L4 - Cells I-2 Lecture Notes PDF

Log into iClicker and join today’s session! LECTURE FOUR CELLS I © Dr. Nicole M. Ventura, PhD. © All slides are property of Dr Ventura. Ins...

Log into iClicker and join today’s session! LECTURE FOUR CELLS I © Dr. Nicole M. Ventura, PhD. © All slides are property of Dr Ventura. Instructor Assistant Professor, Teaching Stream generated course materials are protected by law and may not be copied or distributed in any form or in any School of Kinesiology & Health Sciences medium without explicit permission of Dr Ventura and/or 3rd party (published texts) where applicable. Faculty of Health, York University LEARNING OBJECTIVES Define the primary components of the cell Identify, define and discuss the structure and function of intracellular components (cytoplasm and the organelles found within the cell) Identify, define and discuss the structure and function of the three types of cellular extensions: cilia, flagella and microvilli Discuss the structure and function of the plasma membrane of the cell Define and discuss the various mechanisms by which substances can cross the plasma membrane of the cell: Passive Transport – simple diffusion, facilitated diffusion (carrier-mediated, channel mediated), osmosis Active Transport – primary and secondary Endo- and Exo-cytosis Define and discuss the various fluid compartments of the body. THE CELL: THE BASIC UNIT OF LIFE The Cell = The Smallest Living Unit! Three main components of the cell: 1. Cell (Plasma) Membrane 2. Cytoplasm 3. Nucleus Consists of … cytosol + organelles of the cell (intracellular fluid) the “Brain” of the cell Cells contain their own complete set of instructions (genetic material - DNA) for carrying out their individual activities INSIDE THE CELL: THE CYTOPLASM CYTOSOL: jelly-like fluid that suspends the organelles within the cell 90% water with variety of dissolved ions, amino acids, sugars, lipids Other Parts of the Cell: Cellular extensions (cilia, flagellum, microvilli) Nucleus (nuclear envelope, nucleolus, chromatin) ORGANELLES of the Cytoplasm we are interested in: Mitochondria Smooth Endoplasmic Microtubules Ribosomes Reticulum (SER) Intermedial Filaments Rough Endoplasmic Golgi Apparatus Micro Filaments Reticulum (RER) Peroxisomes Centrosome/Centrioles Lysosomes ORGANELLES OF THE CYTOPLASM MITOCHONDRIA: The powerhouse of the cell! Provides energy Number reflects cell’s energy needs Has a double membrane (important for ATP formation) RIBOSOMES: Site of protein synthesis Free floating in cytosol Membrane-bound – attached to RER ROUGH ENDOPLASMIC RETICULUM Series of membranes/tubes Processes proteins produced by ribosomes Sends proteins to Golgi apparatus ORGANELLES OF THE CYTOPLASM Smooth ER (SER): Looping network of tubes continuous with RER Synthesis of lipids, mobilization of glucose from glycogen Sarcoplasmic reticulum (muscle) – Ca2+ storage GOLGI APPARATUS: The distribution center of the cell! Stacked flat sacs Receive proteins from RER and prepares them for distribution (within cell or outside cell) Receives and distributes via vesicles ORGANELLES OF THE CYTOPLASM LYSOSOMES: recycling center of the cell Membranous sacs containing digestive enzymes Intracellular digestion of toxic substances and waste products Can trigger cell death - Autolysis PEROISOMES: Membranous sacs containing oxidase enzymes Detoxification Breaks down harmful hydrogen peroxide into water and oxygen ORGANELLES OF THE CYTOPLASM MICROFILAMENTS INTERMEDIATE FILAMENTS MICROTUBULES Strengthens cell surface Strongest of the three Near the nucleus/cell center Resist compression of cell Located interiorly in the cell Anchor for organelles Assist in cell movement (ex. Resists pulling forces on the Position organelles and Skeletal muscle) cell moves them in the cell ORGANELLES OF THE CYTOPLASM CENTROSOMES: the “center of the cell” Composed of two centrioles and microtubules Generates microtubules Generates mitotic spindles during cell division THE NUCLEUS The “brain” of the cell Contains genetic material Some cells have none (“anucleate” – mature RBCs) or several (“multi-nucleate” – skeletal muscle) NUCLEAR ENVELOPE: Double membrane separated by fluid-filled space OUTER: continuous with RER and has ribosomes INNER: maintains nucleus NUCLEOLUS: shape and organizes DNA One