Cell Biology, Part 1 2023.pdf

CELL BIOLOGY I PA517: Physiology and Pathophysiology I Cell Biology Prt. 1  INSTRUCTIONAL OBJECTIVES 1.1. Compare and contrast eukaryotes and prokaryotes. 1.2. Summarize the major cellular functions of cells. 1.3. Discuss the structure and function of eukaryo...

CELL BIOLOGY I PA517: Physiology and Pathophysiology I Cell Biology Prt. 1  INSTRUCTIONAL OBJECTIVES 1.1. Compare and contrast eukaryotes and prokaryotes. 1.2. Summarize the major cellular functions of cells. 1.3. Discuss the structure and function of eukaryotic organelles and cell structures. 1.3.1 Nucleus 1.3.2 Cytoplasm 1.3.3 Ribosomes 1.3.4 Endoplasmic Reticulum 1.3.5 Golgi Complex 1.3.6 Lysosomes, peroxisomes 1.3.7 Mitochondria 1.3.8 Cytoskeleton 1.3.9 Plasma Membrane 1.3.10 Proteins, Lipids and Carbohydrates  ALL BODY FUNCTIONS DEPEND ON THE INTEGRITY OF CELLS Cells work together to behave as a multicellular “social” organism. LIVING CELLS ARE DIVIDED INTO TWO MAJOR CLASSES EUKARYOTES VS PROKARYOTES  CELLS ARE DEFINED BY THEIR SPECIALIZED FUNCTIONS Specialization occurs through the process of differentiation so that some cells eventually perform one kind of function and other cells perform other functions.  THERE ARE EIGHT CHIEF CELLULAR FUNCTIONS Movement (muscle cells) Conductivity (nerve cells) Metabolic Absorption (intestinal epithelial cells) Secretion (hormones from endocrine glands) Excretion (waste products from lysosomes) Respiration (oxygen used to convert nutrients into ATP) Reproduction (skin cells are replaced continuously) Communication (cells in different tissues communicate to control processes-ex digestion) STRUCTURE AND FUNCTION OF CELLULAR COMPARTMENTS  CELL COMPONENTS Typical eukaryotic cells consist of 1.Plasma membrane 2. Cytoplasm 3. Intracellular organelles The Central Dogma of Molecular Biology *These functions occur in different locations within the cell!  NUCLEUS Centrally located organelle Surrounded by cytoplasm Largest membrane-bound organelle  NUCLEUS Composed of a double membrane, the nuclear envelope Fluid filled interior, nucleoplasm Contains Nucleolus Cellular DNA Histones THE NUCLEUS FUNCTIONS TO MEDIATE CELL DIVISION THE NUCLEUS ALSO CONTROLS HOW GENETIC INFORMATION IS USED FOR CELLULAR FUNCTIONS DNA Transcription into mRNA occurs in the Nucleus https://www.youtube.com/watch?time_continue=117&v=gGeC0ntvxR8 Transcribed mRNA Leaves the Nucleus Through Nuclear Pores CYTOPLASM IS THE AQUEOUS SOLUTION THAT FILLS THE SPACE BETWEEN THE NUCLEAR ENVELOPE AND THE PLASMA MEMBRANE  Contains thousands of enzymes (including those that will interact with mRNA)  Newly synthesized proteins present here  RIBOSOMES ARE ORGANELLES MADE OF RNA AND PROTEIN RNA-protein complex (nucleoproteins) that are synthesized in the nucleolus Function in protein synthesis Recognizes a “signal recognition sequence (SRP) on mRNA” The Activities of the Central Dogma Occur in Different Cellular Compartments RIBOSOMES ARE FOUND FLOATING FREE IN THE CYTOPLASM OR ATTACHED TO THE ENDOPLASMIC RETICULUM The Central Dogma of Molecular Biology  ENDOPLASMIC RETICULUM endo=within; plasma=cytoplasm; reticulum=network Synthesizes and transports protein and lipid components of the cell’s organelles Network of tubular channels that extend throughout the cytoplasm.  ENDOPLASMIC RETICULUM Rough ER contain ribosomes Smooth ER does not ER communicates with the Golgi and other membrane bound organelles (lysosomes and peroxisomes)  GOLGI COMPLEX/APPARATUS Network of flattened, smooth membranes and vesicles frequently located near the nucleus of the cell Proteins from the ER are processed and packaged into small membrane-bound sacs or vesicles called secretory vesicles  GOLGI COMPLEX Secretory vesicles break off from the Golgi and migrate to intracellular and extracellular destinations SYNTHESIS OF A SECRETED PROTEIN 5. Proteins leave Golgi in secretory vesicles that fuse with the plasma membrane 4. Protein travels to the Golgi via vesicle and is modified 3. Protein is transcribed by ribosomes 2. mRNA leaves nucleus to a ribosome on the rER 1. Protein “instructions” are transcribed in the nucleus Other Cytoplasmic Organelles  LYSOSOMES Lyso=dissolution; soma=body Saclike structures that originate from the Golgi Contain digestive enzymes(enzyme= specialized protein)  LYSOSOMES DIGEST WASTE PRODUCTS Function as the intracellular digestive system; if things break in the cell, lysosomes encase a broken component and digest/break down the component in