Question

define cell organelles

Answer 1

A cell organelle is a compartment of a cell that has a specific function of its own.

Answer 2

Organelles are the living bodies inside the cells. These are mainly the characteristics of a eukaryotic cell. These show the division of labor at the cellular level and carry out all the activities inside a cell. The physiology of a cell can be attributed to the collective functions of these organelles. Each organelle has it's specific function(s). The functions of major organelles can be stated briefly as -
 Nucleus - stores the genetic material; controller and director of all cellular functions
Endoplasmic reticulum - structural frame to cell and skeleton of the cell; cell junction formation; secretion; protein synthesis (rough ER); lipid and derivatives are synthesized(smooth ER)
Golgi bodies - modification of synthesized materials (ex. proteins and lipids) ; regulation of molecular traffic inside the cell; secretion (intracellular as well as outside)
Mitochondria - site of aerobic respiration as well as the synthesis of many useful substances 
Lysosomes - hydrolytic digestive enzymes active at acidic pH and help in digestion of unwanted, old, dead substances
Ribosomes - site of protein synthesis
Plastids - store reserve food materials and pigments
Centrosome - involved in cell division 
Cilia and flagella - extend outside the cell and help in motility 
Vacuole - stores excess minerals, water, and excretory substances which are transported inside against the concentration gradient
Cytoplasm - the main arena for all the cellular activities; polyphasic and crysto - colloidal in nature
Cell wall - outermost covering; mechanical support and protection; permeable in nature; variable composition among different groups of organisms
Cell membrane - selectively permeable; composed of mainly lipids and protein.