Ch 4 structure and function of cells


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Ch 4 structure and function of cells

  1. 1. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 4 Structure and Function of Cells
  2. 2. Cells Are the Basic Units of Life
  3. 3. 4.1 All organisms are composed of cells <ul><li>The cell theory states </li></ul><ul><ul><li>A cell is the basic unit of life </li></ul></ul><ul><ul><li>All living things are made up of cells </li></ul></ul><ul><ul><li>New cells arise only from preexisting cells </li></ul></ul>
  4. 4. Figure 4.2A The sizes of living things and their components
  5. 5. 4.2 Metabolically active cells are small in size <ul><li>Surface-area-to-volume ratio constrains increases in a cell’s size </li></ul><ul><ul><li>Actively metabolizing cells need to be small </li></ul></ul><ul><ul><li>Cells that specialize in absorption have modifications to increase the surface-area-to-volume ratio </li></ul></ul>
  6. 6. Figure 4.2B Surface-area-to-volume relationships
  7. 7. APPLYING THE CONCEPTS—HOW SCIENCE PROGRESSES 4.3 Microscopes allow us to see cells <ul><li>Compound light microscope </li></ul><ul><ul><li>Multiple lenses increase magnifying power </li></ul></ul><ul><ul><ul><li>A condenser lens focuses light through specimen </li></ul></ul></ul><ul><ul><ul><li>An objective lens magnifies the specimen’s image </li></ul></ul></ul><ul><ul><ul><li>An ocular lens magnifies the image into the eye </li></ul></ul></ul><ul><li>Electron microscope </li></ul><ul><ul><li>More magnifying power than light microscope </li></ul></ul><ul><ul><ul><li>Transmission electron microscope passes electrons through specimen </li></ul></ul></ul><ul><ul><ul><li>Scanning electron microscope collects and focuses electrons scattered by the specimen </li></ul></ul></ul>
  8. 8. Figure 4.3 Comparison of three microscopes
  9. 9. 4.4 Prokaryotic cells evolved first <ul><li>Prokaryotic cells </li></ul><ul><ul><li>Lack a membrane-bound nucleus </li></ul></ul><ul><ul><li>Smaller than eukaryotic cells </li></ul></ul><ul><ul><li>Have a single chromosome, semifluid cytoplasm, and thousands of ribosomes </li></ul></ul>
  10. 10. Figure 4.4B Prokaryotic cell structure
  11. 11. Figure 4.4A Size comparison of a eukaryotic cell and a prokaryotic cell
  12. 12. Archaea and Bacteria <ul><li>Two domains of prokaryotic cells </li></ul><ul><li>Different nucleic acid bases </li></ul><ul><li>Bacteria cause many diseases, but are also important in the environment for recycling nutrients </li></ul>
  13. 13. 4.5 Eukaryotic cells contain specialized organelles: An overview <ul><li>Eukaryotic cells are third domain of cells </li></ul><ul><li>Cytoskeleton - protein fibers that maintain cell shape </li></ul><ul><li>Have membrane-bound nucleus and organelles </li></ul><ul><ul><li>Endomembrane system: endoplasmic reticulum, Golgi apparatus, and lysosomes </li></ul></ul><ul><ul><li>Energy-related organelles : mitochondria and chloroplasts </li></ul></ul>
  14. 14. Figure 4.5A Animal cell anatomy
  15. 15. Figure 4.5B Plant cell anatomy
  16. 16. Protein Synthesis Is a Major Function of Cells
  17. 17. 4.6 The nucleus contains the cell’s genetic information <ul><li>Nucleus contains chromatin, a network of strands that condenses to form chromosomes </li></ul><ul><ul><li>Chromosomes contain DNA which carries genes, the units of heredity </li></ul></ul><ul><ul><li>Nucleolus - dark region of chromatin with ribosomal RNA (rRNA) </li></ul></ul><ul><ul><li>Nuclear envelope separates the nucleus from the cytoplasm, but has nuclear pores to permit passage of ribosomal subunits </li></ul></ul>
