Cell Structure and Function

Cell Structure and Function:

All living organisms are made up of cells. Cells are the building blocks of every organism’s body. These are the lowest levels of organ systems that collectively make up an organism.

Cells contain several organelles which perform specific functions for cells. Several other biomolecules like lipids, nucleic acids and proteins are also found in cells. The hereditary material of cells is also present inside the cells.

What is a Cell?

The cell is the fundamental functional unit of life which cannot be seen with the naked eye. Billions of cells are found in multicellular organisms which are of different sizes, and shapes and perform different functions.

History of Cells:

The cell was first time described by Robert Hooke in 1665 while he was studying bottle cork of the tree bark using his own compound microscope. He notices some small room-like structures in the cork and named them cells. He called the cells non-living components because he could not notice any movements in the cells due to the small magnification power of his microscope.

Cell Theory;

Cell theory was developed by the two microbiologists Schleiden and Schwann which described the following properties of cells;

• All living things are made up of cells
• New cells are developed from the division of old cells
• Cells are the basic units or building blocks of life

Modern Concept About Cells:

In 1883, Robert Brown, a Scottish botanist first described the nucleus of cells and gave the first insight into the cells.

• The activity of an organism is dependent on the activity of independent cells
  
• Energy flow in cells occurs by respiration through the breakage of carbon dioxide
  
Every cell has its hereditary information for the creation of new
• cells
  

Cell structure:

Prokaryotic and eukaryotic organisms are different from each other because prokaryotic organisms are unicellular and eukaryotic organisms are multicellular. On the other hand, animal cells are different from plant cells because animal cells do not have cell walls while plant cells do. However, some common structures found in all cells are the following;

Cell Membrane The Cell Envelop; Also known as plasma membrane, it is a selective permeable membrane that allows only selective substances to pass through it. The cell membrane provides coverage by enclosing the organelles. The cell membrane is formed of proteins, lipids and carbohydrates. It is a

semi-permeable membrane that allows the exchange of water, carbon dioxide and oxygen. It also removes toxic substances from the cells.

Nucleus- The Brain of the Cell: The nucleus is the largest cell organelle which is present in the center of the cell. The fluid present inside the nucleus is called nucleoplasma. Each nucleus has a small body inside it which is called nucleolus which prepare ribosomal RNA which are transported out of the cell through nuclear pores. The nucleus is found in all cells of the body except in red blood cells.

The nucleus contains DNA which is the genetic material of organisms and is transferred from one generation to another at the time of division.

The nucleus controls all the metabolic activities of cells, stores genetic information, manufactures protein components and helps in cell division and synthesis of RNAs.

Cytoplasm: Cytoplasm is a thick jelly-like fluid present between the cell membrane and the nucleus of cells. Organelles float in the cytoplasm. All cellular activities and functions such as protein formation, respiration, energy production, mitosis and meiosis, etc. take place in the cytoplasm.

Mitochondria Powerhouses of Cells: Mitochondria are also known as the powerhouses of cells because they generate energy for all metabolic activities of the cells. Mitochondria contain their DNA.

Endoplasmic Reticulum-The Proteins Storage Factory: The endoplasmic reticulum is bound to the nuclear membrane. These are of two types i.e. Rough Endoplasmic Reticulum and Smooth Endoplasmic Reticulum.

The rough endoplasmic reticulum is called so because it contains ribosomes on its surface. It produces vesicles for protein packaging. Smooth endoplasmic reticulum produces small amounts of lipids, proteins, and carbohydrates. It also breaks down toxic substances in the cells.

Golgi Apparatus- The Protein Packaging Factory: Golgi apparatus or Golgi bodies receive proteins from the endoplasmic reticulum, modify their structures, give them specific shapes and transfer them to specific locations where these proteins are needed.

Ribosomes-The Protein Synthesis Factory: Ribosomes are floating organelles in the cells and are also found on the rough endoplasmic reticulum. Ribosomes make essential proteins for various cellular functions therefore called protein manufacturing factories of the cells.

Lysosomes-The Suicidal Bags of the Cells: Lysosomes are small organelles in the cytoplasm of the cells that contain hydrolytic enzymes. They digest the cells after the cells’ death and destroy foreign particles such as pathogens.

The Storehouse of the Cells: vacuoles store different substances such as water, minerals, salts and food materials. These are also called the storehouses of cells.

Functions of Cell:

Cell performs the following functions such as;

• Cell provides support and structure for the whole body.
• It promotes growth by mitosis and meiosis.
• It provides energy for various metabolic functions.
• It helps in reproduction by cell division methods.
• It performs transportation functions such as transferring oxygen, nutrients and other essential substances by diffusion.
• It helps in metabolism by converting food into energy.