Cell Structure and Function PDF

Chapter 3 Cell Structure and Function PowerPoint® Lecture Slides prepared by Jason...

Chapter 3 Cell Structure and Function PowerPoint® Lecture Slides prepared by Jason LaPres Lone Star College - North Harris Adapted by: Mr. Francis C. Rayo Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc.  3.1 The study of cells provides the foundation for understanding human physiology Copyright © 2010 Pearson Education, Inc.  An Introduction to Cells Cell Theory Cells are the building blocks of all plants and animals All cells come from the division of preexisting cells Cells are the smallest units that perform all vital physiological functions Each cell maintains homeostasis at the cellular level Copyright © 2010 Pearson Education, Inc.  The Study of Cells Cytology Study of structure and function of cells Cytology depends on seeing cells Light microscopy (LM) Electron microscopy (EM) Scanning EM (SEM) Transmission EM (TEM) Copyright © 2010 Pearson Education, Inc. The Diversity of Cells in the Human Body Figure 1.3 Copyright © 2010 Pearson Education, Inc.  An Overview of Cell Anatomy A cell is surrounded by a watery medium known as the extracellular fluid (interstitial fluid) Plasma membrane (cell membrane) separates cytoplasm from the extracellular fluid Cytoplasm: Cytosol = liquid Intracellular structures collectively known as organelles Copyright © 2010 Pearson Education, Inc. The Anatomy of a Model Cell Figure 2.3 Copyright © 2010 Pearson Education, Inc.  3.2 The plasma membrane separates the cell from its surrounding environment and performs various functions Copyright © 2010 Pearson Education, Inc.  Plasma Membrane Functions of the Plasma Membrane Physical isolation: Barrier Regulation of exchange with the environment: Ions and nutrients enter Wastes are eliminated and cellular products are released Sensitivity to the environment: Extracellular fluid composition Chemical signals Structural support: Anchors cells and tissues Copyright © 2010 Pearson Education, Inc.  Membrane Lipids Double layer of phospholipid molecules Hydrophilic heads — toward watery environment, both sides Hydrophobic fatty-acid tails — inside membrane Barrier to ions and water — soluble compounds Copyright © 2010 Pearson Education, Inc.  Membrane Lipids Copyright © 2010 Pearson Education, Inc.  Membrane Lipids Integral Proteins Extend across lipid bilayer; most are glyco-proteins; serve as either channels (pores), transporters (carriers), receptors (recognitions sites) or enzymes Peripheral Proteins Bound to inner or outer surface of the membrane; serve as cytoskeletal anchors Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Membrane Carbohydrates Glycoproteins and glycolipids Extend outside cell membrane Form sticky “sugar coat” (glycocalyx) Functions of the glycocalyx Lubrication and protection Anchoring and locomotion Specificity in binding (receptors) Recognition (immune response) Copyright © 2010 Pearson Education, Inc.  Intercellular Junctions Connect adjacent cell membranes Three types: Tight junctions prevent movement of substances in between cells, like caulking between tiles Desmosomes are structural reinforcement, like superglue Gap junctions allow ions to pass from cell to cell for communication (CELL PHONES!!) Copyright © 2010 Pearson Education, Inc.  The Plasma Membrane Figure 3.3 Copyright © 2010 Pearson Education, Inc. 3.3 Diffusion and filtration are passive transport mechanisms facilitating membrane passage Copyright © 2010 Pearson Education, Inc.  Membrane Transport The plasma (cell) membrane is a barrier, but Nutrients must get in Products and wastes must get out Permeability determines what moves in and out of a cell, and a membrane that Lets nothing in or out is impermeable Lets anything pass is freely permeable Restricts movement is selectively permeable Copyright © 2010 Pearson Education, Inc.  