Genetics - 01 A closer look at cells


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A closer look at cells and their organelles for Year 10 students at Saint Ignatius College Geelong

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  • Robert Hooke first discovered the cell in 1665 (cork cells), but not till 19th Century when Schann & Schleiden (1839) & then Virchow (1858) suggested that cells were the basic unit of life. Before this spontaneous generation believed.
  • Transmission EM = electron beam travels through the sectionScanning EM = electron beam bounces off surface (that has been fixed by coating with gold)  higher resolution
  • Genetics - 01 A closer look at cells

    1. 1. GENETICS. 01. A closer look at cells. Ian Anderson Saint Ignatius College Geelong
    2. 2. KEY KNOWLEDGE & SKILLS  Outline the cell theory.  Compare prokaryotic and eukaryotic cells at light and electron microscope levels.  List the specialised parts of cells and describe their roles.  State the main differences between plant and animal cells.
    3. 3. CELL THEORY.  All living things are made of cells.  All cells come from pre-existing cells.  Cells are the basic building blocks of all life. Source:
    4. 4.  Holds true for all living things.  From simple, unicellular organisms. Cell theory. Source: Paramecium.htm
    5. 5.  To the more complex multicellular organisms. Cell theory. Source: ber_2007.jpg
    6. 6. CELL THEORY. To understand life you need to understand how cells work.  Even though cells are specialised for many different purposes, they share some common features.  They all have a similar cell structure.  They all perform similar basic functions.  They are all made up of ‘the molecules of life’.
    7. 7. LOOKING AT CELLS. Light microscopes  Magnify up to 1000-2000 times. Electron microscopes.  Magnify up to 2 million times.  Transmission v scanning electron microscopy Synchrotron.  Magnification to molecular level!
    8. 8. CELL STRUCTURE. Cells can be classified into two major types based on their level of cell structure.  Prokaryotic cells.  Eukaryotic cells.
    9. 9. PROKARYOTIC CELLS. (pro = before; karyotic = a nucleus).  Small, primitive cells.  Lack membrane-bound organelles.  Have a single circular DNA chromosome.  In addition, can also have several small circles of DNA called plasmids.  Have a cell wall.  e.g. bacteria & cyanobacteria. Source: Mechanism-Behind-BacterialProkaryotic-Motility
    10. 10. EUKARYOTIC CELLS. (eu= with; karyotic = a nucleus).  More advanced & usually larger than prokaryotic cells.  Contain membrane-bound organelles.  Distinct nucleus and other organelles.  e.g. plants, animals, fungi, protista. Source:
    11. 11. EUKARYOTE ORGANELLES. Organelle Function Plasma membrane Controls entry of substances into and out of the cell. Nucleus Contains genetic material and controls cellular activities. Mitochondrion Involved in the energy transformations that release energy for the cell. Endoplasmic reticulum A network of intracellular membranes forming channels through which proteins are moved. Golgi apparatus Packages the protein into vesicles for transport across the plasma membrane and out of the cell. Ribosomes Sites of protein synthesis. [Also found in prokaryotes].
    12. 12. EUKARYOTE ORGANELLES. Organelle Function Lysosome Membrane bound vesicles containing digestive enzymes. Vacuole Membrane bound organelle. In plants – usually large and help maintain water balance within the cell and provide turgidity. In animals – usually smaller and involved in intracellular digestion or water balance. Cilia & flagellum Involved with movement. Chloroplasts Site of photosynthesis. Centrioles Points of attachment for the spindle fibres during mitosis.
    13. 13. EUKARYOTE ORGANELLES. Electron micrograph of a liver cell (x9000) Source: Walpole et al. (2011)
    14. 14. PLANT V ANIMAL CELLS. Source:
    15. 15. PLANT V ANIMAL CELLS.  All plant cells contain a cell wall outside the plasma membrane. Made of cellulose. Provides structural support and is permeable to most substances. Animal cells do not have a cell wall.  Chloroplasts are often found in plants, but never in animal cells.  Vacuoles can be found in both plant and animal cells, In plant cells, often large and play key role in maintaining osmotic balance. In animal cells, never large.  Centrioles are only found in animal cells.
    16. 16. THE INNER LIFE OF A CELL. Source:
    17. 17.