Chapter 2

• Amino acids


  Monomers of a polypeptide chain
• Polypeptide chain


  • Hierarchical levels of structure that give rise to a functional protein
• Four major Biomolecules


  • Proteins
  • Carbohydrates
  • Lipids
  • Nucleic Acid
• Biomolecules are organic molecules (all contain CHO)
• Water


  Most abundant compound in organisms
• Water molecules


  • Highly cohesive, highly attracted to one another, stick together with hydrogen bonds
  • Adhesive
  • Acts as a solvent, substances that dissolve in a solvent are called a solute
  • Substances that dissolve in water are called hydrophilic or polar
  • Substances that don't dissolve in water are called hydrophobic or nonpolar
• Polymer


  Large organic molecules composed of many smaller repeating units (monomers) joined together in a long linear chain
• Monomer


  Single units of a polymer
• Carbohydrates


  • Monosaccharides: Glucose, Fructose, Galactose, ribose, deoxyribose
  • Disaccharides: Maltose, Sucrose, Lactose
  • Polysaccharides: Starch, Cellulose
• Carbohydrates


  • Can be monosaccharides, disaccharides or polysaccharides
  • Important source of energy
• Nucleic Acids


  Main information carrying molecule in a cell
• Nucleic Acids


  • Two main classes: DNA and RNA
  • Made up of nucleotides (monomers) which contain a nitrogenous base, a phosphate group and a sugar (monosaccharide ribose - RNA, deoxyribose - DNA)
• Lipids


  • Not true polymers
  • Insoluble in water (said to be hydrophobic or non-polar)
  • Made from fatty acids and glycerol
• Proteins


  • Do most of the work in cells and are required for the structure, function, and regulation of the body
  • Are made up of hundreds or thousands of amino acids, which are attached to one another in long chains
  • The sequence of amino acids determines each protein's unique 3-dimensional structure and its specific function
• Amino Acids


  • Monomers or subunits of proteins
  • Generally made of a central Carbon atom, to which are attached a Hydrogen atom, a carboxyl group (COOH), an amine group (NH2) and an R group
  • The R group in an amino acid varies and differentiates one amino acid from another and gives the amino acid its properties
• Protein formation


  1. Peptides: short chains of two or more amino acids bonded together (not folded)

  2. Polypeptides: long chains of many amino acids bonded together (not folded)

  3. Proteins are made of many polypeptide chains bonded together and the structure is folded

  4. Each protein has its own specific number and sequence of amino acids
• Polypeptide formation


  1. Polypeptide chains (polymers) contain a large number of amino acids bonded together by peptide bonds

  2. They are formed in the ribosomes

  3. The formation of peptides bonds is through condensation polymerization, a process where water is released (this reaction requires energy)