Membrane Transport Plasma membrane is selectively permeable Allows some materials to move freely Restricts other materials Selective permeability restricts materials based on Size Electrical charge Molecular shape Lipid solubility Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc.  Membrane Transport Transport through a plasma membrane can be Active (requiring energy and ATP) Passive (no energy required) Diffusion (passive) Carrier-mediated transport (passive or active) Vesicular transport (active) Copyright © 2010 Pearson Education, Inc.  Diffusion Diffusion Molecules mix randomly Solute spreads through solvent Eliminates concentration gradient Solutes move down a concentration gradient Diffusion of oxygen and carbon dioxide through the cell membranes; cellular respiration Copyright © 2010 Pearson Education, Inc.  Diffusion Figure 3-4 Copyright © 2010 Pearson Education, Inc.  Diffusion Diffusion Across Plasma Membranes Can be simple or channel mediated: Materials that diffuse through plasma membrane by simple diffusion: lipid-soluble compounds (alcohols, fatty acids, and steroids) dissolved gases (oxygen and carbon dioxide) Materials that pass through transmembrane proteins (channels): are water-soluble compounds are ions Copyright © 2010 Pearson Education, Inc.  Diffusion Across the Plasma Membrane Figure 3-5 Copyright © 2010 Pearson Education, Inc.  Diffusion Osmosis: A Special Case of Diffusion Osmosis is the diffusion of water across the cell membrane More solute molecules, lower concentration of water molecules Membrane must be freely permeable to water, selectively permeable to solutes Water molecules diffuse across membrane toward solution with more solutes Volume increases on the side with more solutes Copyright © 2010 Pearson Education, Inc.  Diffusion Osmosis: A Special Case of Diffusion Osmotic pressure: Is the force of a concentration gradient of water Equals the force (hydrostatic pressure) needed to block osmosis Copyright © 2010 Pearson Education, Inc.  Diffusion Osmolarity and Tonicity The osmotic effect of a solute on a cell: Two fluids may have equal osmolarity but different tonicity Isotonic (iso- = same, tonos = tension): A solution that does not cause osmotic flow of water in or out of a cell Hypotonic (hypo- = below): Has less solutes and loses water through osmosis Hypertonic (hyper- = above): Has more solutes and gains water by osmosis Copyright © 2010 Pearson Education, Inc.  Diffusion Osmolarity and Tonicity A cell in a hypotonic solution: Gains water Ruptures (hemolysis of red blood cells) A cell in a hypertonic solution: Loses water Shrinks (crenation of red blood cells) Copyright © 2010 Pearson Education, Inc. Effects of Osmosis Across Plasma Membranes Figure 3-7 Copyright © 2010 Pearson Education, Inc.  Filtration Hydrostatic pressure pushes on water Water crosses membrane Solute follows water Filtration initiates urine formation Copyright © 2010 Pearson Education, Inc.  3-4 Carrier-mediated and vesicular transport mechanisms also facilitate membrane passage Copyright © 2010 Pearson Education, Inc. Carrier-Mediated Transport Carrier-mediated transport of ions and organic substrates Facilitated diffusion Active transport Characteristics Specificity: One transport protein, one set of substrates Saturation limits: Rate depends on transport proteins, not substrate Regulation: Cofactors such as hormones Copyright © 2010 Pearson Education, Inc. Carrier-Mediated Transport Cotransport Two substances move in the same direction at the same time Countertransport One substance moves in while another moves out Copyright © 2010 Pearson Education, Inc. Carrier-Mediated Transport Facilitated diffusion Passive Carrier proteins transport molecules too large to fit through channel proteins (glucose, amino acids): Molecule binds to receptor site on carrier protein Protein changes shape, molecules pass through Receptor site is specific to certain molecules Copyright © 2010 Pearson Education, Inc. Carrier-Mediated Transport Figure 3-8 Copyright © 2010 Pearson Education, Inc. Carrier-Mediated Transport Active Transport Active transport proteins: Move substrates against concentration gradient Require energy, such as ATP Ion pumps move ions (Na+, K+, Ca2+, Mg2+) Exchange pump countertransports two ions at the same time Copyright © 2010 Pearson Education, Inc.  