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  1. 1. Cells<br />IS3<br />
  2. 2. Life<br />Possible origins:<br />Extraterrestrial<br />Supernatural (religious)<br />Chemical Evolution (inorganic -> organic -> cells)<br />Requirements for life:<br />C, H, O, N, P, S<br />Sunlight/chemical energy<br />UV radiation protection<br />Water<br />“Found: first amino acid on a comet” <br />17 August 2009 by Maggie McKee<br /><br />
  3. 3. Cell Discovery<br />Linked to microscope development<br />1595 – Hans Janssen + son Zacharias (Dutch): credited with microscope invention<br />Two main types: light and electron<br />
  4. 4. Light Microscope<br />Light passes through an object and 2 or more lenses<br />Possible to see living cells – not a lot of detail<br />Advantages: <br />Object: can be living<br />Staining not required<br />Real colors visible<br />Easy to work with<br />But low resolution: up to 200 nm +<br />low magnification: up to 2000X<br />
  5. 5. Electron Microscope<br />Two types<br />Scanning Electron (SEM)<br />uses electron beams that bounce off the specimen<br />Transmission Electron (TEM)<br />Used electron beams that pass through specimen<br />Advantages: <br />more detail / higher resolution (0.2nm) / magnification: close to 1 million X<br />But specimen must be dead + colors aren’t real.<br />
  6. 6. Transmission Microscope (guess what these structures are...)<br />Scanning Microscope<br />
  7. 7. Timeline<br />Anton van Leeuwenhoek (Dutch – 1632-1723)<br />Improved simple microscope (single lens – magnification up to 270 X)<br />First to see living cell (red blood cells, sperm cells, single celled organisms)<br />
  8. 8. Timeline<br />Robert Hooke (English – 1635-1703)<br />Looked at a piece of cork – first to use the term "cell“<br />Improved microscope: compound (2 lenses)<br />1800 – scientists knew cells had a cell membrane, a nucleus, cytoplasm and cell wall<br />
  9. 9. Timeline<br />Mathias Schleiden – (German botanist – 1804-1881) <br />all plants are made of cells<br />Theodor Schwann (German zoologist – 1810-1882) <br />all animals are made of cells<br />Rudolf Virchow (German physician – 1821-1902)<br />concluded that all cells come from other cells<br />
  10. 10. Cell Theory<br />All organisms are made up of one or more cells.<br />Cells are the basic units of structure and function in all organisms.<br />All cells come from cells that already exist.<br />Exception:<br />Viruses are non-cellular structures of DNA or RNA that are surrounded by a protein coat<br />
  11. 11. Single-cell x Multicellular<br />Organisms can be made up of one cell (single-celled) or many cells (multicellular).<br />Single-celled organisms are the bottom of the food chain<br />There are more single-celled organisms than multicellular organisms in the world.<br />
  12. 12. Single Cell Organisms<br />One cell carries out all functions:<br />Metabolism: all chemical reactions happening at the same time<br />Response: sense environment<br />Homeostasis: regulate/balance reactions in the body according to the environment conditions<br />Growth: production of new organelles<br />Reproduction: division <br />Nutrition: release energy from food<br />Amoeba<br />Paramecium<br />
  13. 13. Multicellular Organisms<br />Interaction<br />Communication<br />Cells specialize: they differentiate because some genes are expressed and some are not (on/off) depending on the type of cell.<br />Neuron<br />Muscle cell<br />Skin cell<br />Stem cells = not specialized = ability to differentiate into specialized cells<br />
  14. 14. Trypanosoma<br />Diatoms<br />
  15. 15. Why are cells small?<br />Surface area to volume ratio limits cell size<br />Rate of heat production/waste/resource consumption – volume<br />Rate or exchange material/energy – surface area<br />As cell size increases, the surface area to volume ratio decreases<br />Metabolic rates increase faster than the surface area’s ability to exchange nutrients, hence a maximum size is reached.<br />Cell size, therefore, remains small<br />
