2. Cell Structure and Function

3. Cells Smallest living unit (plants and animals are composed of cells) Most are microscopic

4. Discovery of Cells Robert Hooke (mid-1600s) –Observed sliver of cork –Saw “row of empty boxes” –Coined the term cell

5. Cell theory (1839)Theodor Schwann & Matthias Schleiden “ all living things are made of cells” (50 yrs. Later) Louis Pasteur “all cells come from cells”

6. Principles of Cell Theory All living things are made of cells The smallest living unit of structure and function of all organisms is the cell Cells carry out the functions needed to support life. All cells arise from preexisting cells (this principle discarded the idea of spontaneous generation)

7. Why study cells? Cells  Tissues  Organs  Bodies –bodies are made up of cells –cells do all the work of life!

8. The Work of Life What jobs do cells have to do for an organism to live… –“breathe” gas exchange: O 2 in vs. CO 2 out –eat take in & digest food –make energy ATP –build molecules proteins, carbohydrates, fats, nucleic acids –remove wastes –control internal conditions homeostasis –respond to external environment –build more cells growth, repair, reproduction & development ATP

9. Cells provide structure and form to the body. They appear in a variety of shapes; round, concave, rectangular, tapered, spherical, and other. Cell shape seems to be related to specialized function.

10. Cell Size (Varies)

11. Cells are: Unit of Function: Each cell is a living unit. A cell performs many metabolic functions to sustain life. Each cell is a biochemical factory using food molecules for energy; repair of tissues, growth and ultimately reproduction.

12. Unit of Growth: Each living organism begins as a single cell. Some organisms such as a protist, remain unicellular. For a multicellular organism, as the number of cells increases in the body of a plant or animal, so too does its size.

13. Unit of heredity: New cells only arise from preexisting cells. A cell grows to optimum size and then divides, producing either two cells identical to itself OR four cells not identical. Cells carry hereditary information from one generation to the next. This information is coded in molecules of DNA (deoxyribonucleic acid).

14. Characteristics of All Cells Have a surrounding membrane Cytoplasm – cell contents in thick fluid Organelles – structures for cell function Control center with DNA

15. Cell Types Prokaryotic Eukaryotic

16. Two Types of Cells Prokaryotes First cells to evolve No nucleus Hereditary info is contained within cytoplasm Ex. Bacteria Eukaryotes Evolved from Prokaryotes Have a nucleus Hereditary Info is contained within the nucleus Ex. Plants, Animals, Fungi

17. Prokaryotic Cells First cell type on earth Cell type of Bacteria and Archaea

18. Prokaryotic Cells No membrane bound nucleus Nucleoid = region of DNA concentration Organelles not bound by membranes

19. Bacterium Shapes

20. Eukaryotic Cells Nucleus bound by membrane Include fungi, protists, plant, and animal cells Possess many organelles Protozoan

21. Representative Animal Cell

22. Representative Plant Cell

23. Organelles Cellular machinery

24. Cell Walls Found in plants, fungi, & many protists Surrounds plasma membrane Made of cellulose Is rigid Provides support and protection for the cell

25. Cell Wall Differences Plants – mostly cellulose Fungi – contain chitin

26. Cell membrane Surrounds all cells In a plant cell, it lies beneath the cell wall – In animal cells, it is the outer boundary (made of cholesterol) Lipid bilayer with embedded proteins Provides cell with – Protection Isolates the cell’s contents from external environment Regulates the flow of materials into and out of the cell (i.e. selectively permeable ) Allows interaction among cells Support

27. Cytoplasm Viscous fluid containing organelles components of cytoplasm –Interconnected filaments & fibers –Fluid = cytosol Found in both plant and animal cells Located beneath cell membrane Supports and protects cell organelles

28. Organelles Functional components within cytoplasm

29. Nucleus Function –control center of cell –protects DNA instructions for building proteins Structure –nuclear membrane –nucleolus ribosome factory –chromosomes DNA

30. Hereditary material Chromosomes

31. Nucleic Acid Deoxyribonucleic acid (DNA) has two functions: DNA controls protein synthesis in the cell DNA is replicated and passed on to progeny cells during reproduction

32. Nucleolus Most cells have 2 or more Directs synthesis of RNA Forms ribosomes

33. Endoplasmic Reticulum Helps move substances within cells Network of interconnected tubes Two types –Rough endoplasmic reticulum –Smooth endoplasmic reticulum

35. Rough Endoplasmic Reticulum Ribosomes attached to surface –Manufacture proteins –Not all ribosomes attached to rough ER

36. Smooth Endoplasmic Reticulum No attached ribosomes Has enzymes that help build molecules –Carbohydrates –Lipids

38. Endo-membrane System

39. transport vesicles vesicles carrying proteins Golgi Apparatus Function –finishes, sorts, labels & ships proteins like UPS headquarters –shipping & receiving department –ships proteins in vesicles “UPS trucks” Structure –membrane sacs

