Chapt04lecture
- 1. Essentials of Biology Sylvia S. Mader Michael Windelspecht Chapter 4 Inside the Cell Lecture Outline Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. See separate FlexArt PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes.
- 2. 4.1 Cells Under the Microscope • Cells Are extremely diverse Nearly all require a microscope to be seen Each type in our body is specialized for a particular function • Light microscope Invented in 17th century Limited by properties of light • Electron microscope Invented in 1930s Overcomes limitation by using beam of electrons
- 3. Figure 4.1 Using microscopes to see cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. LM of Euglena SEM of spiderling Scientist using a light microscope. Scientist using an electron microscope. TEM of human lymphocyte (TEM, lymphocyte): © Dr. Gopal Murti/Visuals Unlimited; (electron microscope): © Inga Spence/Visuals Unlimited; (light microscope): © Corbis Images/Jupiter Images RF; (Euglena): © Tom Adams/Visuals Unlimited; (SEM, spider): © Science Photo Library.Getty RF
- 4. Figure 4.2 Relative sizes of some living things and their components Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. unaided eye electron microscope 1 km100 m10 m1 m0.1 m1 cm1 mm100 nm10 nm1 nm0.1 nm mouse most bacteria viruses proteins amino acids atom s ant human blue whale chloroplast light microscope plant and animal cells human egg frog egg 1 µm 10 µm 100 µm
- 5. • Why are cells so small? Need surface areas large enough for entry and exit of materials Surface-area-to-volume ratio Small cells have more surface area for exchange Adaptations to increase surface area • Microvilli in the small intestine increase surface area for absorption of nutrients
- 6. 4.2 The Two Main Types of Cells • Cell theory All organisms are composed of cells All cells come only from preexisting cells • All cells have a plasma membrane Encloses cytoplasm and genetic material • 2 main types of cells Based on organization of genetic material 1. Prokaryotic cells – lack membrane-bounded nucleus 2. Eukaryotic cells – have nucleus housing DNA
- 7. Figure 4.3 Comparison of prokaryotic cells and eukaryotic cells Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Prokaryotic cell: simple internal structure Eukaryotic cell: complex internal structure cell flagella
- 8. • Prokaryotic cells Organisms from the domains Bacteria and Archaea Generally smaller and simpler in structure than eukaryotic cells • Allows them to reproduce very quickly and effectively Extremely successful group of organisms Bacteria • Well known because some cause disease • Others have roles in the environment • Some are used to manufacture chemicals, food, drugs, etc.
- 9. • Bacterial structure Cytoplasm surrounded by plasma membrane and cell wall • Sometimes a capsule – protective layer • Plasma membrane is the same as eukaryotes Cell wall maintains the shape of a cell DNA – single coiled chromosome located in nucleoid (region – not membrane enclosed) Ribosomes – site of protein synthesis Appendages • Flagella – propulsion • Fimbriae – attachment to surfaces • Conjugation pili – DNA transfer
- 10. Figure 4.4 Prokaryotic cell Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (right); © Ralph A. Slepecky/Visuals Unlimited fimbriae hair like bristles that allow adhesion to surfaces conjugation pilus elongated, hollow appendage used to transfer DNA to other cells capsule gel-like coating outside the cell wall nucleoid location of the bacterial chromosome ribosome site of protein synthesis flagellum rotating filament that propels the cell cytoplasm semifluid solution surrounded by the plasma membrane; contains nucleoid and ribosomes plasma membrane sheet that surrounds the cytoplasm and regulates entrance and exit of molecules cell wall structure that provides support and shapes the cell
