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
The discovery of the roles of enzymes as catalysts
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.
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 1953James 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:
Plasma - 8%
Interstitial and Lymph - 22%
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
Water molecule form dipoles
Water Molecules Form Hydrogen Bonds
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.