41. Lysosomes Found only in animal cells Contain digestive enzymes Functions –Aid in cell renewal –Break down old cell parts –Digests invaders

42. Lysosome

43. Peroxisome Similar to lysosome Membrane-bound vesicle that contains enzymes Enzymes are used to breakdown toxic substances to hydrogen peroxide Hydrogen peroxide is broken down by catalase to produce water and oxygen

45. Vacuoles Membrane bound storage sacs More common in plants than animals Contents –Water –Food –wastes

46. Mitochondria Have their own DNA Bound by double membrane Has inner foldings (Cristae) that increase the internal surface area

47. Mitochondria Break down fuel molecules ( cellular respiration) –Glucose –Fatty acids Release energy –ATP

48. Mitochondria Function –make ATP energy from cellular respiration sugar + O 2  ATP fuels the work of life in both animal & plant cells ATP

49. Plants make energy two ways! Mitochondria –make energy from sugar + O 2 cellular respiration sugar + O 2  ATP Chloroplasts –make energy + sugar from sunlight photosynthesis sunlight + CO 2  ATP & sugar –ATP = active energy –sugar = stored energy »build leaves & roots & fruit out of the sugars ATP sugar ATP

50. Chloroplasts Solar energy capturing organelle

51. Photosynthesis Takes place in the chloroplast Makes cellular food – glucose

52. Mitochondria are in both cells!! animal cells plant cells mitochondria chloroplast

53. Cells need workers = proteins! Making proteins –to run daily life & growth, the cell must… read genes (DNA) build proteins –structural proteins (muscle fibers, hair, skin, claws) –enzymes (speed up chemical reactions) –signals (hormones) & receptors –organelles that do this work… nucleus ribosomes endoplasmic reticulum (ER) Golgi apparatus

54. DNA RNA ribosomes endoplasmic reticulum vesicle Golgi apparatus vesicle protein on its way! protein finished protein Making Proteins TO: nucleus

55. Cells need to make more cells! Making more cells –to replace, repair & grow, the cell must… copy their DNA make extra organelles divide the new DNA & new organelles between 2 new “daughter” cells –organelles that do this work… nucleus centrioles

56. Centrioles Function –help coordinate cell division only in animal cells Structure –one pair in each cell

57. Cell Summary Cells have 3 main jobs –make energy need food + O 2 cellular respiration & photosynthesis need to remove wastes –make proteins need instructions from DNA need to chain together amino acids & “finish” & “ship” the protein –make more cells need to copy DNA & divide it up to daughter cells Our organelles do all those jobs!

58. Plasma Membrane Contains cell contents Double layer of phospholipids & proteins

59. Phospholipids Polar –Hydrophylic head –Hydrophobic tail Interacts with water

60. Movement Across the Plasma Membrane A few molecules move freely –Water, Carbon dioxide, Ammonia, Oxygen Carrier proteins transport some molecules –Proteins embedded in lipid bilayer –Fluid mosaic model – describes fluid nature of a lipid bilayer with proteins

62. Molecule Movement & Cells Passive Transport Active Transport Endocytosis ( phagocytosis & pinocytosis) Exocytosis

63. Passive Transport No energy required Move due to gradient –differences in concentration, pressure, charge Move to equalize gradient –High moves toward low

64. Types of Passive Transport 1. Diffusion 2. Osmosis 3. Facilitated diffusion

65. Diffusion Molecules move to equalize concentration

66. Osmosis Special form of diffusion Fluid flows from lower solute concentration Often involves movement of water –Into cell –Out of cell

67. Solution Differences & Cells solvent + solute = solution Hypotonic –Solutes in cell more than outside –Outside solvent will flow into cell Isotonic –Solutes equal inside & out of cell Hypertonic –Solutes greater outside cell –Fluid will flow out of cell

69. Facilitated Diffusion Differentially permeable membrane Channels (are specific) help molecule or ions enter or leave the cell Channels usually are transport proteins (aquaporins facilitate the movement of water) No energy is used

70. Process of Facilitated Transport Protein binds with molecule Shape of protein changes Molecule moves across membrane

71. Active Transport Molecular movement Requires energy (against gradient) Example is sodium-potassium pump

72. Endocytosis Movement of large material –Particles –Organisms –Large molecules Movement is into cells Types of endocytosis – bulk-phase (nonspecific) – receptor-mediated (specific)

73. Process of Endocytosis Plasma membrane surrounds material Edges of membrane meet Membranes fuse to form vesicle

74. Forms of Endocytosis Phagocytosis – cell eating Pinocytosis – cell drinking

75. Exocytosis Reverse of endocytosis Cell discharges material

76. Exocytosis Vesicle moves to cell surface Membrane of vesicle fuses Materials expelled

77. Membrane Proteins 1. Channels or transporters –Move molecules in one direction 2. Receptors –Recognize certain chemicals

78. Membrane Proteins 3. Glycoproteins –Identify cell type 4. Enzymes –Catalyze production of substances

79. Review of Eukaryotic Cells