- 11. 4.3 The Plasma Membrane • Marks boundary between outside and inside of a cell • Regulates passage in and out of a cell • Phospholipid bilayer with embedded proteins Polar heads of phospholipids face into watery medium Nonpolar tails face each other • Fluid-mosaic model – pattern that varies
- 12. Figure 4.5 A model of the plasma membrane Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. carbohydrate chain glycoprotein cholesterol hydrophobic phospholipid hydrophilic hydrophilic polar head nonpolar tail Outside of cell Inside of cell external membrane surface cytoskeleton filaments protein molecule phospholipid bilayer internal membrane surface
- 13. • Membrane proteins Channel proteins • Form tunnel for specific molecules Figure 4.6a Membrane protein diversity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. Channel protein
- 14. Transport proteins •Involved in passage of molecules through the membrane, sometimes requiring input of energy Figure 4.6b Membrane protein diversity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b. Transport protein
- 15. Cell recognition proteins •Enable our body to distinguish between our own cells and cells of other organisms Figure 4.6c Membrane protein diversity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. c. Cell recognition protein
- 16. Receptor proteins • Allow signal molecules to bind, causing a cellular response Figure 4.6d Membrane protein diversity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. d. Receptor protein
- 17. Enzymatic proteins •Directly participate in metabolic reactions Figure 4.6e Membrane protein diversity Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. e. Enzymatic protein
- 18. Junction proteins •Form junctions between cells •Cell-to-cell adhesion and communication Figure 4.6f Membrane protein diversity f. Junction proteins Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 19. 4.4 Eukaryotic cells • Protists, fungi, plants, and animals • Have a membrane-bounded nucleus housing DNA • Much larger than prokaryotic cells • Compartmentalized and contain organelles • 4 categories of organelles: 1. Nucleus and ribosomes 2. Endomembrane system 3. Energy-related 4. Cytoskeleton
- 20. Figure 4.7 Structure of typical animal cell Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a); © Dr. Dennis Kunkel/Visuals Unlimited microtubules chromatin nucleolus a. ×10,000 vesicle rough ER Golgi apparatus plasma membrane cytoplasm chromatin nucleolus nucleus: smooth ER lysosome mitochondrion b. vesicle formation centrioles (in centrosome) ribosome (attached to rough ER) ribosome (in cytoplasm) polyribosome (in cytoplasm) cytoskeleton: nuclear pore plasma membrane nuclear envelope endoplasmic reticulum nuclear envelope filaments
- 21. Figure 4.8 Structure of a typical plant cell Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. mitochondrion chloroplast central vacuole rough ER smooth ERcell wall plasma membrane Golgi apparatus cytoplasm cell wall of adjacent cell cytoskeleton: filaments microtubule chromatin nucleolus nucleus:centrosome mitochondrion nucleus chloroplast a. × 7,700 cell wall central vacuole ribosome (in cytoplasm) ribosome (attached to rough ER) nuclear envelope nuclear pore plasma membrane b. (a): © Newcomb/Wergin/Biological Photo Service
- 22. 1. Nucleus and ribosomes Nucleus • Stores genetic information • Chromatin – diffuse DNA, protein, some RNA Prior to cell division, DNA compacts into chromosomes • DNA organized into genes which specify a polypeptide Relayed to ribosome using messenger RNA (mRNA) • Nucleolus – region where ribosomal RNA (rRNA) is made • Nuclear envelope – double membrane Nuclear pores permit passage in and out
