What are cells and it's Components?

Cell in Biology

All living organisms are composed of one or more similar units, known as cells. This concept is important because it emphasizes the basic structural and functional sameness of all living organisms. 

In the seventeenth century, an English scientist, Robert Hook using a microscope constructed by himself, observed that cork and plant tissues are made of small cavities separated by walls. He called these cavities, "cells," which means "little rooms." However, it took scientists over 150 years to define "cell" as the basic unit of living matter.

In 1838, a German botanist, Matthias Schleiden came to the conclusion that all plant tissues contain a massive number of cells. In the following year, zoologist Theodor Schwann observed that all animal tissues are also made of cells and he proposed a cellular basis for all life. In 1858, Rudolf Virchow finally came to the conclusion that cells can arise only from preexisting cells. 

Components of Cells

The three main components of cells are: 

>> cell membrane 
>> nucleus
>> cytoplasm  

The cell membrane is a lipid bilayer structure that separates inside the cell from its surroundings and lets some molecules go in and out while preventing the others.  The cell membrane has proteins, and chlostrols embedded inside of it.  Chlostols are to give the cell membrane its strength, while proteins perform different functions mainly transporting some molecules into and out of the cells--transport proteins.  Cells can transport molecules via passive (no energy is required) or active (energy is required) transport.  

The nucleus is one of the most important parts of a cell.  It contains chromosomes, DNA, RNA, and functions as the headquarter of a cell.  The nucleus plays an important role in cell division.  

The cytoplasm is the space inside the cell.  It contains different organelles such as mitochondria (produces energy), Endoplasmic Reticulum (transports proteins), Golgi bodies (packages proteins), and ribosomes (makes proteins).