Cellular Transport, Membrane, Metabolism & Tissue Types Lecture Notes (PDF)
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Uploaded by SweetRhyme
Stanbridge University
2023
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Summary
These lecture notes cover cellular transport, membrane structure, and function, along with topics like diffusion, osmosis, mitosis, protein synthesis, and cell junctions. The information is presented in an organized way with diagrams and includes references, likely for a biology or physiology course at the undergraduate level.
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Cellular Transport and The Cell Membrane Fox: Chapter 6 © Stanbridge University 2023 Lecture Objectives Cellular Transport: Name the functions of the membrane proteins Be able to discuss the funct...
Cellular Transport and The Cell Membrane Fox: Chapter 6 © Stanbridge University 2023 Lecture Objectives Cellular Transport: Name the functions of the membrane proteins Be able to discuss the function of the cellular membrane and various types of transport across or through it Understand and explain various types of diffusion, osmosis, and active transport Explain membrane potential Cellular Division: Explain and draw the cell cycle, especially mitosis Making of Proteins: Understand Transcription Understand Translation © Stanbridge University 2023 Membrane proteins involved with transport across the membrane Transport Passive transport: protein (left) that provides a hydrophilic (loves water) channel that is selective for a particular solute Active transport: proteins (right) that use ATP to actively pump substances across the membrane Marieb, 2019 © Stanbridge University 2023 Membrane Proteins Involved in Signal Transduction Receptors for signal transduction Protein with a binding site that fits the shape of a specific chemical messenger, such as a hormone When bound, the chemical messenger may cause a change in shape that Marieb, 2019 initiates a chain of chemical reactions in the cell © Stanbridge University 2023 Membrane Proteins Involved in catalyzing reactions Enzymatic activity Protein may be an enzyme with its active site exposed to substances in the adjacent solution Several enzymes may catalyze sequential steps of a metabolic pathway Marieb, 2019 © Stanbridge University 2023 Membrane Proteins Involved with Cell. Recognition Cell-cell recognition Glycoproteins that serve as identification tags that are specifically recognized by other cells Marieb, 2019 © Stanbridge University 2023 Membrane Proteins Anchor the Inside and Outside of the Cell Attachment to the cytoskeleton and extracellular matrix (ECM) Elements of the cytoskeleton and extracellular matrix anchor to membrane proteins and help maintain cell shape and fix the location of membrane proteins Others play a role in cell movement or bind adjacent cells together Marieb, 2019 © Stanbridge University 2023 Membrane proteins connecting cells Marieb, 2019 Intercellular joining Proteins of adjacent cells may be hooked together Cell adhesion molecules or CAMs of provide temporary binding sites that guide cell migration and other cell-to- cell interactions CAMs Nutrient transfer and structural support CAM = Cell Adhesion Molecules © Stanbridge University 2023 Cell Junctions: Tight Junctions Series of fusion of integral proteins from different cells Impermeable junction Some are “leaky” Marieb, 2019 © Stanbridge University 2023 Cell Junctions: Desmosomes Thin protein filaments connect cells at various points Distribute tension of pulling, along all of the cells that are connected Important in cells of the skin and heart Marieb, 2019 © Stanbridge University 2023 Cell Junctions: Gap Junctions Cells are connected by cylindrical proteins that facilitate communication Types of membranes involved determine what is passible between the cells Found in most electrically excitable tissue Marieb, 2019 © Stanbridge University 2023 Membrane Transport Plasma membranes are selectively permeable Some molecules pass through easily; some do not Two ways substances cross membrane 1. Passive processes 2. Active processes © Stanbridge University 