Cellular Components PDF

Cell components and functions Cell structures and functions 100 trillion cells in human body Cells are basic unit of body. They aggregated with supporting extra- cellular matrix to form organs. Cells differ in their functional aspect from tissue to tissue Different substances that m...

Cell components and functions Cell structures and functions 100 trillion cells in human body Cells are basic unit of body. They aggregated with supporting extra- cellular matrix to form organs. Cells differ in their functional aspect from tissue to tissue Different substances that make up the cells: protoplasm Home work: cell components and their function. Water content of cells= 70% or more Important ions inside cells= K+, Mg+, PO4-, SO4-, HCO3- Smaller quantities of Na+, Cl-, Ca+ also found Proteins= structural or functional Lipids: phospholipids, cholesterol are important ones Carbohydrates= part of glycoprotein and for nutrition of the cells Membrane structure of the cells Lipids and proteins Lipid bilayer of phospholipid molecules Impermeable to water soluble substances as ions, glucose, urea Permeable to fat soluble substances, O2, CO2, alcohol Integral and peripheral proteins Channels (pores), carrier proteins, enzymes, receptors for water soluble chemicals (Peptide hormones) Endoplasmic reticulum Ribosomes= granular ER = RNA +Proteins: forms new protein molecules Agranular part= lipid molecules Prominent in liver cells where protein synthesis is high Golgi apparatus Prominent in secretory cells ER vesicles or transport vesicles from ER > Join with golgi Transported substances are processed to form lysosomes, secretory vesicles etc Lysosomes Peroxisomes Provide intracellular digestive Formed by self-replication or from system: smooth ER 1. damages cellular structures Contain oxidases (not hydrolases) 2. food particles ingested by the From H2O2 cells Acts along with catalases found in 3. unwanted stuff like bacteria peroxisomes They oxidize a number of 500 nm in size with a number of substances otherwise poisonous to 5nm sized particles within it cells Containing a number of hydrolytic enzymes Secretory vesicles from ER-golgi system Many times they contain protein proenzymes Granular ER= Proteins formed Smooth ER= lipids esp. phospholipids and cholesterols Golgi apparatus= processes above stuff Secretory vesicles from it: either exocytosis or replenish cellular membrane Mitochondria= powerhouse of the cell Number depends on metabolic status of the cells ATP Also contains DNA for replication of mitochondria Cell cytoskeleton: filament or tubular structures Actin (towards cell membrane) Microtubules Nucleus contains a large amount of DNA which contains genes During mitosis, the chromatin material organized into chromosomes Pores in nuclear membrane are around 9nm, passing up to 44000 MW molecules Nucleolus is accumulation of large amount of RNA & proteins Functional system of the cell: ingestion of the cell= endocytosis 2 types= pinocytosis (minute particles) and phagocytosis (large particles) Pinocytosis is rapid in macrophages (seen under electron microscope) Energy production vs. utilization