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Introduction to Cytology or Cell Biology

Introduction to Cytology or Cell Biology. How do we observe cells?. Light microscope Visible light passes through object Lens magnify image Electron microscope Scanning - surface of object Transmission - sees through objects 100,000 X to Millions magnification power.

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Introduction to Cytology or Cell Biology

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  1. Introduction toCytology or Cell Biology

  2. How do we observe cells? • Light microscope • Visible light passes through object • Lens magnify image • Electron microscope • Scanning - surface of object • Transmission - sees through objects • 100,000 X to Millions magnification power

  3. How do we know what happens in each part of the cell? • Radioisotopes are used to "trace" different chemical reactions through a cell. • Separate cellular structures with a blender • Centrifuge material and analyze each layer.

  4. People who were important in early cell discovery:

  5. Zacharias Jannsen (1590) • Helped invent the First compound microscope

  6. Marcello Malpighi (1661) • Malpighi observes capillaries

  7. Robert Hooke (1665) • Observed dead cork - called them “cells“ • Compound Microscope

  8. Anton Von Leeuwenhoek (1674) • - living cells in pond water; one celled organisms -- animalcules

  9. Robert Brown (1831) • identifies the nucleus of a cell

  10. Mattias Scleiden (1838) • stated that plants are made up of cells

  11. Theodor Schwann (1839) • stated that animals are made up of cells

  12. Rudolph Virchow (1858) • Studied the pathology of cells. (ability to cause disease) • All cells arise from preexisting cells. • New cells can only arise from other living cells by the process of cell division or reproduction

  13. Cell Theory • All living things are composed of cells • Cells are the fundamental building block of life • All cells come from pre-existing cells (life begets life)

  14. PROCESSES OF CELLS All life processes involve energy changes. 1. Nutrition - food is needed for energy and building materials. 2. Digestion - breaking down reactions of food into usable parts. 3. Absorption - water, food, ions and other materials 4. Biosynthesis - cells organize many organic substances for cell activity. 5. Respiration - cell energy is released when certain organic molecules are split - energy is used for cell activity.

  15. 6. Excretion - waste materials passed from cell to environment 7. Secretion - synthesized molecules which are passed out of a cell and which affect the activities of other cells (vitamins, hormones) 8. Reproduction - cells divide; unicellular - more organisms, multicellular - more cells. 9. Movement - motion of all types; cellular contractions, flowing substances within the cell 10. Egestion - elimination of insoluble compounds and nondigestible particles

  16. Eukaryotic cells – advanced cells • Have nucleus • Plasma membrane • Cytoplasm - everything between plasma membrane and nucleus • Organelles • Fluid • Cytoskeleton – threads of microtubules and microfilaments in cytoplasm

  17. Animal vs Plant Cell • Animal cells have unique structures • Centrioles • Lysosome • Flagellum 1. 2. 3. • Plant cells have unique structures • Large central vacuole • Cell wall 1. 2. • Chloroplasts 3.

  18. Cytoskeleton Fibres Mitochondrion Mitochondrion Chloroplast Vesicle Golgi Body Central Vacuole Smooth ER Plant Cell Rough sdfER Cell Wall Plasma Membrane Nucleolus Pore DNA Envelope Ribosomes

  19. Animal Cell Centriole

  20. Plasma Membrane OUTSIDE OF CELL Lipid Bilayer Sugar Chain Protein Marker Cholesterol Embedded Protein Proteins INSIDE OF CELL

  21. Cell Membrane Side Profile

  22. Different membranes • All have similar functions & structures • Plasma membrane separates inside of cell from outside of cell • Other membrane define organelles to form compartments of eukaryotic cells • Forms a selectively permeable layer • Lets some things in or out but not all • Like a window screen

  23. Nucleus

  24. Nucleus - Structures • Envelope • Double membrane • Pores to get messages in and out • Chromatin • DNA threads • Protein balls called histones - wrapping • Nucleolus - site of ribosome production

  25. Ribosomes

  26. Consists of 2 parts, which are made in nucleus • Make protein in the Cytoplasm • Produce proteins from ‘recipes’ in the nucleus copied into mRNA • Some (proteins) will remain in cytoplasm • Some will be exported out of cell • Some will attach to membranes in cell • Ribosomes are found on the endoplasmic reticulum and in the cytoplasm

  27. Endoplasmic Reticulum Rough ER Smooth ER

  28. Rough Endoplasmic Reticulum • Rough ER - attached to nucleus • Ribosomes stud surface • Produces • Membrane proteins - stay in cell • Secretory proteins - exported from cell

  29. RER makin’ Proteins!

  30. Smooth Endoplasmic Reticulum • No ribosomes, so not protein factories • Makes steroids, lipids • Liver cells have lots of smooth ER • Detoxify chemicals • Supply and demand • Increases tolerance to drug • So higher doses needed for same effect

  31. Golgi apparatus – the Post Office of the Cell

  32. Golgi apparatus – what it does • Refines, stores and marks molecules for shipment • Looks like stack of hollow pancakes • Products of ER arrive & leave via transport vesicles • Moving from one sac to the next • Molecules get modified • Labeled and / or stored • Called the cell “Post office” because it marks and directs products in the cell

  33. Lysosome

  34. Lysosome • Greek for breakdown body • Recylcer • Sac of strong digestive enzymes • Compartmentalized for safety • Can release to breakdown entire cell – “suicide sack” • Functions • Digest food vacuoles • Digest invading bacteria • Digest old organelles

  35. Lysosome

  36. Lysosomal diseases • Genetic disorders • ‘Recipe’ is messed up so protein doesn’t work • If recipe for lysosome enzyme • What should get broken down doesn’t • Ex. Tay Sachs • Lipids aren’t broken down • Build up occurs • Eventually causes death • Usually in before age 5

  37. Mitochondria

  38. Mitochondria • Site of cellular respiration • Conversion of food into energy (ATP) • ATP is what cells use to make things happen (drive chemical reactions) • Double membrane • Big bag stuffed in smaller bag • Folds of inner bag called cristae • Space inside inner bag called matrix • Also once free living bacteria • Efficiency - gasoline engines converts 25% of energy mitochondria converts 54% of energy

  39. contains some of its own DNA (amount varies within organisms) • believed to evolved from a primitive cell engulfing it and creating a symbiotic relationship • DNA in mitochondria obtained only from mother of organism.

  40. Plant Organelles Chloroplasts - in plants Chloroplast 1. chlorophyll is green chemical that releases electrons, working like a solar panel in sunlight 2. forms glucose 3. photosynthesis 6CO2 + 6H2 O ---> C6H12 O6 + 6O2

  41. Chloroplasts

  42. Structure of Chloroplast • Double membrane • Grana • Stack of thylakoids • Hollow disk • Where sunlight energy is captured and converted to chemical energy • Stroma • Thick fluid filling chloroplast • Contains some DNA • Once free-living bacteria

  43. Cytoskeleton

  44. Role of the Cytoskeleton Network of fibers • Give shape to cells • Allow movement of cell • Move organelles around • Made of microtubules and microfilaments

  45. Centrioles • Cell reproduction; goes to poles of cell during cell division and helps cell divide

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