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Cell Theory

Red blood cells in a fibrin net. Neuron cell diagram. Cell Theory. Topic 2.1. Cell theory has three basic principals: All living things are made of cells Multicellular organisms have specialized cells to carry out various functions Are unicellular organisms ‘made of cells’?. Onion Cell.

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Cell Theory

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  1. Red blood cells in a fibrin net Neuron cell diagram. Cell Theory Topic 2.1

  2. Cell theory has three basic principals: • All living things are made of cells • Multicellular organisms have specialized cells to carry out various functions • Are unicellular organisms ‘made of cells’? Onion Cell http://faculty.ntcc.edu/mhearron/the_cell.htm Human muscle cell • Cells are the smallest units of life • Organelles carry out various metabolic functions in the cell • Cell components cannot survive alone • Cells come only from other cells • Cells multiply by division • Mitosis and meiosis in eukaryotes • Binary fission in prokaryotes • All cells descend from simpler common ancestors Frog embryo - cell division http://www.sciencephoto.com/media/314310/enlarge

  3. Evidence for cell theory: “All living things are made of cells” • Robert Hooke (1635 – 1703): • Pioneering optics enthusiast. • Responsible for coining the term “Cell” after looking at cork sections under a microscope • Antonie van Leewenhoek(1632 – 1723): • “Father of Microbiology” & Master lens maker. • Used lens to study quality of cloth in his factory. • Discovered ‘animalcules’ in water. Became known as the discoverer of cells. http://www.amillionlives.net/category/biography/scientist http://en.wikipedia.org/wiki/Antonie_van_Leeuwenhoek

  4. Hooke’s cork cells Click to start animation http://www.youtube.com/watch?v=Q2ezDdKyRUc

  5. Evidence for cell theory: “All living things are made of cells” • Through the 1700’s & 1800’s the idea of spontaneous generation persisted. • Louis Pasteur disproved the idea in 1864. • Preventing entry of airborne particles to a nutrient broth, he stopped the growth of culture. Leaving it open allowed microbes to grow. http://amoebamike.files.wordpress.com/2009/10/pasteurs-experiment.jpg

  6. Evidence for cell theory: “All living things are made of cells” • In studying chicken embryos Robert Remakdiscovered cell division under the microscope. Robert Remak http://originsofcelltheory.wordpress.com/

  7. All living organisms carry out the functions of life: Nutritionreproductionmovementexcretion growth growthresponse to stimulushomeostasis • Unicellular organisms, such as amoebae, are capable of all these functions. • Multicellular organisms: • Have specialized cells to carry out specific functions. • As a whole all functions are covered. • Viruses are not generally classified as “living”: • They cannot carry out all of the functions independently. • They must invade a host cell and use its apparatus to survive. http://www.microscopy-uk.org.uk/mag/indexmag.html?http://www.microscopy-uk.org.uk/mag/wimsmall/sundr.html http://www.youtube.com/watch?v=I3Jo7moaLdI

  8. Total magnification = Eye piece lens X objective lens. So the magnification here is: 10 X 10 = 100X

  9. Standard International (SI) units of measure

  10. Standard International (SI) units of measure

  11. Calculations in microscopy Use these calculations to find the magnifications or actual sizes of images. Convert all units to make them the same (where appropriate) Perform calculations Convert answers to appropriate SI units, using scientific notation where needed.

  12. http://www.cellsalive.com/howbig.htm

  13. Big cells vs. small cells What is the ratio of cell membrane per unit volume? 1 Volume 27 6 Surface area (SA) 54 6:1SA:Vol2:1 • The plasma membrane is responsible for import/export in the cell. • Metabolic reactions occur inside the membrane • A larger SA:Vol ratio means small cells can act more efficiently moving nutrients, etc. into the cell, and wastes, etc. out of the cell. This is because there is more unit of membrane for every unit of volume.

  14. How else is a large SA:Vol ratio a benefit? • Diffusion pathways are shorter, so more efficient. • Molecules do not have to travel so far to get in or out of a cell, so it takes less time and (if it is active transport) energy. • Concentration gradients are easier to generate which makes diffusion more difficult.

  15. Is a large SA:Vol ratio always a benefit? A large SA:Vol ration is not always an advantage: small, warm-blooded mammals lose heat very quickly due to their large SA:VOL ration. They eat constantly Desert plants would lose water quickly with flat leaves. So they adapt for this problem. http://tucsoncitizen.com/wryheat/2009/11/12/creatures-of-the-night-kangaroo-rat/ http://en.wikipedia.org/wiki/Saguaro

  16. So how do organisms maximize SA:Vol ration? • As organisms grow, cells divide. • Two small cells are more efficient than one large cell – remember why?? • This also allows for cell differentiation – specialized functions and more complex multicellular life. • Cells compartmentalize – they use membranes to carry out metabolic processes. In eukaryotes these are called organelles. • Organelles themselves, like mitochondria, are also make up of membranes- maximizing the surface are for reactions. http://www.answers.com/topic/mitochondrion

  17. So how do organisms maximize SA:Vol ratio? • Some organs (intestine) fold up to maximize SA:VOL ratio making absorption of food molecules more efficient. • Alveoli in the lungs are thin membranes that maximize the surface for gas exchange. http://www.3dscience.com/3D_Models/Human_Anatomy/Alveoli/Alveoli.php http://mycozynook.com/102RGCh20OH.htm

  18. Emergent Properties: When we break something complex into its component pieces, they each appear to be simple. Combined, they can perform a whole new function.

  19. Emergent Properties: • Multicellular organisms show emergent properties. • The whole organisms can achieve more than the individual cells that make them up. • Emergent properties are caused by organelle interaction allowing them to perform tasks.

  20. Stem cell retain the capacity to divide • Totipotent: can become any cell type • Pluripotent: can become any type except embryonic membrane • Multipotent: can become a number of different cell types. • Differentiation depends on the activation sequence of genes in a sequence, often triggered by environmental change. • Once a stem cell has differentiated, it can only make more stem cells or the differentiated cell type. http://www.csa.com/discoveryguides/stemcell/overview.php

  21. http://learn.genetics.utah.edu/content/tech/stemcells/scintro/http://learn.genetics.utah.edu/content/tech/stemcells/scintro/ • All cells in the body carry the same genes in heir nuclei. • What makes a cell different is which genes are expressed – turned on o turned off • This is triggered by changes and the environment around the cell.

  22. http://stemcells.nih.gov/info/scireport/chapter1.asp

  23. Stem Cell Transplants: treatment of lymphoma • Lymphomatreatment - bone marrow is destroyed in chemo- or radio-therapy • Before this aggressive treatment takes place, stem cells are harvested from the bone marrow and stored. http://www.lymphomation.org/bmt-auto.htm • Harvested cells can be used to replace the damaged bone marrow, producing healthy blood cells in the recovering patient. http://www.youtube.com/watch?v=6TnO474Zou0

  24. Therapeutic Cloning of Stem Cells: Therapeutic cloning involves the in-vito culturing of tissues using patient or donor stem cells. It can be used to replace tissues lost in disease, burned skin or even nerve cells. http://whyfiles.org/148clone_clash/index.html http://www.youtube.com/watch?v=XL72Dn3rJ_E

  25. Because embryonic stem cells are the most versatile, they have been at the center of research and controversy. http://cmbi.bjmu.edu.cn/cmbidata/stem/specific/specific01.htm

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