2023 Types of Membrane Transport 1. Passive processes (or passive transport) No cellular energy (ATP) required Substance moves down its concentration gradient 2. Active processes (or active transport) Energy (ATP) required Occurs only in living cell membranes © Stanbridge University 2023 Concentration Gradient The difference in the amount of a solute or substance on one side of a barrier compared to the amount on the other side © Stanbridge University 2023 Types of Passive Transport Diffusion makes a uniform mixture over time (in a closed container) Simple diffusion Osmosis Facilitated diffusion © Stanbridge University 2023 Passive Processes Diffusion: particles move from an area of high concentration to an area of low concentration 1. Simple diffusion- (e.g. H20, O2, CO2 can pass directly through the membrane) Non-polar (hydrophobic) and lipid soluble substances (does not mix with water and fat) © Stanbridge University 2023 Passive Processes (cont.) 2. Facilitated diffusion Marieb, 2019 Carrier-mediated Binding sites allowing small amount of solutes to pass Cavity not open simultaneously to both environments Channel-mediated Allow many solutes to pass through membrane at one time © Stanbridge University 2023 Terms used in diffusion Osmolality: number of particles in solvent Osmolarity: number of particles in solution © Stanbridge University 2023 Diffusion where a membrane is permeable to solutes and water Marieb, 2019 © Stanbridge University 2023 Passive Processes (cont.) Marieb, 2019 3. Osmosis H2 0 moves into an area of lower osmotic concentration (less H20) in order to dilute a substance Basically simple diffusion © Stanbridge University 2023 Diffusion where a membrane is permeable only to water Marieb, 2019 © Stanbridge University 2023 Importance of Osmosis Osmosis can cause cells to swell or shrink Changes in cell volume can disrupt cell function, especially in neurons © Stanbridge University 2023 Osmosis and Tonicity Penetrating solutes Able to diffuse through cell membrane Solutes "pull" water molecules with them Non-penetrating solutes Cannot cross the cell membrane Osmosis of water must occur for the solutions to reach equilibrium © Stanbridge University 2023 Tonicity Tonicity: (amount of solute in a given solvent amount) Ability of a solution to change or alter the shape of a cell by changing the cell’s internal water volume © Stanbridge University 2023 Isotonic Solution Marieb, 2019 Isotonic solution: Contain the same or equal concentrations of solutes that cannot cross the plasma membrane, as those found in a cell Cells retain normal size and shape (water moves in and out) © Stanbridge University 2023 Hypertonic Solution Marieb, 2019 Hypertonic solution: Contain a greater amount of solutes that cannot cross the plasma membrane, than the amount inside of the cell Cells in this environment shrivel with water loss © Stanbridge University 2023 Hypotonic Solution Marieb, 2019 Hypotonic solution: Contain a smaller amount of solutes that cannot cross the plasma membrane, than the amount inside of the cell Cells in this environment enlarge and may burst with influx of water © Stanbridge University 2023 Summary of the types of passive transport across the plasma membrane Marieb, 2019 1 2a 2b 3 © Stanbridge University 2023 Membrane Transport: Active Processes Two types of active processes 1. Active transport 2. Vesicular transport Both require ATP to move solutes across a plasma membrane because 1. Solute too large for channels 2. Solute not lipid soluble 3. Solute not able to move down concentration gradient (i.e. against the law of diffusion) © Stanbridge University 2023 Active Transport Requires a carrier protein in the membrane Bind specifically and reversibly with substance Moves solutes against concentration gradient Requires energy (ATPs) © Stanbridge University 2023 Active Transport: Two Types 1. Primary active transport Requires energy directly from splitting off phosphates from ATP 2. Secondary active transport Requires energy indirectly from ionic gradients created by primary active transport © Stanbridge University 2023 Ions (review) Atom or molecule with a