2. Chapter 3 Cell Structure and Function

3. 7-1 Early microscopes  1665 Robert Hooke discovered cells while observing slices of cork  Anton van Leewenhoek used a series of lenses to observe water organisms  1838 Matthias Schleiden found all plants made of cells  1839 Theodor Schwann found all animals made of cells.  1855 Rudolf Virchow found all cells come from cells

4. HookeLeeuwenhoek

5. Cell Theory  All living things are composed of cells.  All cells come from preexisting cells.  Cells are the basic unit of structure and function.

6. Schleiden/Schwann/Virchow

7. Cell types  Prokaryotes-no nucleus No membrane-bound structures Genetic material is not separated  Eukaryotes-true nucleus Membrane-bound organelles Genetic material separated from rest of cell

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10. 7-2 Organelles  Small specialized organ-like structures  Individual functions  Located in the cytoplasm (area outside the nucleus)

11. Nucleus  Contains the DNA Form of chromatin (string-like) Form of chromosomes for cell division  Instructions for protein synthesis  Surrounded by a nuclear envelope 2 layers Contains pores for movement of materials

12. Nucleolus  Located within the nucleus  Assembles ribosomes

13. Nucleus

14. Ribosomes  Small particles of RNA and protein  Found in cytoplasm  Produce proteins

15. Endoplasmic reticulum  Internal membrane system  Site of lipid and protein synthesis  Two types Rough ER – has ribosomes; makes protein Smooth ER – no ribosomes; makes lipids

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17. Golgi Apparatus  Discovered by Camillo Golgi  Receives, modifies, sorts, and packages lipids and proteins from ER  Sends these packages to be stored  Sends some out of the cell

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19. Lysosomes  Organelles filled with enzymes  Digests, lipids, carbohydrates, proteins, worn out cell parts

21. Vacuoles  Organelles used for storage  Store water, Salts Proteins carbohydrates

23. Mitochondria  Convert chemical energy (sugars) into useable energy (ATP)  Have 2 membranes  Outer membrane surrounds the organelle  Inner membrane is folded to increase surface area and increase ATP production

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25. Chloroplasts  Capture solar energy and convert it to chemical energy (sugar)  Surrounded by 2 membranes  Inner membrane contains the chlorophyll

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27. Organelle DNA  Chloroplasts and mitochondria contain their own DNA  May be descendants of ancient prokaryotes

28. Cytoskeleton  Network of protein filaments (microtubules and microfilaments)  Help maintain cell shape  Involved in cellular movement

29. centrioles  Found near the nucleus  Only in animal cells  Help organize cell division

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32. 7-3 Cell boundaries  Boundaries separate the cell from its external environment  Plasma membrane  Cell wall

33. Plasma membrane  Regulates what enters and leaves the cell  Provides protection and support  Made of a lipid bilayer (2 layers of lipids)  Fluid mosaic model (lipid molecules can exchange places)  Cholesterol holds membrane together  Carbohydrates are recognition markers

34. Summary Section 2 – pages 175-178 Structure of the Plasma Membrane The plasma membrane is composed of two layers of phospholipids back- to-back. Phospholipids are lipids with a phosphate attached to them.

35. Summary Section 2 – pages 175-178 The lipids in a plasma membrane have a glycerol backbone, two fatty acid chains, and a phosphate group. Glycerol Backbone Two Fatty Acid Chains Phosphate Group

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37. Cell wall  Found in plants, bacteria, fungi, some protists  Provides support and protection  Found outside the membrane  Made mostly of cellulose

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39. Concentration  Mass of a solute in a given volume of solution  Concentration plays a major role in diffusion

40. Diffusion  In solution, particles move constantly  Particles tend to move to areas where they are less concentrated (process called DIFFUSION)  When concentration of solute is the same throughout a system it is called (EQUILIBRIUM)  Does NOT require energy, just a concentration gradient

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42. Summary Section 2 – pages 152-156 The results of diffusion When a cell is in dynamic equilibrium with its environment, materials move into and out of the cell at equal rates. As a result, there is no net change in concentration inside or outside the cell. Material moving out of cell equals material moving into cell

