The Cell

The Cell

1. Water (70-80% except fat cells)

2. Electrolytes

   • Ions
     • K, Mg, P, S, Na, Cl, Ca
     • Provide inorganic chemicals for cellular reactions
     • At cell membrane
       • Transmit electochemical impulses in nerve and muscle fibres

3. Proteins

   • 10-20% of cell mass
   • Structural
     • Long filament polymer
       • form microtubules that provide cytoskeleton of
         • cilia
         • nerve axons
         • mitotic spinals of mitosing cells
         • thin filament tubules hold cytoplasm and nucleoplasm together
     • Extracellular
       • fibrillar proteins
         • collagen
         • elastin fibres
           • In blood vessels, tendons, ligaments
   • Functional
     • Enzymes
       • Mobile in cell
       • Adherent to membranous structure inside cell

4. Lipids

   • 2% of cell mass
   • Phospholipids
   • Cholesterol
   • Triglycerides/neutral fat
     • 95% of fat cells
     • Storehouse of energy

5. Carbohydrates

   • Structural function
     • glycoprotein
   • Nutrition
   • Readily available
   • Stored as glycogen (insoluble polymer)

6. Cell Membrane

   • Proteins (55%)
     • Glycoproteins
     • Peripheral
     • Integral
       • Structural channel/pores
         • Carrier proteins
         • Receptors
           • Eg. for peptide hormones
           • Ligands bind to receptors
             • Cause conformational change
         • Have selective properties
   • Phospholipis (25%)
   • Cholesterol (13%)
   • LIpids (40%)
   • Carbohydrates (3%)
     • Glycoproteins
     • Glycolipids
     • Proteoglycans
       • carbohydrates bound to small protein cores
     • Glycocalyx
       • Attaches to glycocalyx of other cells attaching cells together
     • Uses
       • Have -ve charge so repel other -ve objects
       • Receptor
         • for binding hormones, such as insulin
           • Activates a cascade of intracellular enzymes
       • Cell-cell recognition
         • moieties enter immune reactions
       • Important in organ and tissue develepment