Chapter 2 Cytology Lecture Notes PDF

Cytology: The Study of Chapter 2 Cells 2-1  Human Body Intracellular Cells Body Fluids (42L)...

Cytology: The Study of Chapter 2 Cells 2-1  Human Body Intracellular Cells Body Fluids (42L) materials Extracellular Fluid Intracellular Fluid (ECF) plasma Fibers and crystals (ICF) (28L) (3L),lymph, interstitial fluid (11L) 2-2 Cells: Structural and Functional Units of Life Cell theory: structural building blocks, produced by division of preexisting cells, smallest structural units, perform all vital functions Function: formation of intercellular materials and fluids Form highly adapted to function Wide range of sizes and shapes 30-40 trillion, 200 types Surfaces: basal, lateral, and apical  General Functions Covering Lining Storage Movement Connection Defense Communication Reproduction 2-4  Cellular Diversity: Size Micrometer (μm): One- millionth of a meter (10-6) 10-15 micrometers in diameter Visible to the naked eye, about 100 µm RBC about 8 µm Ovum about 140 µm Neuron > 1 meter long 2-5  Copyright © The McG ra w-Hill Companies , Inc. Permission re quired for reproduction or dis play. Cellular Diversity: Cell Shapes 2-6 2-7 Basic Components: 2 - 8 Plasma membrane Nucleus Cytoplasm  The boundary between the ECF and the ICF Thickness:6-10 nm Selectively permeable Fluid mosaic model: protein icebergs floating in a phospholipid sea Function: Physical isolation Sensitivity: receptors Cell-to-cell communication, adhesion, structural support Plasma Regulation of passage of materials in and out Membrane 2-9 Plasma Membrane Composition Plasma Membrane Lipids Proteins Transmembrane/ Phospholipids Glycolipids Cholesterol (20%) Integral Peripheral (75%) (5-10%) Glycoprotein 2-11  Phospholipid Molecule Phospholipid bilayer Hydrophilic head Hydrophobic tail Selectively permeable 2-12  Functions of Membrane Proteins Receptor Transport/ Carrier Protein Enzyme Cell-identity Marker Channel Protein Cell-adhesion Molecule (CAM) 2-13  Major Types of Membrane Transport Membrane Transport Passive (down Active (up concentration concentration gradient) gradient) No ATP ATP required Simple Diffusion (nonpolar Facilitated Diffusion Primary Secondary molecules, water, Membrane protein Membrane protein Membrane protein ions) Glycocalyx Fuzzy, sugary coat on top of proteins and lipids Function: Protects Cell identity Binds tissues 2-15 Surface Extensions of Plasma Membrane Microvilli: absorption, increase surface area, microfilaments Cilia: movement of material over cell surface, microtubules Flagella: propulsion of sperm cells, microtubules Microvilli, Cilia, and Flagella 2-17 Cell Junctions Tight junctions: Interlocking proteins, prevent the passage of water and solutes Desmosome: Very strong, resistance to stretching and twisting Gap junctions: Connexons. Diffusion of ions, small molecules, and electrical impulses 2-18  Nucleus Largest organelle Control center: information needed to produce 100,000 different proteins Often mirrors the cell shape Uninucleate, multinucleate, or anucleate Nuclear envelope Nuclear pores Nucleoplasm Chromosomes Nucleolus(nucleoli): made up of RNA, enzymes, and other proteins. Synthesis of ribosomes 2-19  Organelles Cytosol/ ICF Cytoplasm Cytoskeleton Inclusions 2-20  Water (75-90%) Proteins (15-20%): Cytosol/ICF mostly enzymes, consistency Carbohydrates, lipids, amino acids, and ions: K+, Na+, Ca++, Cl- 2-21  Cytoskeleton Proteins organized as filaments and hollow tubules Types: omicrofilaments: actin ointermediate filaments othick filaments: myosin omicrotubules: tubulin Functions: Support cell Determine shape Organize contents Move substances Move cell Cell division 2-22 Inclusions Not essential to cell survival Stored cellular products: Pigments: melanin Fat