  16. 16. Size of various cells and structures<br />Molecules: 1 nm<br />Membranes (on organelles): 10 nm<br />Viruses: 100 nm<br />Bacteria: 1 um<br />Organelles: up to 10 um<br />Most cells: up to 100 um<br />Measurements above in 2d, remember all structures have 3d shape.<br />
  17. 17. Cell Organization<br />Cells differ:<br />Size<br />Shape<br />
  18. 18. Types of Cells<br />Types: <br />Prokaryotic (no nucleus + naked DNA in cytoplasm + only ribosomes)<br />Example: Bacteria<br />Eukaryotic (with nucleus + organelles)<br />Example: Animals, Plants, Fungi, Protists<br />
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  21. 21. Cell Membrane<br />Outer boundary: phospholipid bilayer<br />Communication between cells<br />Selects what goes in and out (using energy – active transport or without using energy – passive transport)<br />Animal cells have cholesterol in the membrane<br />
  22. 22. Cell Organelles<br />Organelle - structure within a cell that has a specific function.<br />Endoplasmic Reticulum – membranes that move materials around in the cell (“transport system”)<br />Ribosomes – make proteins (“factories”)<br />Centrioles (animals only) – coordinate cell division<br />
  23. 23. Cell Organelles<br />Mitochondria – produce ATP (“power plant”)<br />Golgi apparatus – makes, packages and releases products inside/outside cell (“factories”)<br />
  24. 24. Cell Organelles<br />Lysosome (animal only) – contain digestive enzymes. Breaks down and recycles substance (“garbage company”)<br />Vacuoles – (mainly plants) store waste, food, pigments (“storage”) <br />
  25. 25. More parts...<br />Cytoplasm – gel-like mixture inside cell. Many chemicals are dissolved in it.<br />Nucleus - largest structure in the cytoplasm (“command center”)<br />Has a nuclear membrane (with pores – materials enter and leave the nucleus)<br />Contains chromosomes (made of DNA – deoxyribonucleic acid)<br />
  26. 26. Plant Cells<br />Cell wall – rigid structure that provides support/protection for the cell<br />Chloroplasts – contain chlorophyll – green pigment responsible for photosynthesis<br />
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  28. 28. Stem Cells<br />Unspecialized: pluripotent or multipotent<br />Self-renewing<br />Give rise to mature, specialized cells<br />Sources: <br />Embryonic – cells from human blastocysts<br />Fetal – cells from aborted fetuses<br />Umbilical cord stem cells – cells from the umbilical cord of newborns<br />Placenta derived stem cells – cells from the placenta and amniotic fluid of newborns<br />Adult – cells from adult tissue (bone marrow, fat...)<br />
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  30. 30. Example<br /> Adult stem cell found in bone marrow<br /> red blood cells, white cells, platelets<br />
  31. 31. Types of Stem Cells: <br />Totipotent – each cell can develop into a new individual (cells from early embryos – 1-3 days)<br /> Pluripotent – cells can form any cell type (over 200) – some cells of blastocyst (5 to 14 days)<br /> Multipotent – cells differentiated, but can form other tissues – fetal tissue, cord blood, adult stem cells<br /><br />
  32. 32. Importance<br />Use: <br /> Cancer therapy: + 400,000 – leukemia, lymphoma, breast cancer, multiple myeloma<br /> Bone marrow/immune regeneration: 2 million – autoimmune diseases, immunodeficiencies, solid organ transplants<br /> Tissue repair/regeneration: 18 million – heart and vascular problems, diabetes, liver disease, arthritis, neurodegenerative<br />Potential Therapeutic Applications: <br /> Cardiac – following heart damage<br /> Nervous system – stroke/spinal cord, Parkinson’s, Alzheimer’s <br /> Burns<br /> Diabetes<br /> Solid organ regeneration<br />
  33. 33. Issues<br />Embryo destruction: ethics/religion<br />Tissue rejection<br />Government funding<br />Uncontrolled cell division / misdirected growth<br /><br />