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Explain cell and its different parts?
A cell is the smallest structural and functional unit which retains the characteristics of life. Cells are widely different from each other in shape and size, but each cell is determined by its unique characteristic features. Despite the many differences, every cell has three essential components – a cell membrane, the cytoplasm, and the nucleus.
Cell Membrane
A cell membrane makes up the boundary of the cell and separates it from the external environment. It is a porous structure that protects and maintains the shape of the cell. The pores in the cell membrane allow the substances to move in and out of the cell. The cell membrane encloses the cytoplasm and the nucleus.
Just like humans, the plant cells also have a cell membrane. However, plant cells have an extra supporting layer outside it, called the cell wall. The cell wall is a thick layer made of cellulose. It provides shape and mechanical strength to the plant cells, thus enabling plants to withstand harsh climatic conditions.
Cytoplasm
The cytoplasm is a transparent, jelly-like substance that fills the space inside a cell. It helps to keep the cell alive by providing necessary nutrients. The cytoplasm has several subcellular structures known as cellular organelles, for example, the nucleus, mitochondria, Golgi bodies, endoplasmic reticulum, and many more.
Nucleus
The nucleus is a large, central controlling unit of the cell. It has a double-layered, discontinuous, porous membrane called the nuclear membrane. The pores of the nuclear membrane are known as nuclear pores.
Nucleus has other structures such as –
DNA: DNA (Deoxyribonucleic acid) is the genetic material present inside the nucleus. It is a long, thread-like densely coded structure which regulates various cellular activities. DNA in all our cells put together would be about twice the diameter of the Solar System.
Chromosome: Chromosomes are thread-like structures. They are condensed forms of DNA and are visible only when they divide. Chromosomes carry genes.
Gene: A gene is a functional segment of DNA. Genes help in transferring hereditary characteristics from parents to offsprings.
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