Carrier-Mediated Transport Active Transport Sodium–potassium exchange pump: Active transport, carrier mediated: sodium ions (Na+) out, potassium ions (K+) in 1 ATP moves 3 Na+ and 2 K+ Maintains resting membrane potential in many cells Copyright © 2010 Pearson Education, Inc.  The Sodium–Potassium Exchange Pump Figure 3-9 Copyright © 2010 Pearson Education, Inc.  Vesicular Transport Materials move into or out of cell in vesicles Endocytosis (endo- = inside) is active transport using ATP: Receptor mediated Pinocytosis Phagocytosis Exocytosis (exo- = outside): Granules or droplets are released from the cell Copyright © 2010 Pearson Education, Inc.  Receptor-Mediated Endocytosis Figure 3-10 Copyright © 2010 Pearson Education, Inc.  Phagocytosis and Exocytosis Figure Figure 3-11 3-11 Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. 3-5 Organelles within the cytoplasm performs specific functions Copyright © 2010 Pearson Education, Inc.  Cytosol and Organelles All materials inside the cell and outside the nucleus Cytosol (fluid): Dissolved materials: nutrients, ions, proteins, and waste products High potassium/low sodium High protein High carbohydrate/low amino acid and fat Organelles: Structures with specific functions Copyright © 2010 Pearson Education, Inc.  The Organelles Membranous Organelles Covered with plasma membrane Isolated from cytosol Include the endoplasmic reticulum (ER), the Golgi apparatus, lysosomes, peroxisomes, and mitochondria Non-membranous Organelles No membrane Direct contact with cytosol Include the cytoskeleton, microvilli, centrioles, cilia, ribosomes, and proteasomes Copyright © 2010 Pearson Education, Inc.  Organelles Non-membranous Organelles The cytoskeleton — structural proteins for shape and strength: Microfilaments Intermediate filaments Microtubules Copyright © 2010 Pearson Education, Inc.  The Cytoskeleton Figure 3-12 Copyright © 2010 Pearson Education, Inc.  The Organelles The Cytoskeleton Microvilli: Increase surface area for absorption Attach to cytoskeleton Centrioles in the centrosome: Centrioles form spindle apparatus during cell division Centrosome: cytoplasm surrounding centriole Cilia: Small hair-like extensions Cilia move fluids across the cell surface Copyright © 2010 Pearson Education, Inc.  The Organelles Ribosomes Build polypeptides in protein synthesis Two types: Free ribosomes in cytoplasm: manufacture proteins for cell Fixed ribosomes attached to ER: manufacture proteins for secretion Proteasomes Contain enzymes (proteases) Disassemble damaged proteins for recycling Copyright © 2010 Pearson Education, Inc.  The Organelles Membranous Organelles Five types of membranous organelles: Endoplasmic reticulum (ER) Golgi apparatus Lysosomes Peroxisomes Mitochondria Copyright © 2010 Pearson Education, Inc.  The Organelles Endoplasmic Reticulum (ER) Functions: Synthesis of proteins, carbohydrates, and lipids Storage of synthesized molecules and materials Transport of materials within the ER Detoxification of drugs or toxins Copyright © 2010 Pearson Education, Inc.  The Organelles Endoplasmic Reticulum (ER) Smooth endoplasmic reticulum (SER): No ribosomes attached Synthesizes lipids and carbohydrates: phospholipids and cholesterol (membranes) steroid hormones (reproductive system) glycerides (storage in liver and fat cells) glycogen (storage in muscles) Copyright © 2010 Pearson Education, Inc.  The Organelles Endoplasmic Reticulum (ER) Rough endoplasmic reticulum (RER): Surface covered with ribosomes: active in protein and glycoprotein synthesis folds polypeptide protein structures encloses products in transport vesicles Copyright © 2010 Pearson Education, Inc. The Endoplasmic Reticulum Figure 3-13 Copyright © 2010 Pearson Education, Inc. Organelles and the Cytoplasm Golgi Apparatus Vesicles enter forming face and exit maturing face: Secretory vesicles: modify and package products for exocytosis Membrane renewal vesicles: add or remove membrane components Lysosomes: carry enzymes to cytosol Copyright © 2010 Pearson Education, Inc.  