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Science 10

Living Systems. Science 10. C1.0 Imaging The Cell. C 2.0 Cell Structures and Functions. C3.0 Plants as Multicellular Organisms. The Cell. 1.1 Early Microscope Technology. 1.2 The Cell Theory. 1.3 Imaging Technology. 1.4 Cell Research. Early Microscope Technology.

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Science 10

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  1. Living Systems Science 10 C1.0 Imaging The Cell C 2.0 Cell Structures and Functions C3.0 Plants as Multicellular Organisms

  2. The Cell 1.1 Early Microscope Technology 1.2 The Cell Theory 1.3 Imaging Technology 1.4 Cell Research

  3. Early Microscope Technology • The invention of the microscope allowed scientists to study the building blocks of living things • Two convex lenses made the first compound microscope • Robert Hooke combined three lenses to make a more powerful microscope • Anton van Leeuwenhoek further refined the microscope

  4. Cell Theory • Louis Pasteur refuted the theory of spontaneous generation using the scientific method (one manipulated variable, one responding variable, many controlled variables) • Through careful observation Theodor Schwann and Matthias Schleiden proposed the cell theory to explain the origin of life

  5. Cell Theory • The cell theory states that: • All living things are made of cells and the materials produced by cells • All life functions take place in cells making them the smallest unit of life • All cells are produced from pre-existing cells through the process of cell division

  6. Imaging Technology • Viewing cells under a microscope can be enhanced by: • Staining • Increasing resolution • Contrast and Fluorescence • Confocal technology • Electron microscopy (transmission versus scanning)

  7. Cell Research • New technologies have led to breakthroughs in: • Gene Mapping: determining the DNA sequence of a species • Cell Communication: cells interact with each other using molecules that act as chemical messengers • 3D Molecular Structure: visualizing molecules as they really exist

  8. Cell Research • Green Fluorescent Protein Technology: comparing healthy cells to diseased cells to diagnose illness

  9. Cell Structures and Functions 2.1 The Cell as an Open System 2.2 The Cell Membrane 2.3 Applications of Cellular Transport 2.4 Cell Size Limitations

  10. The Cell as an Open System • All cells are either prokaryotic or eukaryotic

  11. The Cell as an Open System • Two types of eukaryotic cells are plant and animal cells • Plant and animal cells have cellular structures called organelles • Differences between plant and animal cells include: • Plant cells have a cell wall; animal cells do not • Plant cells have chloroplasts; animal cells do not

  12. The Cell as an Open System • Plant cells have one large central vacuolethat stores water; animal cells have several small vacuoles that store water, nutrients or wastes • Animal cells have centrioles, plant cells do not

  13. The Cell Membrane • The cell membrane is a fluid mosaic • The membrane consists of a phospholipid bilayer with proteins interspersed • The proteins may act as channels, receptors or antigens

  14. The Cell Membrane • The cell membrane allows for particles to move into and out of the cell • Passive transport mechanisms involve no energy expense by the cell and include: • Diffusion: particles move from where they are more concentrated to where they are less concentrated (ie. down the concentration gradient) • Osmosis: Water moves down the concentration gradient

  15. The Cell Membrane • Facilitated Diffusion: Large particles move down the concentration gradient through channels • Active transport mechanisms move particles against the concentration gradient using cellular energy • Ion Pump: moves ions across the cell membrane using specialized proteins • Endocytosis: moves large particles into the cell by enveloping them in the cell membrane • Exocytosis: moves large particles out of the cell by expelling them from the cell membrane

  16. Applications of Cellular Transport • Studying the cell membrane has led to better understanding and treatment of disease • A recognition protein is a protein embedded in a cell membrane that allows a cell to be recognized by other cells • A receptor protein is a protein embedded in the cell membrane that bind to specific molecules outside the cell

  17. Applications of Cellular Transport • Some viruses attach to receptor proteins (example: HIV) • Cancer cells can be identified due to recognition proteins • A liposome is a synthetic membrane and can deliver medications to cells • Hormones are transported through channel proteins (example: insulin)