  18. 18. Figure 4.6 Anatomy of the nucleus
  19. 19. 4.7 The ribosomes carry out protein synthesis <ul><li>Ribosomes – non-membrane-bound particles where protein synthesis occurs </li></ul><ul><li>Endoplasmic reticulum (ER) – a membranous system where ribosomes attach and aid in protein synthesis </li></ul>
  20. 20. Figure 4.7 Function of ribosomes
  21. 21. 4.8 The endoplasmic reticulum synthesizes and transports proteins and lipids <ul><li>The ER attaches to the nuclear envelope </li></ul><ul><ul><li>Rough ER is studded with ribosomes that synthesize proteins </li></ul></ul><ul><ul><li>Smooth ER lacks proteins and is where lipids are made </li></ul></ul><ul><li>Transport vesicles carry proteins and lipids to Golgi apparatus for modification </li></ul>
  22. 22. Figure 4.8 Rough ER (RER) and smooth ER (SER)
  23. 23. 4.9 The Golgi apparatus modifies and repackages proteins for distribution <ul><li>One side is directed toward the ER and the other toward the cytoplasm </li></ul><ul><li>Golgi apparatus sorts and packages proteins and lipids in vesicles </li></ul><ul><ul><li>Vesicles are secreted from the cell membrane via exocytosis </li></ul></ul>
  24. 24. Figure 4.9 Golgi apparatus (gray-green) and transport vesicles
  25. 25. APPLYING THE CONCEPTS - HOW SCIENCE PROGRESSES 4.10 Pulse-labeling allows observation of the secretory pathway <ul><li>George Palade pulse-labeled the rough ER with radioactive amino acids to observe the pathway of protein secretion </li></ul>
  26. 26. Vesicles and Vacuoles Have Varied Functions
  27. 27. 4.11 Lysosomes digest macromolecules and cell parts <ul><li>Lysosomes - membrane-bound vesicles produced by the Golgi apparatus </li></ul><ul><ul><li>Important in recycling cellular material and digesting worn-out organelles </li></ul></ul><ul><ul><li>Tay Sachs disease – when a particular lysosomal enzyme is nonfunctional </li></ul></ul><ul><ul><ul><ul><li> Figure 4.11 Lysosome fusing with and destroying spent organelles </li></ul></ul></ul></ul>
  28. 28. 4.12 Peroxisomes break down long-chain fatty acids <ul><li>Peroxisomes - small, membrane-bound organelles resembling empty lysosomes </li></ul><ul><li>Contain enzymes to digest excess fatty acids </li></ul><ul><ul><li>Produces products used by mitochondria to make ATP </li></ul></ul><ul><li>Produce cholesterol and phospholipids found in brain and heart tissue </li></ul>
  29. 29. 4.13 Vacuoles have varied functions in protists and plants <ul><li>Vacuoles – membranous sacs larger than vesicles and usually store substances </li></ul><ul><ul><li>Example: toxic substances used in plant defense </li></ul></ul><ul><li>Central vacuole – found in plants, contains watery sap and maintains turgor pressure </li></ul><ul><ul><ul><li>Figure 4.13 Central vacuole of a plant cell </li></ul></ul></ul>
  30. 30. 4.14 The organelles of the endomembrane system work together <ul><li>Endomembrane system is a series of membranous organelles that work together and communicate via transport vesicles </li></ul><ul><ul><li>Includes: ER, Golgic apparatus, lysosomes and transport vesicles </li></ul></ul>
  31. 31. Figure 4.14 The organelles of the endomembrane system
  32. 32. A Cell Carries Out Energy Transformations
  33. 33. 4.15 Chloroplasts capture solar energy and produce carbohydrates <ul><li>Chloroplasts - type of plastid, an organelle bounded by a double membrane with a series of internal membranes separated by a ground substance </li></ul><ul><ul><li>Endosymbiotic theory - from eukaryotic cell engulfing a photosynthetic bacteria </li></ul></ul>
  34. 34. Figure 4.15 Chloroplast structure
