3.1 3.3


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3.1 3.3

  1. 1. Pearson, Chris, Haziq, Abenazer3.1Water is a universal element that is mostly present everywhere on the earth. Water contains propertiesthat we must include thermal, cohesive, solvent that we must include. Water is the solvent of life. Watercontains hydrogen and oxygen atoms held by polar convent bonds.Thermal propertiesWater can absorb or give off a great deal of heat without changing temperature greatly. All living thingsare composed of a great deal of water and thus you can think of water content as a temperaturestabilizer. Water also has a high heat of vaporization. This means that water absorbs a great deal ofheat when it evaporates.Cohesive PropertiesThis attraction is due to the polar covalent bonding mentioned earlier. Water molecules have a positiveend and a negative end. Whenever two molecules are near each other the positive pend of one attractsthe negative end of another. When water cools below the freezing point, molecular motion has slowedto the point where these polar attractions become locked into place and ice crystals. Liquid water hasmolecules with a much faster molecular motion and the water molecules are able to influence eachother, but not to the point where molecules stop their motion.Solvent PropertiesWater is a universal solvent. It is an excellent solvent for polar molecules, most of which are found onthe inside and outside of most cells, including carbohydrates, proteins, nucleic acids (DNA and RNA).Water is also used for most of the cells biochemistryBecause water is an excellent solvent for biochemically important molecules, it is also the medium inwhich most of the biochemistry of a cell occursVascular tissue in plants carries water and a variety of dissolved substances.Xylem carries water and dissolved minerals up from the root system to the leaves of a plantPhloem then transports dissolved sugars from the leaves to the stems, roots and flowers of a plant.Blood is the most common transport medium in animals and is largely made up of waterBlood is a transport medium for red blood cells, white blood cells, platelets and a wide variety ofdissolved molecules.
  2. 2. Pearson, Chris, Haziq, Abenazer3.2Carbohydrates, lipids and proteins Living things are composed of an amazing array of molecules Molecules of the same type have certain qualities in common and become fairly easy to recognize with a little practice. Molecules can be classified as being either inorganic or organic. All organic molecules contain the element carbon, although not all carbon-containing molecules are organic. Carbohydrates are among the most commonly found biochemical molecules found in both animals and plants Carbohydrates exist in different ‘sizes’ – monosaccharide, disaccharides, and polysaccharides. Lipids are biochemically important molecules that serve many functions; we refer to triglyceride lipids in solid form as fats. In liquid form, triglycerides are called oils. If you eat more food than you burn, your body will store much of the excess as fat in adipose cells Carbohydrates are also used for storing energy in living organisms. Lipids are also important for thermal insulation A special category of lipids called phospholipids makes up the double layer of all cell membrane. These phospholipids molecules have a polar end turned towards water and a non-polar end which turns away from water. Food is chemically digested in your alimentary canal. The digestive enzymes that accomplish this are hydrolyzing enzymes. Each reaction is called a hydrolysis and requires a molecule of water as reactant. Condensation reactions are in many ways the reverse of hydrolysis reactions. In cells, condensation reactions occur to re-form the larger biochemically important molecules.
  3. 3. Pearson, Chris, Haziq, Abenazer 3.3 Avery – Proved Griffith’s transforming principle by removing protein from the experiment. Griffith – Transforming principle – change in strains Hershey & Chase – Dyed DNA and surrounding proteins in different colors to prove that DNA was the genetic material. Hydrogen Bonds between nucleotides Covalent bonds between Sugar and phosphate and between nitrogenous bases DNA nucleotides linked together by covalent bonds DNA Structure is by four nucleotides A T C G which are connected by hydrogen bonds, with phosphate and sugar chained linked together forming a double helix structure.