Question

'Cell is the basic unit of life'. Explain the statement.

Answer 1

Hint: Cell is the structural, functional, biologic unit of all organisms, the cell is the basic unit of life, and cells are also called as building blocks of life, and the study of cells is called cell biology or cytology. It contains the fundamental molecule of life, of which all living things are composed.

Complete answer:
> History
- Cells were discovered in 1665 by Robert Hooke.
- Cell theory was developed in the year 1839 by Matthias Jakob Schleiden.
- Cell theory states that every organism is made up of one or more cells, and cells are fundamental units for structure and function, cells came from pre-existing cells, and this theory also states that cells have emerged in the earth 3.5 billion years ago.
- A cell consists of a cytoplasm, enclosed by a membrane, and it also consists of proteins, nucleic acids, etc.
- Both plant and animal cells are visible only under a microscope, which ranges from 1 to 100 micrometers.

> Types of cells
- Cells are of two types, Prokaryotic which is a unicellular organism, where the nucleus is absent and nucleosome present, while eukaryotic cells, which either unicellular or multicellular consist of a nucleus.

> Components of cell
- The components of the cell are enveloped by a membrane called plasma membrane or biological membrane, which controls in and out the movement of particles and maintains the electric potential.
- Most of the cell volume is made up of cytoplasm.
- Both prokaryotes and eukaryotes consist of cell organelles, whereas in prokaryotes, they are very simple and not bound by a membrane.
- The nucleus of prokaryotes is made of either DNA or RNA.
- In eukaryotes, the nucleus consists of chromosomes, and the synthesis of DNA and RNA takes place in the nucleus only and enveloped by a nuclear membrane.
- It consists of organelles like mitochondria, Golgi apparatus, endoplasmic reticulum, Mitochondria, peroxisomes, Lysosomes, chloroplast, etc.
- Cells are multiplied either by mitosis or meiosis.
- In multicellular organisms, cells make up to form tissues, these tissues all make up to form organs, and organs to the organ system, and organ systems to organisms.
- The function of the organ system depends on the integrity of the organ.
- So the cell is considered a basic unit of life.

Note: In higher organisms like humans, all cells are mainly categorized into 4 types, which are epithelial cells, Nerve cells, muscle cells, and Connective tissue cells. Whereas the human body is totally made up of 40 trillion number of cells, out of which the human brain includes the 80 billion cells.