Cell Structure and Function PDF

UNIT 2 – ANIMAL ORGANIZATION: CELL STRUCTURE & FUNCTION  Did you know? Bacteria in our intestines make vitamins and keep us healthy Other bacteria make toxins that can contaminate foods that can sicken or even kill us Example: each year, about 265,000 people in the United States beco...

UNIT 2 – ANIMAL ORGANIZATION: CELL STRUCTURE & FUNCTION  Did you know? Bacteria in our intestines make vitamins and keep us healthy Other bacteria make toxins that can contaminate foods that can sicken or even kill us Example: each year, about 265,000 people in the United States become infected with toxin– producing E. coli What, Exactly, Is a Cell? Cell theory: one of the foundations of modern biology 1. Each organism consists of one or more cells. 2. The cell is the structural and functional unit of all organisms. A cell is the smallest unit of life, individually alive even as part of a multicelled organism. 3. All living cells arise by division of preexisting cells. 4. Cells contain hereditary material (DNA), which they pass to their offspring when they divide. How Do We See Cells? No one knew cells existed until microscopes were invented Discovery of the Cell 6  How Do We See Cells? electron microscopes light microscopes small molecules of life viruses mitochondria, most most molecules chloroplasts bacteria eukaryotic lipids carbohydrates proteins DNA cells human eye (no microscope) small animals largest organisms frog eggs © 2016 Cengage Learning; Louse, Edward S. Ross; Ant, Vladimir Davydov/iStock/360/Getty Images; Frog, © A Cotton Photo/Shutterstock; Rat, © Pakhnyushcha/Shutterstock; Goose, panbazil/Shutterstock.com; Boy, © Piotr Marcinski/Shutterstock; Giraffe, © Valerie Kalyuznnyy/Photos.com; Whale, Dorling Kindersley/Getty Images. Constraints on Cell Size Cells must be small to efficiently exchange materials with their environment Surface-to-volume ratio Relationship in which the volume of an object increases with the cube of the diameter, but the surface areas increases with the square of the diameter Limits cell size and influences cell shape Types of Cell Shapes 9 10 11 Types of Cells Types of Cells 49  Components of All Cells Plasma membrane Surrounds the cell and controls which substances move in and out (selectively permeable) Proteins embedded in a lipid bilayer or attached to one of its surfaces carry out membrane functions Cytoplasm Jellylike mixture of water, sugars, ions, and proteins Site of some or all of cell’s metabolism Organelle Structure that carries out a specialized metabolic function inside a cell All cells start out life with DNA Eukaryotic cells have a nucleus that contains DNA  Cell Membrane Structure Cell membrane Mosaic of proteins and lipids (mainly phospholipids) that functions as a selectively permeable barrier separating an internal environment A. In a watery fluid, phospholipids spontaneously line up into two layers: the hydrophobic tails cluster together, and the hydrophilic from an external one heads face outward, toward the fluid. This lipid bilayer forms the framework of all cell membranes. Many types of proteins intermingle among the lipids; a few that are typical of plasma membranes are shown opposite. Fluid mosaic model A cell membrane can be considered a two-dimensional fluid of mixed composition Membrane Proteins Cell membrane structure Organization of phospholipids in cell membranes Proteins associated with a membrane carry out most (A) and examples of common membrane proteins membrane functions (B–E). For clarity, these proteins are often modeled as blobs or geometric shapes; their structure can be extremely complex. B. Adhesion proteins fasten cells together or to external proteins. This one connects protein filaments inside the cell with external filaments in animal tissues. C. Receptor proteins trigger a change in cellular activity in response to a stimulus such as binding to a particular substance. This one occurs on cells of the immune system. D. Enzymes speed reactions at membranes. This one is part of a membrane-bound set of molecules that together break down drugs and other organic toxins. E. Transport proteins bind to molecules on one side of the membrane, and release them on the other side. This one transports glucose. Prokaryotic Cells Prokaryotes Domains Bacteria and Archaea Smallest and most metabolically diverse life Inhabit nearly all regions of biosphere Many archaeans are extremophiles © 2016 Cengage Learning; (A, B) © Biophoto Associates/Science