GOLGI APPARATUS It is a membranous complex of vesicles, vacuoles, and flattened sacs in the cytoplasm of cells which is involved in intracellular secretion and transport. It is found in all eukaryotic cells. It is sometime called as Golgi Body or Golgi Complex.
DISCOVERY Golgi apparatus was discovered by Camillo Golgi in 1898. He developed a method that stained it intensely and made possible the demonstration of its occurrence in a wide variety of cell types. This method is known as Golgi Staining.
Structure and Composition Golgi apparatus is composed of stacks of membrane-bound structures known as Cisternae. A cisterna (plural cisternae) comprises a flattened membrane disk that makes up the Golgi apparatus. Golgi apparatus usually has 6-7 cisternae. A complex network of tubules and vesicles is located at the edges of these cisternae.
Structure and CompositionThe cisternae stack has two faces. Trans-Golgi Cis-Golgi
FUNCTIONS Golgi apparatus is concerned with cell secretion. It involves in the creation of lysosomes. The most important function of this apparatus is to modify the proteins and lipids by adding carbohydrates and converting them into glycoproteins or glycolipids.
CYTOSEKELTON Cytoplasm contains a complex network of filaments and microtubules which form a structural framework known as Cytoskeleton.
Structure and Composition The primary components of the cytoskeleton are microtubules, microfilaments and intermediate filaments.
Structure and Composition Microtubules: Microtubules are long, unbranched, slender tubulin protein structures. One very important function of it is their role in the assembly and disassembly of the spindle structure during mitosis. Intermediate filaments: They have diameter in b/w those of microtubules & microfilaments. They play role in the maintenance of cell shape.
Structure and Composition Microfilaments: They are considerably more slender cylinders made up of actin protein. They involved in internal cell motion.
FUNCTIONS It provides structural support to the cell. It involves in cell motility, cell division and regulation. It plays an important role in intracellular transport. It often protects the cell.
ENDOPLASMIC RETICULUM It is a extensive network of folded membranes that extends from the nuclear envelope to which it is connected throughout the cytoplasm.
Endoplasmic Reticulum Endoplasmic Reticulum is divided into two sub-compartments. • Smooth endoplasmic reticulum • Rough endoplasmic reticulum
SMOOTH ENDOPLASMIC RETICULUM In some cell it is responsible for transmission of impulses (muscle cell, nerve cell). It plays an important role in the transport of materials from one part of the cell to the other.
Structure and Composition It is a branching tube structure which is held by cytoskeleton. In smooth endoplasmic reticulum ribosomes are not attached, therefore its surface is smooth. It contains collection of enzymes.
FUNCTIONS Synthesis of fatty acids and steroid hormones such as estrogens and testosterone. Detoxification in the liver of a wide variety of organic compounds, including barbiturates & ethanol. Metabolize different types of molecules particularly lipids.
LYSOSOME Lysosomes are cytoplasmic organelles. Lysosome founds in almost all eukaryotic cells. Lysosomes have digestive enzymes.
LYSOSOME They are most abundant in those animal cells which exhibit phagocytic activity.
Structure and Composition They are bounded by a single membrane and are simple sacs rich in acid phosphates and several other hydrolytic enzymes. The membrane acts as a protective barrier that protects the rest of the cell from the enzymes that are contained within the lysosome.
FUNCTIONS It is involved in the autophagy (self eating). Any foreign object that gains entry into the cell is immediately engulfed by the lysosome and is completely broken into simple digestible pieces. This process is known as phagocytosis (eating process of a cell).
CENTRIOLE Hollow cylindrical organelles present in animals and many unicellular living organisms. Animal cells, cells of some microorganisms and lower plants contain two centrioles located near the exterior surface of the nucleus. These two centrioles are collectively called as centrosome.
Structure and Composition Centrioles are made up of nine microtubule triplets. These microtubule triplet is made up of tubulin protein. Centrioles are also the part of cytoskeleton.
Structure and Composition The two centrioles are usually placed right angle to each other. They are absent in higher plants.
FUNCTIONS They made spindle fibers during cell division. They play important role in the formation of cilia. They involves in the location of furrowing during cell division.