Cell | Type of Cells | Important Fact about Cell

Cell Definition

The functional and structural unit of any organism, is called cell. The cell is a smallest unit of any organism.

• First of all Robert Hook discovered the death cell in 1665 in a thin layer of cork.
• After this A scientist named Lewen hawk studied on RBC cell, Bacteria and sperm cell and discovered a living cell in 1683.
• Usually a cell has capability to self reproduction.
• Robert Brown discovered cell Nucleus in 1931.
• First Corti saw protoplasm in a cell in 1772.
• Matthias Schleiden and Theodor Schwann give cell theory.

Size of Cell

Cells are of different sizes and shape. Cell are many diversity in it’s shape. A cell can be shaped like a rod, spiral, round, co cylindrical Cells are disc-like, polygonal, columnar, cubic, thread-like or irregular etc. The size of plants cell can be from 15μ to 100μ. Bacterial cells size are between 3μ to 5μ.

Some other facts about cells size

• The smallest cell is Mycoplasma. It’s size about 10mm.
• The largest cell is an egg cell of ostrich. It’s diameter is 15 cm.
• A Bacterial cell length is 3 mm to 5 mm.
• Nerve cell is the longest cell in the human body. It’s size up to 3 feet long.
• The largest cell in the human body is female ovum.
• Human RBC cell diameter is 7mm.
• Boemeria Nivea cell is longest plant cell.
• Esitabureria is longest unicellular cell plants.
  

Different animals have different cell numbers. Some organisms are made up of a few cells, then some organisms body made up by crores cells in the formation of the body. Therefore organisms are of the following types depending on the cells number.
Unicellular Organisms : Organisms whose body is made up of a single cell are called unicellular organisms.
Example – Amoeba, Paramecium etc.

Multicellular Organisms : Organisms whose body consists of more than one cell are called multicellular organisms.
Example – Humans, Elephants etc.

Type of Cell

There are two types are cell which are classified by C.B. Van Neil.
1. Prokaryotic Cell
2. Eukaryotic Cell

1. Prokaryotic Cell : A cell that nucleus membranes around the nucleus and nucleus are not present a well-organized nucleus and absence double membranes In the cell of the organisms, they are called prokaryotes cells. In the prokaryotic cell cell wall is made by peptidoglycan or murein. In the prokaryotic cell 70 ‘s’ type ribosomes are found and DNA & RNA directly contact with cytoplasm. Histone proteins are absence in their chromosome.
Examples – Bacteria, blue-green algae

2. Eukaryotic Cell : A cell which have a conspicuous and advanced nucleus with around nucleus membrane is called Eukaryotic cell.
It’s cell wall is made up of cellulose and pectose. In the prokaryotic cell 80 ‘s’ type ribosomes are found and DNA & RNA directly not contact with cytoplasm. There are Histon proteins is found in Eukaryotic cell. This histon proteins nature is alkaline.
Example – All plants and animals cell, protozoa etc

Difference between Prokaryotic and Eukaryotic Cells

Characteristics	Prokaryotic Cell	Eukaryotic Cell
Size	Its size are less than 1-10μm	This type cell size is grater then prokaryotic cell 5-10μm
Nucleus membrane	Absent	Present
Nucleolus	Absent	Present
Cell Wall	In some organism cell wall absent but in some organism cell wall is present and made up by protein/murine/pseudomurein/glycoprotein or non cellulose polisakarida.	In some organism cell wall is absent but in some it made up by cellulose/kaitin or pectin.
cell membrane	Misosome is found in cell membrane.	Misosome absent
Base Ratio in DNA	In prokaryotic cell base ratio in DNA is A + T/G + C < 1	in Eukaryotic cell base ratio in DNA is A + T/G + C > 1
lysosome	Absent	present
Mitocondria	Absent	present
Ribosomes	only 70s type	both 70s and 80s found
Golgi body	Absent	present
vacuoles	Absent but gas vacuoles found in prokaryotic cell	vacuoles in present in plants cell only
Sexual reproduction	Absent	present
Cell division	A mitosis	Three types of cell division a mitosis, meiosis and mitosis
Plasmid	present	Absent
nitrogen fixation	present	Absent
protoplasm Cyclosis	Absent	present
chromosome	Only Haploid chromosome found	both Haploid and diploid found
Photosynthetic equipment	They are present in some organism and absent in some organism.	They are present in some organism and absent in some organism.
Protein Synthesis	Transcription and translation both are found in cytoplasm.	Transcription in nucleus and translation in cytoplasm.
Flagella	Flagella are made up by Flagellin protein. Which Configuration is 9 + 2.	Flagella are made up by tubulin protein. Which Configuration is 9 + 2.

Difference between Animal and Plant Cells

Characteristics	Plant Cell	Animal Cell
Cell Wall	Cell Wall Present	Cell Wall Absent
Cell Membrane	Present	Present
Nucleus Position	On the side of circumference	In the center
Mitochondria	Very few	In the large amount
Chloroplast	Present	Absent
Vacuoles	Bigger than animal cell	Smaller than plant cell
Lysosome	Absent	Present
Accumulated food	Starch	Glycogen
Centrosome	Absent	Present
Cell Division	Cell Plate Method	Cell Groove Method
Glyoxysomes	Present	Absent
Plasmodesmata	Present	Absent