Intro to Biochemistry and Biomolecules

• Biochemistry - the study of the molecular basis of life or understanding life phenomena in chemical terms.
• 1770 - Antoine Lavoisier proposed that the combustion of a candle is similar to the respiration of animals, as both need O2.
• 1800 - “Vitalism” was a common belief: the compounds found in living organisms (i.e., organic molecules) can only be produced by living organisms and could not be produced in the laboratory.
• Friedrich Wöhler disproved this belief in 1828 by synthesizing urea, an organic molecule and a waste product of animal metabolism, from ammonium cyanate, an inorganic molecule obtained from mineral (i.e., nonliving) sources.
• Eduard Buchner's first demonstration of alcoholic fermentation in 1893 in cell-free yeast extracts as the starting point for the birth of biochemistry.
• Two Major Breakthroughs in the History of Biochemistry

  1. The discovery of the roles of enzymes as catalysts
  2. Identification of nucleic acids as information molecules
• The experiments of Buchner showing that extracts of yeast cells could catalyze the fermentation of the sugar glucose to alcohol and carbon dioxide.
• James Sumner showed that Enzymes are proteins (1920s-1930s).
• Emil Fischer explored the nature of enzymes as biological catalyst. He described the catalytic effect of yeast enzymes on the hydrolysis (breakdown by water) of sucrose (table sugar).
• 1928 - Griffith’s Transformation Experiment
• 1944 - Oswald Avery, Colin MacLeod, and Maclyn McCarty also provide evidence that DNA is the genetic material.
• Hershey and Chase Blender Experiment
• James Watson and Francis Crick DNA Model
• Griffith’s Transformation Experiment - The first experiment suggesting that bacteria are capable of transferring genetic information through a process known as transformation.
• Avery-MacLeod-McCarty Experiment - Demonstrated that DNA is the substance that causes bacterial transformation.
• Which is Virulent and Non-Virulent

  1. Smooth Strain - Virulent
  2. Rough Strain - Non-Virulent
  3. Heat-Killed Smooth Strain - Non-Virulent
  4. Rough Strain & Heat-Killed Smooth Strain - Virulent
• Which is Virulent and Non-Virulent

  1. Polysaccharides Destroyed - Virulent
  2. Lapid Destroyed - Virulent
  3. DNA Destroyed - Non-Virulent
  4. RNA Destroyed - Virulent
  5. Protein Destroyed - Virulent
• Alfred Hershey and Martha Chase in 1952, performed an experiment that proved that DNA was the carrier of information, permanently putting an end to this long standing debate.
• James Watson and Francis Crick’s DNA Model - The structure of DNA immediately suggested to Watson and Crick a method whereby DNA could reproduce itself, or replicate, and thus transmit biological information to succeeding generations.
• In 1953 James Watson and Francis Crick deduced the three-dimensional structure of DNA.
• Central Dogma of Molecular Biology - referred to this unidirectional information flow from nucleic acid to protein.
• Crick predicted in 1958 that the normal flow of information from nucleic acid to protein is not reversible.
• Chemical Basis of Life - We now know that, “life itself” is constructed from non-living matter (i.e., atoms and elements)
• Carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur (CHONPS) account for more than 97% of the weight of most organisms.
• Water is a major component of cells and accounts for the high percentage (by weight) of oxygen.
• Silicon, Aluminum, and Iron- very common in the Earth’s crust but are present only in trace amounts in cells.
• There are 23 other elements commonly found in living organisms and these include five ions that are essential in all species: Calcium, Potassium, Sodium, Magnesium and Chloride.
• The Fundamentals of Water - Water accounts for 60 – 95 percent of our living cells, and 55 percent of the water in the human body is in intracellular fluids.
• The remaining 45 percent (extracellular) is divided between the following:

  1. Plasma - 8%
  2. Interstitial and Lymph - 22%
  3. Connective tissue, cartilage, and bone - 15%
• Water - is the predominant chemical component of living organisms.
• Water - acts as a transport medium across membranes, carrying substances into and out of cells.
• Water - acts as a solvent (carrying dissolved chemicals) in the digestive and waste excretion systems.
• WATER IS AN IDEAL BIOLOGIC SOLVENT

  1. Water molecule form dipoles
  2. Water Molecules Form Hydrogen Bonds
  3. Water has a high specific heat
• Covalent bond - a bond where atoms share electrons; Bond is formed between atoms that have similar electronegativities.
• Overall interaction of a hydrogen atom bonded to either oxygen, nitrogen, or fluorine atoms with an oxygen, nitrogen or fluorine on another molecule (intermolecular) or the same molecule (intramolecular).
• Specific heat - is the amount of heat required to change the temperature of a gram of water 1° Celsius.
• Water is often called the universal solvent because it dissolves so many types of substances including: ionic substances (like KCl), alcohols and sugars.
• Hydrophilic (water-loving) - polar molecules have the ability to interact with water molecules.
• Hydrophobic (water-hating)- nonpolar molecules don’t appreciably interact with (dissolve in) water.
• Amphipathic - have both hydrophilic and hydrophobic regions.