positive or negative electrical charge Cations Na+ and K+ are positively charged Anions Ex. Cl- are negatively charged Too big to leave through any channel/pump Stay put and give the cell a negative charge inside © Stanbridge University 2023 Sodium-Potassium Pump Na+ and K+ channels allow slow leakage down concentration gradients Na+-K+ pump works as antiporter Pumps against Na+ and K+ gradients to maintain Located in all plasma membranes Pumps 3 Na+ out of the cell, while pumping 2 K+ inside of the cell → High intracellular K+ concentration High extracellular Na+ concentration © Stanbridge University 2023 Marieb, 2019 3 cytoplasmic Na+ bind to pump Na+ binding promotes Pump binds ATP; releases to K+ hydrolysis of ATP and energy the inside, and cycle repeats released, phosphorylates the pump K+ binding releases phosphate and pump Phosphorylation causes resumes original 2 extracellular K+ pump to change shape, conformation © Stanbridge University 2023 bind to pump expelling Na+ to the outside Secondary active transport is driven by the concentration gradient created by primary active transport. Marieb, 2019 Extracellular fluid Glucose Na+-glucose Na+-glucose symport transporter symport releases glucose transporter into the cytoplasm loads glucose from extracellular Na+-K+ fluid pump Cytoplasm 1 Primary active transport 2 Secondary active transport The ATP-driven Na+-K+ pump As Na+ diffuses back across the membrane stores energy by creating a through a membrane cotransporter protein, it steep concentration gradient for drives glucose against its concentration gradient Na+ entry into the cell. into the cell. © Stanbridge University 2023 2. Secondary Active Transport Vesicular Transport- moving particles in and out of the cell by way of transport vesicles (“pinched off” sections of membrane); requires energy (ATP) Endocytosis: bringing “in” Phagocytosis, pinocytosis, receptor- mediated endocytosis Exocytosis: moving “out” © Stanbridge University 2023 Endocytosis Phagocytosis: cell engulfing a large or solid material Pinocytosis: cell gulping extracellular fluid that contains solutes (non specific, since no receptors) Receptor mediated endocytosis: receptors are specific to certain substances, once bound, brought into the cell through folding of the membrane (like the other types) © Stanbridge University 2023 Endocytosis Marieb, 2019 © Stanbridge University 2023 Exocytosis Usually stimulated by something being bound to a cell surface Examples of products being Marieb, 2019 released: Hormones Neurotrasmitters Waste Mucus © Stanbridge University 2023 Cell Growth and Reproduction Fox: Chapter 2 © Stanbridge University 2023 DNA Large bundles of DNA are arranged in structures called chromosomes Humans have 46 chromosomes (23 pairs) © Stanbridge University 2023 The cell cycle. Marieb, 2019 G1 checkpoint (restriction point) S Growth and DNA synthesis G2 Growth and final G1 preparations for Growth M division G2 checkpoint © Stanbridge University 2023 Interphase (not part of mitosis) Period from cell formation to cell division G = gap S = synthesis G0 = No activity G1 = Makes organelles and proteins (minutes to hours) S1 = DNA replication (hours) G2 = Preparing for mitosis (hours) © Stanbridge University 2023 Interphase Marieb, 2019 © Stanbridge University 2023 Mitotic Phase: Prophase Four Mitosis phases 1. Prophase: DNA condenses into copied pairs of chromosomes Nuclear membrane dissolves © Stanbridge University 2023 Early Prophase Marieb, 2019 © Stanbridge University 2023 Late Prophase Marieb, 2019 © Stanbridge University 2023 Mitotic Phase: Metaphase 2. Metaphase: (meet in middle) Chromosomes line up in the center of the cell (centromere), attached to microtubules (or spindle fibers), extend out from the centrioles © Stanbridge University 2023 Metaphase Marieb, 2019 © Stanbridge University 2023 Mitotic Phase: Anaphase 3. Anaphase: (apart) Microtubules pull the chromosome copies to either side of the cell © Stanbridge University 2023 Anaphase Marieb, 2019 © Stanbridge University 2023 Mitotic Phase: Telophase 4. Telophase: Nuclear envelope reforms around each new set of chromosomes (genetic material