much smaller in size compared to all three granulocytes.  Monocytes are one of the largest leucocytes and their nucleus is U-shaped. These monocytes turns out to be macrophages when leaves the blood stream and are phagocytic in nature.

Which animal cell has no nucleus?

Animal cells are eukaryotic in nature and all eukaryotes posses nucleus for better functioning of the cell. Let us find out the exceptions of animal cells that lack nucleus.

The blood cells of animals like RBC and platelets, cells of hair, nail and cornified skin cells are deficient of nucleus. These nucleus deficient cells play a crucial role in the functioning of an organism and it is a kind of adaptation to them.

However, platelets are not true cells but they are one of the main composition of the blood. They can be considered as cells because of the presence of some organelle like mitochondria and endoplasmic reticulum.

Conclusion

To wrap up this post, we can conclude that if a cell is deficient of nucleus, it can still survive and  perform the functions as well. But the lifespan will be short as nucleus controls the gene expression.

Saif Ali

Hi, I am Saif Ali. I obtained my Master's degree in Microbiology and have one year of research experience in water microbiology from  National Institute of Hydrology, Roorkee. Antibiotic resistant microorganisms and soil bacteria, particularly PGPR, are my areas of interest and expertise. Currently, I'm focused on developing antibiotic alternatives. I'm always trying to discover new things from my surroundings.  My goal is to provide readers with easy-to-understand microbiology articles. If you have a bug, treat it with caution and avoid using antibiotics to combat SUPERBUGS. Let's connect via LinkedIn:http://linkedin.com/in/saif-ali-80b5098b

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