Cell structure

All living organism are made up of cell. cell is a structural and functinal unit of organism. some
organisms are unicellular while others are multicellular. Each cell is having potentiality to produce a new
individual.This is called totipotency of cell.
On the basis of presence or absence of membrane bound nucleus, organisms are classified into
prokaryotes and eukaryotes. Eukaryotes include plants and animals hence,eukaryotic cells are further
classified into plant cells and animal cells.
Major differences between plant cells and animal cells are presence of cell wall,plastids and vacuole
in plant cells. A typical eukaryotic cell consists of a cell membrane,cytoplasm and nucleus. Cell membrane
also called plasma-membrane is the outermost layer of animal cell and located inner to cell wall in plant
cell.
Eukaryotic cell posseses membrane bound oraganelles like endoplasmic reticulum,golgi apparatus,
lysosomes,and vacuoles.
Endoplasmic reticulum is made up of cisternae.Endoplasmic reticulum having ribosomes on its
outer- surface is called rough endo- plasnic reticulum.It is associated with the synthesis of protein.
Endoplasmic reticulum without ribosomes is known as smooth endoplasmic reticulum. It take part
in the synthesis of lipid. Goigi apparatus is made up of flattened sac like structure.
Lysosomes are surrounded by a single layer wall.They contain enzymes which digest all
macromolecules. In plant cell large vacuole are present which possess a membrane called tonoplast.
As the mitochondria are associated with the generation of ATP they are called power house of cell.
The chloroplast is a double layered structure and possess grana and stroma.
70s type ribosomes are present in prokaryotic cells while 80s type of ribosomes are present in
eukaryotic cells. The shape of cytoplasm and the shape of cell is maintained by cytoskeleton which is made
up of microfilament, microtubules and intermediate filaments.
Eukaryotic cell possesses nucleas, nucler membrane,nucleous and chromatin. Depending on the
position of centromere chromosomes are four types, like Metacentric,sub-metacentric,Acrocentric and
Telocentric.

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