Tag: introduction to cell discovery and cell theory

• Dujardin applied the name 'sarcode' to the free plasma without a covering to protect it from the contact with the outer world. So, the living things were named as a sarcode.

Rudolf Virchow famously stated "Omnis cellula e cellula", i.e., "All cells only arise from pre-existing cells."

The nucleus was discovered by Robert Brown while he was working on orchids, under a microscope and he observed an opaque area, which he called the areola or nucleus. It is a site for the genetic material.

The cell walls observed by Hooke gave no indication of the nucleus and other organelles found in most living cells. The first man to witness a live cell under a microscope was Anton van Leeuwenhoek, who in 1674 described the algae Spirogyra. 

The cell was first discovered by Robert Hooke in 1665, which can be found to be described in his book Micrographia. In this book, he gave 60 'observations' in detail of various objects under a coarse, compound microscope. One observation was from very thin slices of bottle cork. 

Cells are called as the basic unit of life because all the living organisms are made up of cells and also all the functions taking place inside the body of organisms are performed by cells. Cells provide the specific conditions, for the occurrence of the metabolic reactions. These have the specialized enzymes, which catalyze the biochemical reaction and regulates the functions of the body.

• The cell is the basic unit of life. All the living organisms are made up of cells and each cell performs a life-sustaining process. The cell is composed of the cell membrane, cytoplasm, nucleus, cell organelles and cell wall (except animal cells). An organelle is a distinct part of a cell, which has a particular structure and function. 
• Each organelle performs a particular function. For example- mitochondria produce ATPs, lysosomes digest cellular waste and debris, centrioles separates chromosomes during cell division, Ribosome synthesizes proteins, cell wall protects, etc. 
• Due to this, a cell can survive and perform its own functions. Thus, the correct answer is option A.

• Cells are called the structural and functional unit of life because all the living organisms are made up of cells and perform all life process for survival. Unicellular organisms are made up of a single cell and single-cell only performs all the functions of life. Whereas multicellular organisms are made up of multiple cells and perform all the functions of life. Thus, the correct answer is option A.

• The basic living structure of all organisms is a cell. Cell, which was discovered by Robert Hooke in the year 1665, is considered to be the basic structural and functional unit of all the organisms. 
• Many cells combine together to form a tissue. Many tissues together form an organ. Many organs form an organ system and many different organ systems together form a human body.
• So, option cell is the structural and functional unit of all organisms and so option B.