Cytology Membranous Organelles PDF

 CYTOLOGY BY Dr/ Mahmoud Abdelghaffar  Cytology It is one of the biological sciences which study the structure, cytochemistry and ultrastructure of the cell. Cytoplasm Nucleus Cell A- Cytoplasm Organelles Inclusions Cytosol ...

 CYTOLOGY BY Dr/ Mahmoud Abdelghaffar  Cytology It is one of the biological sciences which study the structure, cytochemistry and ultrastructure of the cell. Cytoplasm Nucleus Cell A- Cytoplasm Organelles Inclusions Cytosol  Organelles They are constant in the eukaryotic cell & embedded in the cytoplasm. (a) Membranous (b) non membranous  Membranous Non Membranous Organelles Organelles 1) Cell membrane 1) Free ribosome. 2) Mitochondria 2) Cilia & flagella 3) Endoplasmic reticulum 3) Microtubules. 4) Lysosome 4) Filament & fibrils. 5) Golgi Apparatus 5) centriole Membranous Organelles 1- Cell Membrane Plasma membrane Plasmalemma Definition: It is composed of dense layer of cytoplasm surround the cell L.M: It can not be seen only can seen with E.M & 3 theories explain it. Theories of the structure of cell membrane 1. Linear theory 2. Molecular theory 3. Fluid mosaic theory  1- Linear Theory Cell membrane appear as 3 lines; 2 dense and middle light layers (trilaminar structure)  2- Fluid Mosaic theory Globules of protein move freely through the cell membrane. They are floating & changing their position from time to time. Proteins swim in a sea of phospholipid (ice cubes on sea).  Protein 1. Extrinsic (peripheral) are present in one side of the lipid bilayer (the cytoplasmic side). 2. Intrinsic (integral) present between lipid bilayer from side to side.  3- Molecular theory it indicates biochemical structure of the cell membrane. 1- Phospholipids” hydrophilic head, hydrophobic tail. 2-Protein “integral and peripheral” 3-Carbohydrate “glycoprotein and glycolipid. 4-Cholesterol makes phospholipids backed tightly together  Function 1-Protective 2-Regulate transport in and out of cell. 3-Allow selective receptivity and signal transduction by providing receptors that bind signaling molecules. 4- maintain the shape of cells. 5- Provide a stable site for the binding and catalysis of enzymes 2- Mitochondria Definition: It is one of the membranous organelles. they are the power house of the cell which provide the energy a cell needs to move, divide, produce secretory products. L.M: It can be seen using (supra vital dye of Janus) “green color”. E.M: It may be rods, threads or granules. About 2500- 3000 in each cell & increase in cell with high metabolic action.  Bounded with 2 membranes. “Outer smooth membrane, inner folded forming crista which divided mitochondria into incomplete compartments. The inner membrane has mitochondrial granules which have binding site (diformazan granules).  It also contains ribosome like particles. It also contains enzymatic granules. It also contains DNA in close ring (maternal DNA). Function:- 1. Power house of the body. 2. Contain enzyme of crib’s cycle. 3- Endoplasmic Reticulum Definition: It is a system of membranes which is the site of manufacture of proteins and lipids in the cells. There are 2 types (Rough and Smooth ER) Rough Endoplasmic Reticulum (R.E.R.) Definition: It is a membranous organelle. "Rough due to RIBOSOMES attached to the surfaces of the endoplasmic reticulum. L.M: Appear as basophilic substance of the cytoplasm. (RER+ ribosome) in the nerve cell called Nissl’s body.  Acidophilic (E) Basophilic (H) E.M: 3D networks of branching & anastomosing membrane given widen sacs like structure “Cisternae”. It continues with nuclear envelope. Ribosome present on the surface of the sacs gives rough appearance. Function: 1. Synthesis of intracellular protein 2. Play role in glycogen biosynthesis. 3. Its fluid filled channel facilitates diffusion of metabolite through the cytoplasm. Smooth Endoplasmic Reticulum (S.E.R.) Definition: It is membranous network devoid of ribosome. L.M: can not be seen. E.M: The cisternae more tubular Interconnected and communicate with r.E.R. It believed now that s.E.R derived from r.E.R after losing attached ribosome. Function: 1. Biosynthesis of lipids & fatty acid. 2. Biosynthesis of cholesterol & steroid hormones. 3. Synthesis of glycogen. 4. Drug detoxification in the liver cell. 4- Golgi Apparatus Golgi Complex Golgi Network Definition: It is membranous organelles consists of several number of flatten sacs like plate of cups in several location of the cell. These are usually connected to RER as the Golgi apparatus stores and then transports the proteins produced in RER. Because of its functions of storage and transporting proteins, the Golgi apparatus may be creatively thought of as the "Post Office" of the cell. L.M: can not be seen. The shape of the Golgi apparatus varies according to physiological state: Hungary→ small dense body in intestinal cell. Feeding→ increase in size. Aging → became fragmented. EM: Parallel array of smooth surface membrane called flatten saccules or cisternae. These cisternae flatten peripherally “budding” it has two surface (convex – concave): 1- Concave (mature or trans), it associated with secretory vesicles of various stage of condensation & maturation 2- Convex (immature or Cis), it associated with transferred vesicle of RER. Function 1- Concentration of protein from transferred vesicle. 2- Conjugation of protein to polysaccharides “glycoprotein”. 3- Concentration of hydrolytic enzymes. 4- Synthesis of polysaccharides. 5- Play role in exocytosis process. 5- Lysosome Definition: Membranous organelles contain hydrolytic enzyme act on acidic pH medium. Lysosomes are tiny sacs filled with enzymes that enable the cell to utilize its nutrients and are responsible for destroying the cell after it has died. It derived from Golgi complex. E.M → homogenous vesicle bounded with thin membrane filled with hydrolytic enzyme.  How lysosomes are formed. The lysosome are the freshly formed secretory vesicle contain hydrolytic enzyme “primary lysosome” It comes from RER as transfer vesicle contains enzyme. When they grow up in the saccules of the Golgi they bud off from the mature face of the Golgi as secretory vesicle. Secondary lysosome, when the primary lysosome phagocytosis any undesirable vesicle in the cytoplasm. If fuse with phagocytic vesicle “phagosome” when enzyme digest vesicle → residual body. If fuse with old cytoplasmic content “autophagic vacuole”. If fuse with fluid (pinocytotic vesicle). Function:- 1- Intracellular metabolism of carbohydrate. 2- phagocytosis, pinocytosis, and autophagy. 3- Breakdown of excessive secretory granules. Thank You