Monday, April 02, 2012

CELL STRUCTURE AND ORGANISATION

CELL STRUCTURE AND ORGANISATION

The cytoplasm contains organelles and an internal membrane system called the endoplasmic reticulum (ER). It is an organelle of cells in eukaryotic organisms that forms an interconnected network of tubules, vesicles, and cisternae.

Rough ER (RER) transports proteins from the ribosomes to the Golgi apparatus for secretion out of the cell. Rough endoplasmic reticula are involved in the synthesis of proteins and is also a membrane factory for the cell, while smooth endoplasmic reticula is involved in the synthesis of lipids, including oils, phospholipids and steroids, metabolism of carbohydrates, regulation of calcium concentration and detoxification of drugs and poisons.

Ribosomes are involved in protein synthesis. Most are attached to RER but some lie freely in the cytoplasm.

Smooth ER (SER) is involved in producing fats and steroids and in detoxification.

The Golgi apparatus, also known as the Golgi complex or Golgi body, secretes substances made by the ER out of the cell. It also stores and modifies substances for secretion. This organelle found in most eukaryotic cells.

Vesicles transport substances within the cell.

Mitochondria provide energy when food substances are broken down by oxidation during cell respiration. This membrane-enclosed organelle found in most eukaryotic cells.

Chloroplasts are the sites for photosynthesis. They are present only in plant cells.

Centrioles play a part in cell division. They are present only in animal cells.

Vacuoles in animal cells are small, numerous and temporary. They contain food substances and water. Plant cells have a large central vacuole containing cell sap.


sources:
Biology Matters
http://en.wikipedia.org/wiki/


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