the lysosome membrane) Cellular constituents Normal cellular nutrients Intracellular debris Lysosomal Storage Diseases Result from Lack of One or More Lysosomal Enzymes https://emedicine.medscape. com/article/944157-overview  PEROXISOMES Membrane-bound organelles that contain several oxidative enzymes (catalase and urate oxidase) Detoxify compounds and fatty acids(*and alcohol) Larger than lysosomes  PEROXISOMES Major sites of oxygen utilization Perform reactions that produce and consume hydrogen peroxide (H2O2)  PEROXISOMES H2O2 is a powerful oxidant, potentially destructive if it accumulates or escapes from peroxisomes Catalase uses H2O2 to oxidize phenols, formaldehyde and alcohol by the peroxidative reaction Don’t memorize this  MITOCHONDRIA mito=thread; chondros=granule Contain their own DNA Appear as sphere that are bound by a double membrane  MITOCHONDRIA Outer membrane is smooth and surrounds the mitochondrion Inner membrane is convoluted in the matrix to form partitions call cristae; twists inside membrane create extra surface area to allow for electron transport chain (to create ATP)  CYTOSOL Gelatinous, semiliquid portion of the cytoplasm Functions: site of enzymatic biochemical reactions, protein synthesis, and storage of carbohydrates, fat, and secretory vesicles  CYTOSKELETON Specialized internal structures that provide “bones and muscles” of the cell Maintains cell’s shape and internal organization and permits movement of external structures (cilia, microvilli, flagella) Involved in mechanotransduction (cells convert mechanical stimulus into electrochemical signals)  CYTOSKELETON Internal skeleton is composed of a network of protein filaments Microtubules are small, hollow, cylindrical, unbranched tubules made of protein... facilitate vesicle transport Add strength to the cell’s structure; move organelles MICROTUBULES FACILITATE VESICLE TRANSPORT https://www.youtube.com/watch?time_continue=2&v=y-uuk4Pr2i8 Components of the Plasma Membrane  FUNCTIONS OF PLASMA MEMBRANES Enclose cells and intracellular organelles Allow or exclude molecules through selective transport systems Influence metabolic pathways MEMBRANE FUNCTIONS WITHIN THE CELL POLARIZED MEMBRANES CREATE DIRECTIONALITY IN CELLS Cell membranes are not the same on all sides Polarized domains facilitate directional transport. Cell polarity maintains normal cell and tissue structure Organelles and cytoskeleton are arranged directionally to enable intestinal cell secretion and absorption.  LIPIDS: A MAJOR COMPONENT OF THE PLASMA MEMBRANE Lipids are polar(charged) Membrane spontaneously One part is hydrophobic organizes itself into a bilayer in One part is hydrophilic the presence of water  PROTEINS A protein is made from a chain of amino acids (polypeptide) The sequence of amino acids is known as primary structure Proteins fold into secondary, tertiary, and quaternary structure specific to their function  PROTEINS HAVE MULTIPLE FUNCTIONS IN THE CELL Structural components Enzymes Receptors  PROTEINS FUNCTION IN AND AROUND MEMBRANES Integral- embedded in the bilayer and linked to a phospholipid or fatty acid chain Peripheral- reside at one surface of the bilayer and bound to an integral protein Transmembrane-extend across the bilayer  SOME PROTEINS ARE PROTEASES Proteases are enzymes that cause the breakdown of proteins Zymogen is an inactive protease that becomes a protease after being avtivated  PROTEASES ARE INVOLVED IN THE REGULATION OF ESSENTIAL PROCESSES IN PROTEOLYTIC CASCADES  PHASES OF PROTEOLYTIC CASCADES Initiation-caused by an external stimulus Propagation-initiator converts a downstream propagator Executioner-propagator activates an executer  DISEASES CAN BE RELATED PROTEOLYTIC CASCADES Cell death Blood coagulation Degrading membrane enzymes/matrix metalloproteinase cascade Complement cascade  CARBOHYDRATE COMPONENTS OF THE MEMBRANE Oligosaccharides are connected to membrane proteins (glycoproteins) and lipids (glycolipids)  CELL RECEPTORS ARE MADE OF PROTEINS On the plasma membrane, in the cytoplasm, or in the nucleus Recognize and bind specific smaller molecules (ligands)  CELL RECEPTORS CAN BE LINKED TO CHANNELS THAT TRAVERSE THE PLASMA MEMBRANE Channel-linked Non-channel- receptor linked receptor INSULIN-LIKE GROWTH FACTOR ACTIVATES SIGNAL TRANSDUCTION Receptor binds ligand Signal transduction to nucleus LET’S REVIEW WITH KAHOOT! https://kahoot.it/  ADDITIONAL RESOURCES Cell Structure and Function From DNA to protein: How Proteins are Made