A nucleus is membrane enclosed organelle that is present within a cell. Let us discuss more about the nucleus in detail below.
Almost all the cells contains the nucleus. However, certain types of cells in the body lacks a nucleus for example red blood cells. RBCs do not have nucleus and are called as enucleated cells that enables them to have enough room for the oxygen and hemoglobin transport.
Nucleus is one of the important organelle found in the eukaryotic cells. The nucleus is formed by the assembly of vesicles which fuses together to form membranes around chromosomes.
The vesicles and the chromosomes together forms a nucleus. The nucleus undergoes cleavage with every cell division which divides the nucleus into two nuclei.
Types of Nucleus in tissue cell
There are certain types of nucleus that are found in the cells. Let us discuss more on the types of nucleus below.
- Uninucleate cell: These are the monokaryotic plant cells which possess only a single nucleus.
- Bi-nucleate cell: These are the dikaryotic cells containing two nucleuses at once. Examples of bi-nucleate cells include, paramecium, balantidium, Liver cells, and Cartilage cells.
- Multinucleate cells: These are polynucleate cells which possess more than two nucleus at the same time. Examples of these cells include, latex cells and latex vessels in plants, bone marrow cells and striated muscle cells in animals.
- Enucleate cells: These are the cells that do not possess any nucleus. Examples of these cells include mature sieve tubes of phloem in plants and red blood cells in animals.
The cells are named based on the number of nuclei they possess. These cells with more than one nucleus are formed due to fusion with each other for example, multinucleated giant cells are formed by the fusion of monocytes and macrophages.
Structure of nucleus in tissue cells
Nucleus provides integrity to the structure of a cell and regulates most of the biological process taking place inside it. Let us discuss the structure of nucleus in detail.
A sphere-shaped nucleus is found in the tissue cells of all eukaryotes. Nucleus in tissue cells is surrounded by a membrane which consists of pores that are involved in selectively transporting the solutes in and out of the nucleus.
The nuclear membrane creates a separation between the cell cytoplasm and the internal environment of the nucleus.
Parts of a Nucleus
A nucleus contain four parts, such as nuclear membrane, chromatin threads, nuclear sap, nucleolus. Let us discuss the parts of nucleus in detail.
- Nuclear membrane: It consists of two-unit membranes, the outer membrane and the inner membrane. Both membranes are formed of lipoproteins, consist of pores, have a perinuclear space in between and inside contains dense lamella.
- Chromatin threads: Chromatin threads are intertwined and forms a network which is known as chromatin reticulum. During the process of cell division, the threads unwind and at this stage they are called chromosomes.
- Nuclear Sap: Nuclear sap is also known as nucleoplasm and consists of nucleoproteins, organic and inorganic molecules such as, minerals, ribose sugars, enzymes, nucleotides, phosphorus, etc.
- Nucleolus: Nucleolus is also known as the storage house for RNA. It is known to be disappeared in the cell cycle stage of late prophase and comes back in the stage of telophase.
Sometimes a nucleus contains more than one nucleolus, for example onion contains four nucleoli. The membrane of nucleus which is called a “nuclear membrane” contains small pores which acts as a passage for selectively transferring the molecules in and out of the nucleus.
Functions of nucleus in tissue cells
Nucleus plays a central role in many biological processes occurring inside the cells at regular intervals. Let us discuss the functions of nucleus in detail.
- Nucleus is the storage house of the chromosomes, which are the hereditary units consisting of nucleic acids and proteins called histone.
- Nucleus is the place where two important biological process takes place, these include – DNA replication and transcription (formation of RNA).
- It is also involved in other cellular activities such as synthesis of proteins, cell division, cell growth, etc.
Nucleus activates the cell activities which includes, growth of the cells, cell division, metabolism, stores the chromosomes, and provides the overall structural and functional support to the cells.
Do all tissue cells have nucleus?
Eukaryotic cells contain a double membranous nucleus and membrane bound organelles, while prokaryotic cells are the opposite. Let us discuss more about it here.
All tissue cells have a nucleus except certain cells such as RBC which lose nuclei after maturation. Due to lack of nucleus the life span of RBC is approximately 120 days. The shape of RBC is bi-concave without nucleus. The absence of nucleus in RBC is advantageous for their performance inside body.
Red blood cells function in carrying out oxygen and are able to diffuse through the blood vessels because they do not contain nucleus, which makes them flexible.
Which tissues have cells with the nuclei located at the base?
The positioning of the nucleus varies based on the cell type, usually it is oriented in the center. Let us discuss the tissue which has cells with nuclei located at the base.
Columnar epithelium is a tissue where the cells are present at the bottom and is found in the linings of stomach and intestine. The cells in columnar epithelium are elongated in shape. The nuclei present are also elongated up to the same level as in the other neighboring cells in symmetry.
Simple columnar epithelium contains an elongated nucleus. Other tissues such as squamous epithelial tissue, has cells that are flat, round and small, with the nucleus at the center.
Does epithelial tissue have a nucleus?
Epithelial tissue is a covering found on the internal and external surface of the body. Let us discuss if epithelial tissue is composed of nucleus or not.
Epithelial cells contain nucleus which is usually located at the center except in columnar epithelium cells where the nucleus is elongated and present at the base of the cells. On the other hand, squamous epithelial cells are round and flat in shape and contain a small nucleus at the center.
Smooth muscle tissues contain cells which are spindle shaped, and have a single nucleus present at the center and they also lack striations.
To conclude the article, we can say that all tissue contains a nucleus which can either be centrally located or present at the base of the cells in an elongated shape. The nucleus plays central role in various biological processes and is a storage house for chromosomes.