Introduction to Cells

Introduction to Cells

1. The Cell Theory

   • living organisms made of cells
   • first explored: 17th century
   • cells are the fundamental blocks of all living organisms
   • common features of cells
     • surrounded by membranes
     • contains genetic information
     • cells activities: chemical reactions catalysed by enzymes produced in cell
     • have own energy release sytems

2. Unicellular organisms

   • consisting of only one cell
   • carries out all life functions
     • Metabolism
     • Growth
     • Excretion
     • Homeostasis
     • Nutrition
     • Response
     • Reproduction
   • some move; some drift in air/water or stay fixed

3. Limitations on cell size

   • surface area to volume ratio
     • too small
       • surface absorption less
       • waste accumulates
       • overheating
   • metabolic rate of cell is proportional to volume
   • substance absorbption and waste excretion important
     • movement through plasma memberanes
     • surface area determines

4. multicellular organisms

   • have properties that emerge from cell interaction
     • emergent properties
     • whole is greater than sum of its parts
   • mass of cells fused together
   • cooperative groups

5. Cell differentiation in multicellular organisms

   • used to develop specialized tissue
   • division of labor
   • tissue
     • group of cells that specialize in the same way
     • more efficient
   • to carry out different fiunctions
   • 220 distinctive types in humans

6. Gene expression and cell differentiation

   • involves expression of some genes and not others
   • 25000 genes present in every human body cell
     • only some used
   • imp: control of gene expression

7. Stem cells

   • therapeutic uses
     • regenerate burnt tissue
     • healing diseases like diabetes
     • grow replacement organs such as kidney
   • embryonic development
   • cells that haven't differentiated yet
   • key properties
     • can produce copious amounts of new cells; rectify tissue damage
     • can differentiate in different ways
   • large amounts of meat for consumption without slaughter
   • once commited to pah of differentiation; no longer stem cells
   • adult stem cells in bone marrow, liver and skin
   • limited repair; brain, kidney and heart