has been divided) “Cytokinesis” refers to the moving apart of the two daughter cells (starts in anaphase and ends after mitosis) © Stanbridge University 2023 Telophase and Cytokinesis Marieb, 2019 © Stanbridge University 2023 DNA (deoxyribonucleic acid) and RNA (ribonucleic acid) DNA bases RNA bases 1. Adenine 1. Adenine 2. Thymine 2. Uracil 3. Cytosine 3. Cytosine 4. Guanine 4. Guanine © Stanbridge University 2023 The Process of Protein Synthesis 1. Transcription (occurs in nucleus) Copy of a DNA sequence (a gene) is transcribed inside the nucleus, called messenger RNA (mRNA). mRNA then travels outside the nucleus into the cytoplasm © Stanbridge University 2023 DNA and Protein Synthesis 2. Translation (occurs in cytoplasm) Ribosome subunits attach to the mRNA and “translate” the sequence of nucleotides Every 3 bases of the mRNA nucleotide corresponds to a specific Marieb, 2019 amino acid or is an instructional code Transfer RNA (tRNA) bring the amino acid to match the codon © Stanbridge University 2023 Transcription and Translation Marieb, 2019 © Stanbridge University 2023 Focus on Translation Marieb, 2019 © Stanbridge University 2023 Cellular Metabolism Marieb, Chapter 24 © Stanbridge University 2023 Metabolism “Metabolism is a sum of all biochemical reactions in the body” Anabolism: Reactions that build larger molecules or structures from smaller ones Ex. amino acids put together to make a protein Catabolism: Processes that break down complex structures into simpler structures Ex. a protein broken down into amino acids © Stanbridge University 2023 Major Stages of Energy Processing 1. GI tract: digestion nutrients are transported in blood to cells in tissue 2. In tissues: anabolic or catabolic in cell cytoplasm, (ex. glycolysis) 3. In mitochondria: mostly catabolic and requires oxygen, producing water and CO2 and making ATP (Kreb’s cycle and oxidative phosphorylation) © Stanbridge University 2023 Cellular Respiration Catabolic reactions where food is broken down, some energy used to make ATP (glycolysis, Kreb’s cycle, oxidative phosphorylation) Body can store energy (ex. glycogen and fats) for production of ATP later ATP fuels energy releasing catabolic reactions to cellular work (ATP reactions are coupled) © Stanbridge University 2023 Marieb, 2019 © Stanbridge University 2023 Cellular Respiration Marieb, 2019 © Stanbridge University 2023 Glycolysis Marieb, 2019 © Stanbridge University 2023 Kreb’s Cycle Marieb, 2019 © Stanbridge University 2023 Oxidative Phosphorylation Along the Electron Transport Chain Marieb, 2019 Marieb, 2019 © Stanbridge University 2023 Electron Transport Chain Marieb, 2019 Marieb, 2019 © Stanbridge University 2023 ATP synthase Marieb, 2019 © Stanbridge University 2023 Total ATP yield from one molecule of glucose Marieb, 2019 © Stanbridge University 2023 Tissues and Tissue Types Chapter 1 © Stanbridge University 2023 Objectives Describe epithelial tissue, including its function, and name some examples Describe connective tissue, all of the types, including their function, and list examples of each Describe nervous tissue Describe muscular tissue and provide examples © Stanbridge University 2023 4 Basic Tissue Types Epithelial Connective Muscular Nervous © Stanbridge University 2023 © Stanbridge University 2023 Marieb, 2019 Epithelial Tissue Naming: First Name=Number of Layers First name: # layers Simple: One layer Stratified: Two or more layers Marieb, 2019 © Stanbridge University 2023 Epithelial Tissue Naming: Second Name= Cell Shape Second name: cell shape All have 6 irregular sides Squamous: more flattened Cuboidal: about the same size all dimensions Columnar: more tall i.e. Simple squamous Marieb, 2019 epithelium, stratified squamous © Stanbridge University 2023 Epithelial Tissue Structure All epithelial tissue has two surfaces Apical surface: not attached to other tissue; faces outside of body or inside of body organ or cavity Basal surface: attached to underlying tissue (usually connective tissue) © Stanbridge University 2023 Marieb, 2019 Simple Epithelia Absorption, secretion, and filtration Not very protective © Stanbridge University 2023 Simple