2.1 - Molecules to metabolism

• • Carbon atoms contain four electrons in their outer shell allowing them to form four covalent bonds with potential four other different atoms, e.g. methane (CH4).
  • The result of these properties is an almost infinite number of different possible molecules involving carbon.
• • Covalent bonding occurs when pairs of electrons are shared by atoms. Atoms will covalently bond with other atoms in order to gain more stability, which is gained by forming a full electron shell. By sharing their outer most (valence) electrons, atoms can fill up their outer electron shell and gain stability.
• • Covalent bonds are the strongest type of bond between atoms.
  • Stable molecules can be formed.
• Because of the stability of covalent bonds large molecules with many bonds can be formed.
• Carbohydrates:

  • Contain carbon, hydrogen and oxygen
  • Organic compounds consisting of one or more simple sugars
  • Monomers follow the general basic formula of (CH2O)x
  • Monomers are commonly ring shaped molecules
• Lipids:

  • Lipids are a group of organic molecules that are insoluble in water but soluble in non-polar organic solvents
  • Common lipids include triglycerides (fats – solid at room temperature and oils – liquid at room temperature), phospholipids and steroids
• Proteins:

  • Contain carbon, hydrogen, oxygen and nitrogen (additionally sulphur is common component, but it is not present in all proteins)
  • Proteins are large organic compounds made of amino acids arranged into one or more linear chains
• Nucleic acids:

  • Contain carbon, hydrogen, oxygen, nitrogen  and phosphorus
  • Chains of sub-units called nucleotides
  • Nucleotides consist of base, sugar and phosphate groups covalently bonded together
  • If the sugar is ribose then the nucleic acid formed is RNA if the sugar is deoxyribose then DNA is formed
• Tryglycerides

  A) Stearic acid

  B) Linoleic acid

  C) glycerol

  D) carboxylic acid

  E) triglyceride

  
• Phospholipids - look just like triglyceride lipids except that one of the fatty acid chains is replaced by a phosphate (–P0 4 3–) group
• Steroids:

  • Are characterized by a backbone of four linked carbon rings
  • Examples of steroids include cholesterol and certain hormones, including testosterone.
• Amino acid

  A) R group

  B) Carboxyl group

  C) amine group

  
• Condensation makes bonds
• Hydrolysis breaks bonds
• Anabolic reactions are those which build molecules
• Catabolic reactions are those which break down molecules
• Condensation and Hydrolysis reactions require enzymes - biological catalysts
• Types of reactions:

  A) monomers

  B) synthase

  C) synthase

  D) polymer

  E) dimer

  F) hydrolase

  G) hydrolase

  H) Condensation

  I) Hydrolysis

  
• Maltose synthase condenses two molecules of glucose into maltose forming a glycosidic bond
• A ribosome condenses two amino acids into a dipeptide forming a peptide bond
• A protease hydrolyses a dipeptide into two amino acids breaking the peptide bond
• Lactase hydrolyses Lactose into Glucose and Galactose breaking the glycosidic bond
• A dehydration reaction is when the water molecule has come from ONLY one of the reactants.