  35. 35. 4.16 Mitochondria break down carbohydrates and produce ATP <ul><li>Mitochondria were also derived from bacteria and therefore have a double membrane </li></ul><ul><ul><li>Often called the powerhouse of the cell because they produce most of the ATP </li></ul></ul>
  36. 36. Figure 4.16 Mitochondrion structure
  37. 37. APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 4.17 Malfunctioning mitochondria can cause human diseases <ul><li>Mutations in mitochondrial DNA (mtDNA) have been linked to diseases </li></ul><ul><ul><li>Bi-products of ATP formation can damage mtDNA </li></ul></ul><ul><ul><li>mtDNA mutations can be inherited </li></ul></ul><ul><ul><li>Example: Parkinsons or Alzheimer patients have more mtDNA mutations </li></ul></ul><ul><li>Figure 4.17 Mitochondria within a muscle cell </li></ul>
  38. 38. The Cytoskeleton Maintains Cell Shape and Assists Movement
  39. 39. 4.18 The cytoskeleton consists of filaments and microtubules <ul><li>Actin filaments - long, thin flexible fibers in bundled or mesh-like networks </li></ul><ul><ul><li>Play a structure role in the plasma membrane </li></ul></ul><ul><ul><li>Creates pseudopods amoebas to crawl </li></ul></ul><ul><li>Actin filaments interact with motor molecules , proteins that attach, detach, and reattach causing movement </li></ul>
  40. 40. Intermediate Filaments and Microtubules <ul><li>Intermediate filaments - size between actin filaments and microtubules </li></ul><ul><ul><li>Support nuclear envelope or plasma membrane and are in cell-to-cell junctions </li></ul></ul><ul><li>Microtubules – made of globular protein tubulin </li></ul><ul><ul><li>Radiate from centrosome and maintain cell shape and create tracks along which organelles move </li></ul></ul>
  41. 41. Figure 4.18 The three types of protein components of the cytoskeleton
  42. 42. 4.19 Cilia and flagella contain microtubules <ul><li>Cilia and flagella - whiplike structures of cells </li></ul><ul><ul><li>Unicellular protists use them to move </li></ul></ul><ul><ul><li>In our bodies cilia remove debris from respiratory tract and move eggs along oviduct </li></ul></ul><ul><li>Grow from basal bodies - same structure as centrioles , structures located outside the nucleus and used in mitosis </li></ul>
  43. 43. Figure 4.19 Flagellum
  44. 44. In Multicellular Organisms, Cells Join Together
  45. 45. 4.20 Modifications of cell surfaces influence their behavior <ul><li>Plants have a primary cell wall of cellulose microfibrils and a middle lamella of pectin </li></ul><ul><ul><li>Channels, plasmodesma, connect adjacent cells allowing water and solutes through </li></ul></ul><ul><li>Animals cells have junctions between plasma membranes </li></ul><ul><ul><li>Anchoring junctions prevent leakage </li></ul></ul><ul><ul><li>Tight junctions seal in digestive justices </li></ul></ul><ul><ul><li>Gap junctions allow cells to communicate </li></ul></ul>
  46. 46. Figure 4.20A Plant cells are joined by plasmodesmata
  47. 47. Figure 4.20B Animal cells are joined by three different types of junctions
  48. 48. Connecting the Concepts: Chapter 4 <ul><li>Eukaryotic cells contain several types of organelles. </li></ul><ul><li>But not all eukaryotic cells contain every type of organelle. Cells have many specializations of structure for their particular functions. </li></ul><ul><ul><li>Red blood cells lack a nucleus allowing more room for molecules of hemoglobin, the molecule that transports oxygen in the blood </li></ul></ul><ul><ul><li>Muscle cells are tubular and specialized to contract </li></ul></ul><ul><ul><li>Nerve cells have very long extensions that facilitate the transmission of impulses </li></ul></ul>