1.1 Introduction to cells

Essential idea:  
The evolution of multicellular organisms allowed cell specialization and cell replacement.
Understandings: Nature of science:
  • According to the cell theory, living organisms are composed of cells.
  • Organisms consisting of only one cell carry out all functions of life in that cell.
  • Surface area to volume ratio is important in the limitation of cell size.
  • Multicellular organisms have properties that emerge from the interaction of their cellular components.
  • Specialized tissues can develop by cell differentiation in multicellular organisms.
  • Differentiation involves the expression of some genes and not others in a cell’s genome.
  • The capacity of stem cells to divide and differentiate along different pathways is necessary in embryonic development and also makes stem cells suitable for therapeutic uses.
  • Looking for trends and discrepancies—although most organisms conform to cell theory, there are exceptions. (3.1)
  • Ethical implications of research involving stem cells is growing in importance and raises ethical issues. (4.5)
  • Applications : Guidance:
  • Questioning the cell theory using atypical examples, including striated muscle, giant algae, and aseptate fungal hyphae.
  • Investigation of functions of life in Paramecium and one named photosynthetic unicellular organism.
  • Use of stem cells to treat Stargardt’s disease and one other named condition.
  • Ethics of the therapeutic use of stem cells from specially created embryos, from the umbilical cord blood of a new-born baby and from an adult’s own tissues.
  • Students are expected to be able to name and briefly explain these functions of life: nutrition, metabolism, growth, response, excretion, homeostasis and reproduction.
  • Chlorella or Scenedesmus are suitable photosynthetic unicells, but Euglena should be avoided as it can feed heterotrophically.
  • Scale bars are useful as a way of indicating actual sizes in drawings and micrographs.
  • Skill:
  • Use of a light microscope to investigate the structure of cells and tissues, with drawing of cells.
  • Calculation of the magnification of drawings and the actual size of structures and ultrastructures shown in drawings or micrographs. (Practical 1)
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    Topic 1 Cell Biology Copyright © by Alex Black. All Rights Reserved.

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