droplets Glycogen Foreign bodies: Dust particles Viruses Intracellular bacteria 2-23  Mitochondria Endoplasmic reticulum: RER SER Membranous Peroxisomes Lysosomes Organelles Golgi complex Ribosomes Non-membranous Centrioles 2-24  Endoplasmic Reticulum (ER) Rough endoplasmic reticulum (RER) Studded with ribosomes Protein production Near the nucleus Smooth endoplasmic reticulum (SER) Detoxifies materials (alcohol, poisons, and drugs) Synthesizes steroids, carbohydrates, and phospholipids Stores Ca++  Golgi Complex/ Apparatus Stacks of cisternae Highly active in cells specialized in secretion Near nucleus Forming /Cis face→ RER Maturing/Trans face → Plasma membrane Function: Renewal and modification of plasma membrane Packaging enzymes for cytosol Synthesis and packaging of secretions Golgi vesicles: Become lysosomes To the plasma membrane. Exocytosis Secretory vesicles  Lysosomes Digestive enzymes in vesicles Function: Defense against disease. Endocytosis Cleanup, recycling, and waste removal by autophagy Self-destruction after cellular death by autolysis 2-27  Peroxisomes Function: Oxidize organic molecules to detoxify Convert hydrogen peroxide into water and oxygen by action of catalase Break down fatty acid molecules Abundant in liver and kidney 2-28  Mitochondria Function: Aerobic respiration. ATP production Outer membrane Inner membrane: Cristae Mitochondrial matrix Mitochondrial DNA (mtDNA) Abundant in muscle cells and sperm 2-29  Ribosomes Locations: Cytosol RER Nuclear envelope Nucleoli Mitochondria Function: Read genetic messages → Assemble amino acids → Synthesize proteins Composed of two subunits Types: Free: protein synthesis for use within cell Fixed: proteins destined to plasma membrane, export, or housed within lysosomes  Centrioles Microtubules organized in nine groups of three Found in centrosome Form the spindle apparatus during cell division Not found in RBC and skeletal muscle cells 2-31 The Cell Cycle 2-32 Interphase Most of the time for most cells First Gap Phase (G1) Growth, duplication of organelles Normal metabolic roles Non-dividing cells stay in G0 Synthesis Phase (S) DNA replication Second Gap Phase (G2) DNA proofreading 2-33 Mitosis Distribution of one copy of genetic information to each daughter cell Nuclear division to produce two identical nuclei Divided into four phases: Prophase Metaphase Anaphase Telophase  Early and Late Prophase : P for Puffy ball Chromatin (loosely coiled DNA + proteins + RNA) condenses into chromosomes Nuclear envelope breaks down Nucleolus disappears Formation of mitotic apparatus: spindle fibers connect to kinetochore 2-35  Organized structure of DNA and proteins (histones) Chromosomes Consist of 2 chromatids (elongated and identical strands of DNA) held at the center by a centromere 2-36 Anatomy of Chromosomes Telomere 2-37 Metaphase: M for Middle Anaphase: A for Apart Telophase: T for Two Chromosomes uncoil into chromatin Nuclear membrane reforms Nucleoli reform Mitotic apparatus disassembles 2-40  Division of cytoplasm Cytokinesis Begins in anaphase Cleavage furrow developed (contraction of cytoplasm by contracting actin filaments) Cell pinches into two identical daughter cells 2-41 Meiosis: Reproductive Cell Division Two successive stages of nuclear division Production of haploid gametes Meiosis I: Homologous chromosomes undergo pairing and crossing-over; two haploid cells Meiosis II: Four haploid cells 2-42 Aging and Cells Progressive alteration of body’s homeostatic adaptive responses to maintain normal conditions Changes in structure and function Increased vulnerability to environmental stress and disease Genetically programmed cessation of cell division, shortening of telomeres, build-up of free radicals, and intensified immune response 2-43