  18. Applications of Cellular Transport • Dialysis uses diffusion to treat kidney disease • Reverse osmosis is used to purify water

  19. Cell Size Limitations • The ratio of surface area to volume limits the size of cells • The greater the surface area to volume ratio the more efficient cellular transport can be • Small cells have a high surface area to volume ratio • Large cells have a low surface area to volume ratio

  20. Plants 3.1 Cells, Tissues and Systems 3.2 The Leaf and Photosynthesis 3.3 Gas Exchange in Plants 3.4 Transport in Plants 3.5 Control Systems

  21. Cells, Tissues and Systems • The advantages of multicellular organisms include: • Division of Labour: many specialized cells can be more efficient one generalized cell • Size: Many small cells have sufficient surface area to support larger sized organisms • Interdependence of Cells: if one cell dies a multicellular organism still survives

  22. Cells, Tissues and Systems • Cells of multicellular organisms can be organized into: • Tissue: a group of similar cells contributing to the same function • Organ: a group of related tissues contributing to the same function • Organ System: a group of related organs contributing to the same function

  23. Cells, Tissues and Systems • Plants have two organ systems • Shoot System: above ground structures including the stem, leaves, buds, flowers fruits and tubers • Root System: underground structures including roots and buttresses • Plants grow from the meristems of the roots and shoots

  24. Cells, Tissues and Systems • Plant tissues include: • Epidermis: the outer layer of cells that covers all herbaceous plants that in leaves and roots is covered in a cuticle • Ground Tissue: the majority of plant cells that provide support, storage and strength • Vascular Tissue: cells that transport nutrient, water and sap (includes xylem and phloem)

  25. Cells, Tissues and Systems • Root Hairs: extensions of epidermal cells in roots that increase surface area for absorption of water and minerals • Guard Cells: create pores called stomata for gas exchange

  26. The Leaf and Photosynthesis • A leaf has different tissues to help the plant do photosynthesis efficiently • Photosynthesis is carried out inside chloroplasts • Chloroplasts contain a molecule called chlorophyll • Chloroplasts move within a plant cell due to cytoplasmic streaming

  27. The Leaf and Photosynthesis • Plant cells carry out both cellular respiration and photosynthesis • The rate of net production of a plant can be determined by measuring the amount of oxygen gas produced or the amount of carbon dioxide consumed

  28. Gas Exchange in Plants • Stomata allow for oxygen to be excreted and carbon dioxide to be ingested by a leaf • Stomata remain closed during the day when the rate of transpiration is high and open at night • Guard cells open and close the stomata

  29. Gas Exchange in Plants • Once inside the leaf, carbon dioxide can diffuse around the mesophyll cell (palisade and spongy) • Vascular tissue bring water into the leaf for photosynthesis • Gas exchange occurs on stems and roots through lenticels

  30. Transport in Plants • Water moves through plants due to its properties of adhesion and cohesion • Water is polar so it has relatively strong intermolecular forces • Root pressure causes water to flow up the plant and accumulate in the leaves and stems at night • Transpiration is the movement of water from the roots, through the stem and out the stomata of the leaves of a plant

  31. Transport in Plants • Transpiration pull is the effect of water molecules evaporating off of leaves and pulling adjacent water molecules along • A plant cell in a hypertonic environment will exhibit plasmolysis • A plant cell in a hypotonic environment will exhibit turgor • Sugars move down the plant from the source (leaves) to the sink (root or fruit)

  32. Control Systems • Plants can respond to stimuli but less obviously than animals • Plants respond to light using phototropism • Phototropism allows plant shoots to grow toward light using elongation due to auxin • Plants respond to direction using gravitropism • Gravitropism involves the plant sensing the location of starch granules inside cells

  33. Control Systems • Tropisms can be positive or negative • Plants exhibit tropisms in response to temperature, water, touch and others

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