Cell Functioning

Plant and animal bodies are made up of small cells. The body of a living organism is made up of cells and these cells combine together to constitute a tissue. The tissues are arranged in a particular organ and the organs are distributed all over the body of the organism. A cell is called a basic functional unit of life. Each cell, whether it is a plant or animal cell is comprised of many cell organelles. Each of these cell organelles has its own function to perform in order to maintain the cellular function. The major cell organelles that are present in a cell are DNA, RNA, nucleus, nucleolus, cytoplasm, plasma membrane, endoplasmic reticulum, Golgi-complex, microtubules, Lysosomes, ribosomes and cell wall in the case of plant cell.

Nucleus consists of chromosomes which are made up of deoxyribo nucleic acid. It consists of genetic information, which is transcribed and translated into proteins. The proteins are later utilized for cellular metabolism. The structure of the chromosome changes during cell division. They get thickened when the cell is dividing and again become thin when the cell completes division. The numbers of chromosomes in the chromosome set vary with species. The nuclear membrane protects the nucleus and helps in transfer of materials from nucleus to cytoplasm. The transcribed RNA reaches the cytoplasm through nuclear membrane and the necessary proteins for transcription will be transported from the cytoplasm to nucleus. Nucleolus is another cell organelle that is visible only when the cell is not dividing. It consists of RNA, which is used for synthesis of proteins.

Centrioles are two cylindrical organelles that are arranged at right angles to each other on the cellular poles, which help in cell division. Centrioles have microtubules arranged in nine bundles with three tubules in each of the bundle. Plant cells consist of chloroplasts, which are the sites of photosynthesis. The humans depend on the process of photosynthesis occurring in plants for the purpose of food. The chlorophyll pigment inside the chloroplasts is responsible to carry out the mechanism of photosynthesis. Microtubules are also found to be giving support to the cell and act as the cytoskeleton. There is another network of tubules called endoplasmic reticulum which extend from nuclear membrane till the plasma membrane through the cytoplasm. Smooth endoplasmic reticulum helps in storage and division of the cell. It also aids in the transport system in the cell. Rough endoplasmic reticulum helps in synthesis of proteins on the ribosomes, which are attached to the endoplasmic reticulum. Golgi complex is found to be present nearer to the nuclear membrane. It helps in synthesis of secretory proteins by attaching an oligosaccharide to each of the secretory protein. Lysosomes have digestive enzymes which can digest the wastes and toxins in the cell and transport it towards the cell membrane for getting removed immediately.

Mitochondria are the organelles which aid in cellular respiration. The first cycle in respiration called glycolysis occurs in cytoplasm, the next process called Kreb's cycle occurs in mitochondrial matrix and the electron transport part occurs on the inner membrane of the mitochondria. The structures called oxysomes on the inner membrane of mitochondria are involved in electron transport and in reduction of oxygen into water. Ribosomes are the organelles that help in organizing the protein synthesis apparatus. Cell wall in plant cell is elastic enough to expand the cellular volume, when the cell becomes turgid. Plasma membrane is the cell covering which is made up of lipoproteins. The inner membrane proteins are helpful in transmission of substances across the membrane. Plasma membrane is otherwise called as selectively permeable membrane. The cell ingests the food material, digests it and sends the useful products to the blood stream. The waste materials are excreted into the blood. The waste is cleaned by the kidneys, skin and other excretory organs. These are functions of the cell in brief.

By Haripriya_Munipalli

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