- 23. Figure 4.9 Structure of the nucleus Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. nuclear pores SEM of freeze-fractured nuclear envelope ER lumen nucleoplasm chromatin nucleolus nuclear envelope outer membrane inner membrane (right): Courtesy E.G. Pollock endoplasmic reticulum ribosome
- 24. Ribosomes • Carry out protein synthesis in the cytoplasm • Found in both prokaryotes and eukaryotes • Composed of 2 subunits • Mix of proteins and ribosomal RNA (rRNA) • Receive mRNA as instructions sequence of amino acids in a polypeptide • In eukaryotes, Some ribosomes free in cytoplasm Many attached to endoplasmic reticulum
- 25. Figure 4.10 The nucleus, ribosomes, and endoplasmic reticulum (ER) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. receptor ribosome Cytoplasm nuclear pore ribosome Nucleus ribosome ER membrane Endoplasmic reticulum large subunit 1 2 3 4 DNA mRNA mRNA is produced in the nucleus but moves through a nuclear pore into the cytoplasm. In the cytoplasm, the mRNA and ribosomal subunits join, and polypeptide synthesis begins. lumen of the ER If a ribosome attaches to a receptor on the ER, the polypeptide enters the lumen of the ER. At termination, the polypeptide becomes a protein. The ribosomal subunits disengage, and the mRNA is released. polypeptide protein small subunit
- 26. 1. Endomembrane system Consists of nuclear envelope, membranes of endoplasmic reticulum, Golgi apparatus, and vesicles Helps compartmentalize cell • Restricts certain reactions to specific regions Transport vesicles carry molecules from one part of the system to another
- 27. • Endoplasmic reticulum Complicated system of membranous channels and saccules Physically continuous with outer membrane of nuclear envelope Rough ER • Studded with ribosomes • Modifies proteins in lumen • Forms transport vesicles going to Golgi apparatus Smooth ER • Continuous with rough ER • No ribosomes • Function depends on cell Produces testosterone, detoxifies drugs
- 28. Figure 4.11 Endoplasmic reticulum (ER) Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. rough ER ribosomes smooth ER nuclear envelope © R. Bolender and D. Fawcett/Visuals Unlimited
- 29. • Golgi apparatus Stack of flattened saccules Transfer station Receives vesicles from ER Modifies molecules Sorts and repackages for new destination • Some are lysosomes • Lysosomes Vesicles that digest molecules or portions of the cell Digestive enzymes Tay-Sachs disease
- 30. Figure 4.12 Endomembrane system Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. smooth ER synthesizes lipids and performs other functions. transport vesicles from smooth ER lysosomes digest molecules or old cell parts. incoming vesicles bring substances into the cell. secretory vesicles fuses with the plasma membrane as secretion occurs. Golgi apparatus modifies lipids and proteins; sorts them and packages them in vesicles. transport vesicles from rough ER rough ER synthesizes proteins and packages them in
- 31. • Vacuoles Membranous sacs Larger than vesicles Rid a cell of excess water Digestion Storage • Plant pigments • Animal adipocytes
- 32. Figure 4.13 Vacuoles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a. b. c. ×7,700 ×400 vacuoles 80 0 a: © Roland/Birke/Peter Arnold/Photolibrary; b: © Newcomb/Wergin/Biological Photo Service; c: © The McGraw Hill Companies, Inc./Al Telser, photographer
- 33. 1. Energy-related organelles Chloroplasts • Use solar energy to synthesize carbohydrates • Only in plants • Three-membrane system Double membrane enclosing stroma • Thylakoids formed from third membrane Thylakoid membrane contains pigments that capture solar energy • Endosymbiosis – origin of chloroplasts Chloroplasts have their own DNA and ribosomes
- 34. Figure 4.14a Chloroplast structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. a: © Dr. George Chapman/Visuals Unlimited stroma granum ×35,000 a.
