Topic

• Cell theory


  A theory that describes the basic requirements of how we perceive life
• Cell theory


  • All living things are composed of cells
  • Cells are the smallest unit of life
  • Cells only arise from pre-existing cells
• There are exceptions to the main conventions of cell theory
• Exceptions to cell theory

  • Cells that make up striated muscle fibers
  • Giant algae
• Functions of life


  • Reproduction
  • Metabolism
  • Responsiveness or sensitivity
  • Homeostasis
  • Growth
  • Excretion
  • Nutrition
• Cells are constantly growing, but we don't grow to be as tall as a skyscraper or as wide as an island
• Surface area to volume ratio

  As cells get larger, the surface area grows at a slower rate than the volume, eventually leading to cell death if the cell becomes too large
• Cells undergo cell division to maintain a stable surface area to volume ratio
• Magnification


  Magnification (M) = Image size / Actual size
• Multicellular organisms have cells that work together to create new emergent properties
• Cell differentiation


  The process where different genes are turned on or expressed within a cell's DNA, signaling for that cell to become a specific type of cell (e.g. nerve cell, muscle cell, etc.)
• Stem cells


  Precursor cells that do not have a specific function and can turn into multiple types of specialized cells
• Stem cells can be used for therapy, but there are ethical debates around where to obtain the best stem cells