Source; (C) © K.O. Stetter & R. Rachel, Univ. Regensburg; (D) Cryo-EM image of Haloquadratum walsbyi, isolated from Australia. Courtesy of Zhuo Li (City of Hope, Duarte, California, USA), Mike L. Dyall-Smith (Charles Sturt University, Australia), and Grant J. Jensem (California Institute of Technology, Pasadena, California, USA); (E) Biomedical Imaging Unit, Southhampton General Hospital/Science Photo Library; (F) Archivo Angels Tapias y Fabrice Confalonieri. Prokaryote Body Plan ❑ Cytoplasm ▪ Ribosomes Organelle of protein synthesis ▪ A circular DNA molecule in a nucleoid region ▪ May contain additional genes as plasmids ❑ Cell wall ▪ Semirigid but permeable structure that surrounds the plasma membrane of some cells ▪ Consists of peptides and polysaccharides (in bacteria) or proteins (in archaeans) ▪ In some bacteria, a sticky capsule of polysaccharides surrounds the cell wall Prokaryote Body Plan ❑ Surface extensions allow certain actions ❑ Pili ▪ Protein filaments used to help cells cling to or move across surfaces, or for plasmid transfer ❑ Flagella ▪ Long, slender cellular structures used for mobility  Biofilms Community of different types of microorganisms living within a shared mass of slime Provides various advantages to the community of organisms Often attached to solid surface  Eukaryotic Cells Figure 10 Common components of eukaryotic cells.. An animal cell is illustrated here. © 2016 Cengage Learning 1. The nucleus protects and controls access to the cell’s DNA. 2. Vesicles form by budding from other components of the endomembrane system or from the plasma membrane. Some transport substances among organelles of the ER, and to and from the plasma membrane. Others store or break down substances. 3. Ribosomes attached to rough endoplasmic reticulum (ER) assemble polypeptides that thread into the ER’s interior, where they take on tertiary structure and assemble with other polypeptides. 4. Many proteins made in rough ER migrate through the ER compartment to smooth ER. Some of these proteins stay in smooth ER, as enzymes that assemble lipids and break down carbohydrates, wastes, and toxins. Others are packaged in vesicles for transport to Golgi bodies. 5. Golgi bodies modify proteins and lipids, then sort and repackage the finished molecules into new vesicles. Some of the new vesicles become lysosomes. Others carry proteins to the plasma membrane for insertion into the lipid bilayer or secretion. 6. Mitochondria specialize in efficient production of ATP.  The Nucleus The nucleus protects and controls access to the cell’s DNA. Pores, receptors, and transport proteins in the nuclear envelope control the movement of molecules into and out of the nucleus Nuclear envelope - A double membrane that constitutes the outer boundary of the nucleus Word Match Activity Match the genetic terms to their corresponding parts of the illustration. base pair cell chromosome DNA (Deoxyribonucleic Acid) double helix* genes nucleus Illustration Source: Talking Glossary of Genetic Terms http://www.genome.gov/glossary/ Word Match Activity base pair nucleus chromosome cell chromosome DNA cell (Deoxyribonucleic Acid) double helix* genes nucleus base pair (double helix) DNA Illustration Source: Talking Glossary of Genetic Terms http://www.genome.gov/glossary/ genes 61  Concepts describes how some traits are passed from parents to their children. The traits are expressed by , which are small sections of DNA that are coded for specific traits. Genes are found on ___. Humans have two sets of _ (hint: a number) chromosomes—one set from each parent.  Genetic Concepts Heredity describes how some traits are passed from parents to their children. The traits are expressed by genes, which are small sections of DNA that are coded for specific traits. Genes are found on chromosomes. Humans have two sets of 23 chromosomes—one set from each parent. Molecular Visualizations of DNA 64 The Endomembrane System Includes rough and smooth endoplasmic reticulum, vesicles, and Golgi bodies Endomembrane system Series of interacting organelles between the nucleus and plasma membrane Makes and modifies lipids and proteins Recycles molecules and particles such as worn-out cell parts Inactivates toxins Endoplasmic reticulum (ER) A continuous system of sacs and tubes that is an extension of the nuclear envelope Rough ER is studded with ribosomes (for protein production) Smooth ER has no ribosomes The Endomembrane System Vesicle Small, membrane-enclosed, saclike organelle Stores, transports, or degrades