Cell and Cell Organelles PDF

CELL AND CELL ORGANELLES Dr. Rasha Eldeeb Associate Professor of Physiology September 3, 2024 1 www.gmu.ac.ae COLLEGE OF PHARMACY  CELL...

CELL AND CELL ORGANELLES Dr. Rasha Eldeeb Associate Professor of Physiology September 3, 2024 1 www.gmu.ac.ae COLLEGE OF PHARMACY  CELL AND CELL ORGANELLES Learning Objectives: Describe the general characteristics of cells Describe the structure of a typical cell Describe the structure of the plasma membrane (Fluid Mosaic Model) Discuss the function of the membrane proteins Describe the structure and function of the different cell organelles.  What Is Physiology? It is the branch of biology that studies the functions and vital processes of living organisms. It explains the physical and chemical factors responsible for life's origin, development, and progression.  Why Do We Study Physiology? To understand the physiologic principle that underlies normal function to cure impairments Distinguish between Process & Function Physiology Integrate both to complete the picture!  What You Should Know is… The Human body is organized from cells to organs The organ systems operate as integrated units The human body needs a constant internal environment to perform its function properly Physiology deals with the mechanisms that maintain a stable internal environment despite the changes in the external environment (Homeostasis) What is the structural and Functional Unit of life? The Cell The Prokaryotic and Eukaryotic Venn Diagram The Cell  The Cell Membrane The cell membrane (plasma membrane) is a thin, elastic, and semipermeable barrier between the cell and its surroundings. Its Lipid bilayer consists of phospholipids and cholesterol, only 2 molecules thick, and continuous over the entire cell surface. Each molecule has : – Head: is the phosphate portion of phospholipids that are charged ( polarized) and soluble in water (hydrophilic). – Tail: is the lipid portion of phospholipids, that is uncharged (non-polarized) and relatively insoluble in water (hydrophobic) The hydrophilic ends are exposed to H2O present outside [extracellular fluid (ECF)] and inside [intracellular fluid (ICF)] the cell, while the hydrophobic ends meet in the water-poor interior of the membrane.  The Cell Membrane Proteins: 55% They do not form a continuous layer as lipids but, they exist as globular units that may be either : – Integral proteins: that extend through the whole thickness of the membrane. – Peripheral proteins: They are attached to the surface of the cell membrane either from inside or from outside i.e. they do not penetrate the whole thickness of the membrane. The functions of cell membrane proteins ▪ Structural proteins (lipoproteins and glycoproteins) ▪ Pumps (Na+/K+ pump) ▪ Receptors (for hormones, chemical transmitters,….) ▪ Carriers (glucose transporters) ▪ Enzymes (adenyl cyclase enzyme) ▪ Ion channels (Na +, K+, and Ca2+ channels) ▪ Tissue typing, and antibody processing (immunity) Carbohydrates: 3%: They are either combined with proteins (glycoproteins) or with lipids (glycolipids). When they cover the whole membrane, they are called glycocalyx.  The Cell Membrane The functions of the Cell Membrane Regulate the passage of substance into and out of cells Detect chemical messengers arriving at the cell surface Link adjacent cells together by membrane junctions Anchor a variety of proteins, including intracellular and extracellular protein filaments involved in the generation and transmission of force, to the cell surface  The Nucleus Usually, it is the largest organelles It is bounded by a nuclear membrane (envelope) with pores It controls the normal cell function Contains the DNA in chromosomes Each cell has a fixed number of chromosomes that carry genes The genes control cell characteristics What is inside the nucleus? It is the largest structure present inside the boundaries of the nucleus It is the dark staining zone in the center of the nucleus It is the place where intensive synthesis of ribosomal RNA takes place Its main components are ribonucleic acid (RNA), deoxyribonucleic acid (DNA) and proteins What is inside the nucleus? The genetic material (DNA) is found which is the hereditary material of the cell DNA is spread out and appears as Chromatin in non-dividing cells DNA is condensed and wrapped around proteins forming as Chromosomes in dividing cells  The Mitochondria It’s the size of a bacterium It has a Double Membranous -outer membrane- smooth - inner membrane- cristae It contains its DNA; mDNA, RNA, and ribosomes. It produces high-energy compound ATP It is the Powerhouse of the cell.  The Endoplasmic Reticulum It is a complex network of transport channels. It is Two types: 1. Smooth- ribosome free - detoxify drugs and pesticides. -absorb, synthesize, and transport fat -break down glycogen to form glucose. 2. Rough - contains ribosomes - manufactures proteins.  The Ribosomes It contains two sub-units It is the site of protein synthesis; therefore, it is considered ad the Protein factory of the cell It is either free-floating or attached to the Endoplasmic Reticulum.  The Golgi Apparatus It is a series of flattened sacs that modifies, packages, stores, and transports materials out of the cell. Works with the ribosomes and Endoplasmic Reticulum.  The Lysosome It is a membrane-bound organelle containing a variety of enzymes. It contains digestive enzymes It helps digest food particles inside or outside the cell. They are called suicide bags  The Cytoskeleton It is the framework of the cell It contains small microfilaments and larger microtubules. They support the cell, giving it its shape and helping with the movement of its organelles.  The Cytoskeleton MICROTUBULES It is a hollow tube present in all cell types except RBCs It is responsible for the intracellular movement of cytoplasmic Organelles It forms Cilia and Flagella MICROFILAMENTS It is attached to the cytoplasmic side of the Plasma Membrane It strengthens the cell surface INTERMEDIATE FILAMENTS It is tough, insoluble protein fiber with strength It resists pulling forces on the cell  The Cellular Extensions Microvilli: Tubular extensions of the plasma membrane which contain actin filaments Stereocilia: Modified Microvilli seen on the cells in the Epididymis Cilia are shorter and more numerous in cells; they move in a single direction across the cell pair Flagella are longer and fewer (usually 1-3) on cells What is the difference between Cytosol and Cytoplasm? Remember https://www.menti.com/alueetusxe5p Learning Resources: 1. Marieb EN. Human Anatomy and Physiology, 9th Edition, Pearson International Edition; 2014. ISBN-13: 978-1-2920-2649-7 2. Guyton, Arthur C. Textbook of medical physiology / Arthur C. Guyton, John E. Hall.—11th ed. 3. Ganong's Review of Medical Physiology/Kim E. Barrett, Susan M. Barman, Scott Boitano and Heddwen L.Brooks,23rd ed. 4. Instructional Web site 5. Lectures PDF on Moodle 6. https://www.clinicalkey.com/#!/content/book/3-s2.0-B9780702031144000026  DISCLAMER The contents of this presentation, can be used only for the purpose of a Lecture, Scientific meeting or Research presentation at Gulf Medical University, Ajman. www.gmu.ac.ae