The Golgi Apparatus Figure 3-14 Copyright © 2010 Pearson Education, Inc.  The Organelles Lysosomes Powerful enzyme-containing vesicles Functions of Lysosomes Clean up inside cells: Break down large molecules Attack bacteria Recycle damaged organelles Eject wastes by exocytosis Autolysis Auto- = self, lysis = break Self-destruction of damaged cells: lysosome membranes break down digestive enzymes are released cell decomposes cellular materials recycle Copyright © 2010 Pearson Education, Inc.  The Organelles Peroxisomes Are enzyme-containing vesicles: Break down fatty acids, organic compounds Produce hydrogen peroxide (H2O2) Replicate by division Copyright © 2010 Pearson Education, Inc.  The Organelles Mitochondria Have smooth outer membrane and inner membrane with numerous folds (cristae) Matrix: Fluid around cristae Mitochondrion takes chemical energy from food (glucose): Produces energy molecule ATP Copyright © 2010 Pearson Education, Inc.  The Organelles Mitochondria Aerobic metabolism (cellular respiration) Mitochondria use oxygen to break down food and produce ATP glucose + oxygen + ADP → carbon dioxide + water + ATP Glycolysis: glucose to pyruvic acid (in cytosol) Tricarboxylic acid cycle (TCA cycle): pyruvic acid to CO2 (in matrix) Electron transport chain inner mitochondrial membrane Copyright © 2010 Pearson Education, Inc.  The Organelles Figure 3-15 Copyright © 2010 Pearson Education, Inc.  3-6 The nucleus contains DNA and enzymes essential for controlling cellular activities Copyright © 2010 Pearson Education, Inc.  Nuclear Structure and Contents Nucleus Largest organelle The cell’s control center Nuclear Envelope Double membrane around the nucleus Perinuclear Space Between the two layers of the nuclear envelope Nuclear Pores Communication passages Copyright © 2010 Pearson Education, Inc.  The Nucleus Figure 3-16 Copyright © 2010 Pearson Education, Inc.  Nuclear Structure and DNA Contents All information to build and run organisms Nucleoplasm Fluid containing ions, enzymes, nucleotides, and some RNA Nucleoli Are related to protein production Are made of RNA, enzymes, and histones Synthesize rRNA and ribosomal subunits Chromatin Loosely coiled DNA (cells not dividing) Chromosomes Tightly coiled DNA (cells dividing) Copyright © 2010 Pearson Education, Inc.  Chromosome Structure Figure 3-17 Copyright © 2010 Pearson Education, Inc.  Information Storage in the Nucleus DNA Instructions for every protein in the body Gene DNA instructions for one protein Genetic Code The chemical language of DNA instructions: Sequence of bases (A, T, C, G) Triplet code: 3 bases = 1 amino acid Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc.  3-7 DNA controls protein synthesis, cell structure, and cell function Copyright © 2010 Pearson Education, Inc.  Protein Synthesis The Role of Gene Activation in Protein Synthesis The nucleus contains chromosomes Chromosomes contain DNA DNA stores genetic instructions for proteins Proteins determine cell structure and function Copyright © 2010 Pearson Education, Inc.  Protein Synthesis Transcription Copies instructions from DNA to mRNA (in nucleus) Translation Ribosome reads code from mRNA (in cytoplasm) Assembles amino acids into polypeptide chain Processing By RER and Golgi apparatus produce protein Copyright © 2010 Pearson Education, Inc.  Transcription A gene is transcribed to mRNA in three steps Gene activation DNA to mRNA RNA processing Copyright © 2010 Pearson Education, Inc.  Transcription Figure 3-18 Copyright © 2010 Pearson Education, Inc.  Protein Synthesis Translation mRNA moves: From the nucleus through a nuclear pore mRNA moves: To a ribosome in cytoplasm Surrounded by amino acids mRNA binds to ribosomal subunits: tRNA delivers amino acids to mRNA Copyright © 2010 Pearson Education, Inc.  