Squamous Epithelium: Two examples Endothelium: (inner) lymphatic vessels and hollow organs of cardiovascular system (blood vessels and heart) Mesothelium: (middle) serous membranes, membranes lining ventral cavity and its organs Marieb, 2019 © Stanbridge University 2023 Simple Cuboidal Epithelium Function: secretion and absorption Examples: kidney tubules; ducts and secretory portions of small glands; ovary surface Marieb, 2019 © Stanbridge University 2023 Simple Columnar Epithelium Function: absorption; secretion of mucus, enzymes, and other substances Examples: ciliated: moves mucus nonciliated: lines most of the GI tract and some parts of the uterus Marieb, 2019 © Stanbridge University 2023 Pseudostratified Columnar Epithelium Function: secrete substances, especially mucus and propelling mucus with cilia Location: ciliated: trachea and most of respiratory tract nonciliated: ducts that carry sperm in males Marieb, 2019 © Stanbridge University 2023 Stratified Squamous Epithelium Function: protects underlying tissues in areas where it could be rubbed Examples: nonkeratinized : linings of esophagus, mouth (moist) Keratinized: epidermis of skin (dry) Marieb, 2019 © Stanbridge University 2023 Transitional Epithelium Function: stretches Examples: ureters, bladder, and part of the urethra Marieb, 2019 © Stanbridge University 2023 Glands and Glandular Epithelium Gland: one or more cells that make and secrete a product, may be unicellular or multicellular, and endocrine or exocrine © Stanbridge University 2023 Glands and Glandular Epithelium Unicellular exocrine glands between epithelial sheets Multicellular exocrine glands form by invagination of epithelial sheets into connective tissue Most have ducts (tubelike connections to epithelial sheets) © Stanbridge University 2023 Glands and Glandular Epithelium Exocrine glands can release their chemicals by bursting or by exocytosis Marieb, 2019 © Stanbridge University 2023 Glands and Glandular Epithelium Endocrine glands: Do not have ducts Secrete into extracellular space → enter blood or lymphatic fluid Produce hormones © Stanbridge University 2023 Connective Tissue: Types and Categories Proper (includes fat and fibrous tissue of ligaments) Cartilage Bone Blood © Stanbridge University 2023 Connective Tissue Functions Binding and supporting Protecting Insulating Storing and reserving fuel Transport of substances Overall connective tissue houses: macrophages, white blood cells (WBC’s), mast cells, and fat cells © Stanbridge University 2023 Connective Tissue Distinct Features Vary in vascularity from avascular to many blood vessels Mainly composed of nonliving extracellular matrix between the living tissue Can withstand more than other tissue types Most diverse of the 4 main tissue types © Stanbridge University 2023 Components of Connective Tissue 1. Ground substance (extracellular matrix) 2. Fibers (extracellular matrix) 3. Cells © Stanbridge University 2023 1. Ground Substance Mostly fluid and acts a diffusion area between cells and blood vessels Can be fluid or more viscous Made up of fluid (interstitial tissue), cell adhesion proteins, and proteoglycans; contains fibers © Stanbridge University 2023 2. Connective Tissue Fibers Collagen: cross-linked fibrils providing very good tensile strength (made of fibrous proteins) Elastin: contains the protein elastin allowing for stretch and recoil ex. skin, lungs, b.v. walls (made of fibrous proteins) Reticular: continuous with collagen fibers and branch extensively to support organ tissue and small b.v.; ex. where connective tissue contacts other tissue types (short, fine fibers) © Stanbridge University 2023 3. Connective Tissue Cells Each major class of connective tissue has a resident cell type that exists in immature (-blast) and mature (-cyte) forms Blast cells: immature cells; secrete ground substance and fibers -Cyte cells: Less active, more mature cells which can revert back as needed to repair and regenerate in times of injury Ex. connective tissue proper: fibroblast → fibrocyte Blood is an exception: Immature blood forming cell: hematopoietic stem cell Not located in its tissue (blood) Does