its contents Vacuole A fluid-filled organelle that isolates or disposes of wastes, debris, or toxic materials Lysosome Vesicle with enzymes for intracellular digestion Peroxisome Enzyme-filled vesicle that breaks down amino acids, fatty acids, and toxic substances Golgi body Organelle that modifies polypeptides and lipids Sorts and packages the finished products into transport vesicles Bacteria-Like Organelles: Mitochondria and Chloroplasts Mitochondria and chloroplasts resemble bacteria and may have evolved from bacteria Mitochondrion Double-membraned organelle that produces ATP Chloroplast Organelle of photosynthesis Two membranes, one folded inside the other, form the ATP-making machinery of this eukaryotic organelle. The TEM shows a mitochondrion in a cell from bat pancreas. Each chloroplast has two outer membranes. Photosynthesis occurs at a third, much-folded inner membrane. TEM shows a chloroplast from a cell in a corn leaf. 69 The Cytoskeleton Dynamic system of protein filaments Supports, organizes, and moves eukaryotic cells and their internal structures Interacts with accessory proteins, such as motor proteins ❑Microtubules Cytoskeletal elements involved in movement Hollow filaments of tubulin subunits ❑Microfilaments Reinforcing cytoskeletal elements Fibers of actin subunits ❑Intermediate filaments Elements that lock cells and tissues together Motor Proteins Energy-using proteins that interact with cytoskeletal elements to move cells parts or the whole cell Example: Motor protein moves a vesicle along a microtubule Kinesin protein walking on microtubule © 2016 Cengage Learning; © ADVANCELL (Advanced In Vitro Cell Technologies; S.L.) www.advancell.com. Cilia Short, hairlike structures that project from the plasma membrane of some eukaryotic cells Coordinated beating stirs fluid, propels motile cells Moved by organized arrays of microtubules Example: clears particles from airways Flagella Whip back and forth to propel cells such as sperm through fluid Pseudopods Temporary protrusion that helps some eukaryotic cells move and engulf prey Moved by motor proteins attached to microfilaments that drag plasma membrane Example: amoebas Insert photo on page 57, bottom Extracellular Matrix (ECM) Complex mixture of molecules secreted by cells Supports cells and tissues Functions in cell signaling Cuticle Type of ECM secreted by cells at a body surface Found in plants and arthropods Cell wall ECM that protects, supports, and imparts shape Found in prokaryotes, plants, fungi and some protists  Cell Junctions Connect a cell to another cell or to the ECM Tight junction Array of fibrous proteins that joins epithelial cells and prevents fluids from leaking between them Adhering junction Anchors cells to each other or to the extracellular matrix Gap junction Channel across plasma membranes of adjoining cells Three types of cell junctions common in animal tissues: tight junctions, gap junctions, and adhering junctions. The micrograph shows how a profusion of tight junctions (green) seals abutting surfaces of kidney cell membranes to form a waterproof tissue. The DNA in each cell nucleus appears red. In plants, plasmodesmata connect the cytoplasm of adjoining cells Plasmodesmata Open channels that extend across the primary walls of adjoining cells Allow materials such as water, nutrients, and signaling molecules to flow through The Inner Life of a Cell 77  The Nature of Life Six properties characterize living things as different from nonliving things Make and use organic molecules of life Consist of one or more cells Self-sustaining biological processes such as metabolism Change over their lifetime (develop, mature, age) Use DNA as hereditary material when they reproduce Have the collective capacity to change over successive generations 79 Homework THANK YOU! References Johnson TR, Case CL. 1992. Laboratory experiments in microbiology. 3rd ed. California, USA: Benjamin/Cummings Publishing Co., Inc. Miller S, Harley J. 2012. ZOOLOGY. 8th ed. New York: McGraw-Hill Companies Perez et al. 2005. LABORATORY NOTES AND GUIDE in General Zoology. Manila: Centro Escolar University. ROWLEY JJ L, HOANG HD, DAU VQ, LE DTT, CAO TT. 2012. A new species of Leptolalax (Anura: Megophryidae) from central Vietnam. Zootaxa, 3321(1), 56. doi:10.11646/zootaxa.3321.1.4 10.11646/zootaxa.3321.1.4 Starr, C. 2015. Biology Today and Tomorrow ([edition unavailable]). Cengage Learning EMEA. Wise, E. 2023. Seeley’s Anatomy and Physiology Laboratory Manual. 13th ed. New York, McGraw Hill.