43. Osmosis  Diffusion of water from an area of high concentration to an area of low concentration (with the gradient)  Movement of water through selectively permeable membranes  When equilibrium is reached, osmosis continues but there is no NET movement (or change in concentration)

44. Section 8.1 Summary – pages 195 - 200  Unequal distribution of particles, called a concentration gradient, is one factor that controls osmosis. What controls osmosis? Before Osmosis After Osmosis Water molecule Sugar molecule Selectively permeable membrane

45. Osmotic solutions  Isotonic – equal amounts of solute and water on both sides of the membrane  Hypertonic – having more solute and less water (cell will shrink)  Hypotonic – having more water and less solute (cell will swell and/or burst)

46. Section 8.1 Summary – pages 195 - 200 Cells in an isotonic solution  In an isotonic solution, water molecules move into and out of the cell at the same rate, and cells retain their normal shape. H2OH2O H2OH2O Water Molecule Dissolved Molecule

47. Section 8.1 Summary – pages 195 - 200 Cells in a hypotonic solution  In a hypotonic solution, water enters a cell by osmosis, causing the cell to swell. H2OH2O H2OH2O Water Molecule Dissolved Molecule

48. Section 8.1 Summary – pages 195 - 200 Cells in a hypotonic solution  Plant cells swell beyond their normal size as pressure increases.

49. Section 8.1 Summary – pages 195 - 200 Cells in a hypertonic solution  In a hypertonic solution, water leaves a cell by osmosis, causing the cell to shrink. H2OH2O H2OH2O Water Molecule Dissolved Molecule

50. Section 8.1 Summary – pages 195 - 200 Cells in a hypertonic solution  Plant cells lose pressure as the plasma membrane shrinks away from the cell wall.

51. Osmotic pressure  Pressure exerted by water on the hypertonic side of a membrane

52. Facilitated diffusion  Large molecules or charged molecules cannot diffuse directly through the lipid bilayer  Protein channels must open to allow them to pass from one side of the membrane to the other  Energy is NOT required  Occurs with the gradient

53. Section 8.1 Summary – pages 195 - 200 Passive Transport by proteins  Passive transport of materials across the membrane using transport proteins is called facilitated diffusion. Plasma membrane Channel proteins Concentration gradient

54. Active Transport  Movement of particles against a gradient  Creating larger solute difference across the membrane  Requires energy  Membrane proteins “pump” charged ions in specific directions

55. Section 8.1 Summary – pages 195 - 200 Active Transport  Movement of materials through a membrane against a concentration gradient is called active transport and requires energy from the cell. Plasma membrane Concentration gradient Carrier proteins Cellular energy Step 1Step 2

56. Section 8.1 Summary – pages 195 - 200 How active transport occurs  In active transport, a transport protein called a carrier protein first binds with a particle of the substance to be transported. Plasma membrane Concentration gradient Carrier proteins Cellular energy Step 1Step 2

57. Section 8.1 Summary – pages 195 - 200 How active transport occurs  Each type of carrier protein has a shape that fits a specific molecule or ion. Plasma membrane Concentration gradient Carrier proteins Cellular energy Step 1Step 2

58. Section 8.1 Summary – pages 195 - 200 How active transport occurs  When the proper molecule binds with the protein, chemical energy allows the cell to change the shape of the carrier protein so that the particle to be moved is released on the other side of the membrane. Step 1Step 2 Carrier proteins Cellular energy Plasma membrane Concentration gradient

59. Section 8.1 Summary – pages 195 - 200 How active transport occurs  Once the particle is released, the protein’s original shape is restored. Step 1Step 2 Carrier proteins Cellular energy Plasma membrane Concentration gradient  Active transport allows particle movement into or out of a cell against a concentration gradient.

60. Endocytosis  Taking materials into the cell by infoldings of the plasma membrane  Phagocytosis Folding large particles into a pocket of the membrane  Pintocytosis Folding molecules of liquids into pockets of the membrane

62. Exocytosis  Vacuole (containing materials) membrane fuses with the plasma membrane to release substances outside the cell