not secrete ground substance (plasma) © Stanbridge University 2023 Schematic of Connective Tissue Types Marieb, 2019 © Stanbridge University 2023 Marieb, 2019 Connective Tissue Proper: Loose Connective Tissue- Areolar Surrounds and pads organs Key role in inflammation Holds and moves tissue fluid Location: under epithelia, surrounds capillaries, part of lamina in mucous membranes © Stanbridge University 2023 Marieb, 2019 Connective Tissue Proper: Loose Connective Tissue- Adipose Reserve fuel Insulation Support and protect organs Ex. under skin in subcutaneous layer around kidneys and eyeballs; abdomen; breasts © Stanbridge University 2023 Marieb, 2019 Connective Tissue Proper: Loose Connective Tissue- Reticular Supports other cell types Ex. lymphoid organs (lymph nodes, bone marrow, and spleen) Marieb, 2019 © Stanbridge University 2023 Connective Tissue Proper: Dense Connective Tissue- Dense Regular Attaches muscles to bones or other muscles, bones to bones, good tensile strength Ex. tendons, ligaments, aponeuroses © Stanbridge University 2023 Marieb, 2019 Connective Tissue Proper: Dense Connective Tissue- Dense Irregular Structural strength in many directions Ex. fibrous capsules of organs and joints; dermis; submucosa of GI tract © Stanbridge University 2023 Marieb, 2019 Connective Tissue Proper: Dense Connective Tissue- Elastic Allows tissue recoil after stretch Marieb, 2019 Maintains pulsatile flow of blood in arteries Aids in passive recoil of Lungs after inspiration Ex. walls of large arteries, some ligaments in vertebral column, walls of bronchial tubes © Stanbridge University 2023 Connective Tissue: Cartilage- Hyaline Cushion, support, reinforce Resists compressive stress Ex. most of embryonic skeleton; Covers ends of longs bones in joints; forms costal cartilage of ribs, cartilage of nose, trachea, and larynx © Stanbridge University 2023 Marieb, 2019 Connective Tissue: Cartilage- Elastic More elastic fibers than in hyaline Maintain shape of structure with flexibility Ex. supports external ear; epiglottis © Stanbridge University 2023 Marieb, 2019 Connective Tissue: Cartilage- Fibrocartilage Absorb compressive shock Ex. intervertebral discs, pubic symphysis, menisci of knee joint © Stanbridge University 2023 Marieb, 2019 Connective Tissue: Bone Supports and protects Levers for muscles Stores calcium, other minerals, fat Marrow inside is where blood cells form Well vascularized © Stanbridge University 2023 Marieb, 2019 Connective Tissue: Blood Red and white blood cells and platelets in a fluid matrix Transport respiratory gases, nutrients, wastes and other substances Ex. inside blood vessels © Stanbridge University 2023 Marieb, 2019 Connective Tissue: Blood Different than other connective tissue types: Does not connect and provide structural support Has a different developmental pathway Made up of non-living blood plasma that surrounds the blood cells Fibers of this tissue are protein molecules that form more of a structure during blood clot formation © Stanbridge University 2023 Muscular Tissue Very cellular, well vascularized Perform most body movement Types: skeletal, cardiac, smooth © Stanbridge University 2023 Skeletal Muscle Tissue Muscle cells= muscle fibers Multinucleated cells, striations Voluntary movement and control Ex. in skeletal muscles, usually attached to bones, sometimes skin © Stanbridge University 2023 Marieb, 2019 Cardiac Muscle Tissue Contractions propel blood through blood vessel to all parts of the body Striated Involuntary control Uninucleated cells usually Branching cells with intercolated discs between Ex. only in walls of heart Marieb, 2019 © Stanbridge University 2023 Smooth Muscle Tissue No striations in cells One nucleus Involuntary control Propels substances through Internal passageways Ex. walls of hollow organs (not heart), GI and urinary, uterus, blood vessels © Stanbridge University 2023 Marieb, 2019 Nervous Tissue Cells generate and conduct nerve impulses Supporting cells support and protect neurons Cells can be long Ex. brain, spinal cord, nerves Marieb, 2019 © Stanbridge University 2023 Assess your learning © Stanbridge University 2023