- 35. Figure 4.14b Chloroplast structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. thylakoid stroma granum outer membrane inner membrane b. double membrane thylakoid membrane thylakoid space
- 36. Mitochondria • Break down carbohydrates to produce adenosine triphosphate (ATP) • Found in BOTH plants and animals • Usually only visible under an electron microscope • Bounded by double membrane • Inner membrane folds called cristae Increase surface area • Inner membrane encloses matrix Mixture of enzymes assisting in carbohydrate breakdown Reactions permit ATP synthesis • Cellular respiration – needs oxygen, produces carbon dioxide • Endosymbiosis – also contains its own DNA and ribosomes
- 37. Figure 4.15 Mitochondrion structure Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. cristae b. ×70,000 a. outer membrane inner membrane matrix double membrane b: Courtesy Keith Porter
- 38. 1. Cytoskeleton Network of interconnected protein filaments and tubules Extends from the nucleus to the plasma membrane Only in eukaryotes Maintains cell shape With motor proteins, allows cell and organelles to move
- 39. • Microtubules Small, hollow cylinders Assembly controlled by centrosome Help maintain cell shape and act as trackways • Intermediate filaments Intermediate in size Ropelike assembly Run from nuclear envelope to plasma membrane
- 40. Figure 4.16 Microtubules Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. microtubule centrosome nucleus cell
- 41. •Actin filaments 2 chains of monomers twisted in a helix Forms a dense web to support the cell
- 42. Figure 4.17 Actin filaments Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. microvilli nucleus cell actin filaments
- 43. • Motor proteins Instrumental in allowing cellular movements Myosin • Interacts with actin • Cells move in amoeboid fashion • Muscle contraction Kinesin and dynein • Move along microtubules • Transport vesicles from Golgi apparatus to final destination
- 44. Figure 4.18b Motor proteins Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. microtubule kinesin b. Kinesin kinesin receptor vesicle moves, not microtubule ATP vesicle
- 45. • Centrioles Made of 9 sets of microtubule triplets Two centrioles lie at right angles In animal cells, not present in plant cells
- 46. Figure 4.19 Centrioles Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. centrosome one microtubule triplet one pair of centrioles in a centrosome (Left); © Don W. Fawcett/Photo Researchers, Inc
- 47. • Cilia and flagella Eukaryotes For movement of the cell or fluids past the cell Similar construction in both • 9+2 pattern of microtubules Cilia shorter and more numerous than flagella
- 48. Figure 4.20 Cilia and flagella Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b. Flagellum triplets Basal body dynein side arms TEM ×101,000 TEM ×350,000 Basal body cross section plasma membrane central microtubules microtubule doublet Flagellum cross section a. cilia in bronchial wall of lungs flagella of sperm a; (cilia): © Manfred Kage/Peter Arnold/Photolibrary; a(sperm): © David M. Phillips/Photo Researchers, Inc.; b (both): © William L. Dentler/Biological Photo Service
- 49. 4.5 Outside the Eukaryotic Cell • Plant cell walls Primary cell walls • Cellulose fibrils and noncellulose substances • Wall stretches when cell is growing Secondary cell walls • Forms inside primary cell wall • Woody plants • Lignin adds strength Plasmodesmata • Plant cells connected by numerous channels that pass through cell walls • For exchange of water and small solutes between cells
- 50. Figure 4.21 Plasmodesmata Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. cell wall plasmodesmata cell wall Cell 1 Cell 2 cell wall cytoplasm cytoplasm middle lamella plasmodesmata ×53,000 plasma membrane (Bottom): © E.H. Newcomb/Biological Photo Service
- 51. • Exterior cell surfaces in animals No cell wall Extracellular matrix (ECM) • Meshwork of fibrous proteins and polysaccharides • Collagen and elastin well-known proteins • Matrix varies – flexible in cartilage, hard in bone
- 52. Figure 4.22 Animal cell extracellular matrix Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. collagen polysaccharide cytoplasm elastic fiber receptor protein cytoskeleton filament
- 53. • Junctions between cells Adhesion junctions • Internal cytoplasmic plaques joined by intercellular filaments • Sturdy but flexible sheet of cells
- 54. Figure 4.23a Junctions between cells of the intestinal wall (Left); From Douglas E. Kelly, Journal of Cell Biology, 28 (1966:51). Reproduced by permission of The Rockefeller University Press Adhesion junction plasma membranes filaments of cytoskeleton intercellular space intercellular filaments Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
- 55. Tight junctions •Plasma membrane proteins attach to each other •Zipper-like •Cells of tissues that serve as barriers Figure 4.23b Junctions between cells of the intestinal wall Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. intercellular space plasma membranes tight junction proteins Tight junction
- 56. Gap junctions •Allow cells to communicate through plasma membrane channels •Lend strength while allowing small molecules and ions to pass through Figure 4.23c Junctions between cells of the intestinal wall Gap junction plasma membranes membrane channel intercellular space Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.