or two within each nucleus Regulates entry/exit of Form ribosome components (these leave substrates nucleus then assemble fully) THE NUCLEUS CHROMATIN within the NUCLEUS Composed of DNA and histone proteins (proteins that organize DNA) Becomes condensed and active for cell division CELLULAR EXTENSIONS CILIA FLAGELLA MICROVILLI Generated by Generated by Small, finger-like centrioles and made up centrioles and made up projections of many microtubules of mainly microtubules No movement Multiple cellular Longer Increase surface area extensions Propels the cell itself of specialized plasma Shorter using propellar like membranes Move substances along motion Typical in absorbing cell surface – beating Only one in humans: cells (ex. In forward and backward sperm gastrointestinal tract) Located on many human cells THE PLASMA MEMBRANE Lipid bilayer surrounding the body of cells Separates extracellular materials from intracellular ones Is in constant flux → a dynamic fluid structure Selectively permeable TRANSPORTATION ACROSS THE PLASMA MEMBRANE 1. Passive Transport: substances move down a concentration (high to low) gradient without requirement of energy 2. Active Transport: energy-requiring process where substances are moved up their concentration gradient (low to high) PASSIVE TRANSPORT ACROSS THE MEMBRANE SIMPLE FACILITATED DIFFUSION FACILITATED OSMOSIS DIFFUSION CARRIER-MEDIATED DIFFUSION … diffusion of a … of fat-soluble … via protein carrier CHANNEL-MEDIATED solvent such as molecules specific for one chemical; … through a channel water through a directly through binding of substrate protein; mostly ions specific channel the causes transport protein selected on basis of protein (aquaporin) phospholipid to change shape size and charge or through the lipid bilayer bilayer ACTIVE TRANSPORT ACROSS THE MEMBRANE PRIMARY ACTIVE TRANSPORT SECONDARY ACTIVE TRANSPORT … requires energy source (ATP) to … harnesses energy released by move solutes across the one particle going down its membrane AGAINST their electrochemical gradient to drive concentration gradient a different particle up its gradient EX. Na+/K+ pump EX. Na+/Glucose Symporter BULK TRANSFER OF SUBSTANCES FOR CELLS ENDOCYTOSIS: Bulk transport INTO cells Used to bring in molecules like polar substances large molecules EXOCYTOSIS: Bulk transport OUT of cells Cell moves packages of substances from inside the cell to the outside  BODY FLUID COMPARTMENTS INTRACELLULAR = Inside the Cell EXTRACELLULAR = Outside the Cell Fluid that surrounds the cell and, and not in blood Fluid component of blood INTRACELLULAR FLUID = substances contributing to body mass that are found inside the cell EXTRACELLULAR FLUID = substances contributing to body mass that are found outside the cell LET’S RELATE THIS TO A CLINICAL SCENARIO Patient ’X’ has been admitted to the hospital for dehydration after experiencing severe vomiting and diarrhea for the past 48 hours. His blood tests reveal an electrolyte imbalance, with low sodium (hyponatremia) and potassium (hypokalemia) levels. As part of Patient ‘X’s’ treatment, the nursing staff must administer intravenous fluids and monitor the movement of fluids and electrolytes across cell membranes to restore their body’s normal balance QUESTION 1: Patient X’s cells are dehydrated due to the loss of fluids. What process will allow water to move into their cells if the concentration of solutes inside the cells is higher than the concentration outside? A) Simple diffusion B) Osmosis C) Primary Active Transport D) Facilitated diffusion LET’S RELATE THIS TO A CLINICAL SCENARIO Patient ’X’ has been admitted to the hospital for dehydration after experiencing severe vomiting and diarrhea for the past 48 hours. His blood tests reveal an electrolyte imbalance, with low sodium (hyponatremia) and potassium (hypokalemia) levels. As part of Patient ‘X’s’ treatment, the nursing staff must administer intravenous fluids and monitor the movement of fluids and electrolytes across cell membranes to restore their body’s normal balance QUESTION 2: Patient X’s potassium levels are low, and potassium ions need to be transported into their cells. Which transport mechanism allows potassium ions to move against their concentration gradient? A) Diffusion B) Osmosis C) Active Transport D) Facilitated diffusion