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cruz bio2 lectures
2:cellular chemistry
topic one:intro to the human body
topic 2: cellular chemistry

Bio2/ Topic Two: Cellular Chemistry


In this Hand- out:



            Molecules and Chemical Bonds

            Solutions and Properties of Solutions

            Organic and Inorganic Compounds


            All matter, living and non- living, consists of building units called chemical elements. Ninety- six percent of the human body is composed of the chemicals Carbon, Nitrogen, Oxygen and Hydrogen. Calcium, Phosphorous, Potassium, and Sulfur make up 3 percent of the body. The remainder of the body is composed of small quantities of Iron, chlorine, Iodine, Sodium, Magnesium, Copper, Manganese, Cobalt, Zinc, Chromium, Fluorine, Molybdenum, Silicon, and Tin referred to as trace elements.


  • atom:  smallest unit of an element that retains its chemical properties
  • elementary particles in an atom: protons, neutrons and electrons
  • atomic number: number of protons in the nucleus
  • atomic mass: number of protons + the number of neutrons (or 2x the atomic number)
  • molecule: combination of two or more atoms, joined by chemical bonds; smallest unit of a chemical compound
  • Bonds: attractive forces that hold molecules together
  • Types of bonds: ionic bonds, covalent bonds, hydrogen bonds


Solutions and Properties of Solutions


  • mixture: when two or more substances combine without forming bonds with each other
  • solutions: mixtures in which the molecules of all the combined substances are distributed homogenously throughout the mixture; include solids dissolved in liquid
  • molarity: measurement of the concentration of solute in a solution; measure of the moles of solute per liter of solution (1 mole= 6.022 x 1023 molecules)
  • pH: method of determining the acidity or basicity of the solution
  • Acid: substance that when added to water, increases the concentration of H+ ions
  • base: substance that when added to water increases the concentration of OH- ions
  • salt: an organic compound formed from the residue of an acid and the residue of a base
  • buffer: combination of a weak acid and its salt in a solution that has the effect of stabilizing the pH of the solution
  • 3 important buffer systems found in the body: bicarbonate buffer, phosphate buffer and the protein buffer


Organic and Inorganic Compounds


  • Inorganic compounds: do not contain carbon (exceptions include CO and Carbon dioxide)
  • Organic compounds: always contain carbon and are held together by covalent bonds.





  • Four families of Organic Compounds



Composed of carbon, oxygen, and hydrogen. Classified as monosaccharides, disaccharides and polysaccharies


Composed of fatty acids and glycerol


Composed of amino acids. The function of a protein is determined by the character of the amino acids it contains

Nucleic acids

Composed o f nucleotides containing a phosphate, a sugar, and a nitrogenous base

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