Protein Synthesis Translation tRNA anticodon binds to mRNA codon 1 mRNA codon translates to 1 amino acid Enzymes join amino acids with peptide bonds Polypeptide chain has specific sequence of amino acids At stop codon, components separate Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc. Why is uracil present in RNA and not DNA? One of the four nucleobases in DNA's nucleic acid, represented by the letters G-C-A-T, is thymine. This is so that the DNA repair enzymes may recognize thymine rather than uracil. Because thymine has a higher resistance to photochemical mutation and makes the genetic code more durable, DNA uses it instead of uracil. The fact that uracil is present in RNA and not DNA contributes to the ability of RNA to be degraded easily. This allows the cell to change which genes are being expressed, as the older RNAs do not stick around for very long. Copyright © 2010 Pearson Education, Inc.  Translation Figure 3-19 Copyright © 2010 Pearson Education, Inc.  Translation Figure 3-19 Copyright © 2010 Pearson Education, Inc.  Translation Figure 3-19 Copyright © 2010 Pearson Education, Inc. Copyright © 2010 Pearson Education, Inc.  3-8 Stages of a cell’s life cycle include interphase, mitosis, and cytokinesis Copyright © 2010 Pearson Education, Inc.  A Cell’s Life Cycle Most of a cell’s life is spent in a nondividing state (interphase) Body (somatic) cells divide in three stages DNA replication duplicates genetic material exactly Mitosis divides genetic material equally Cytokinesis divides cytoplasm and organelles into two daughter cells Copyright © 2010 Pearson Education, Inc.  The Cell Life Cycle Figure 3-20 Copyright © 2010 Pearson Education, Inc.  Interphase The Nondividing Period G1 phase — cell growth, organelle duplication, protein synthesis S phase — DNA replication and histone synthesis G2 phase — finishes protein synthesis and centriole replication Copyright © 2010 Pearson Education, Inc.  DNA Replication Figure 3-21 Copyright © 2010 Pearson Education, Inc.  Mitosis Divides duplicated DNA into two sets of chromosomes DNA coils tightly into chromatids Chromatids connect at a centromere Copyright © 2010 Pearson Education, Inc.  Mitosis Prophase Centriole pairs move to cell poles Microtubules (spindle fibers) extend between centriole pairs Nuclear envelope disappears Metaphase Chromosomes align in a central plane (metaphase plate) Anaphase Microtubules pull chromosomes apart Daughter chromosomes group near centrioles Telophase Nuclear membranes reform Chromosomes uncoil Nucleoli reappear Cell has two complete nuclei Copyright © 2010 Pearson Education, Inc.  Interphase, Mitosis, and Cytokinesis Figure 3-22 Copyright © 2010 Pearson Education, Inc.  Interphase, Mitosis, and Cytokinesis Figure 3-22 Copyright © 2010 Pearson Education, Inc.  Interphase, Mitosis, and Cytokinesis Cytokinesis Division of the cytoplasm: Cleavage furrow around metaphase plate Membrane closes, producing daughter cells Copyright © 2010 Pearson Education, Inc.  3-9 Tumors and cancers are characterized by abnormal cell growth and division Copyright © 2010 Pearson Education, Inc.  Tumors and Cancers Abnormal cell growth Tumors (also called, neoplasm) Benign: Encapsulated Malignant: Invasion Metastasis Cancer — Disease that results from a malignant tumor Copyright © 2010 Pearson Education, Inc.  3-10 Differentiation is cellular specialization as a result of gene activation or repression Copyright © 2010 Pearson Education, Inc.  Cell Differentiation All cells carry complete DNA instructions for all body functions Cells specialize or differentiate To form tissues (liver cells, fat cells, and neurons) By turning off all genes not needed by that cell All body cells, except sex cells, contain the same 46 chromosomes Differentiation depends on which genes are active and which are inactive Copyright © 2010 Pearson Education, Inc.