week 7

• Four biomolecules


  • Carbohydrates
  • Proteins
  • Lipids
  • Nucleic acids
• Monosaccharide


  Simplest sugar
• Glycosidic bonds


  Covalent bonds that bind together monosaccharides to form polysaccharides
• Biomolecules in starches and fibers

  • Carbohydrates
• Lipids


  Responsible for insulation and energy storage
• Enzymes


  Belong to the biomolecule group of proteins
• Nucleic acid


  Function is to store genetic information
• Cell membranes


  Made up of the biomolecule lipids
• Functions of lipids


  • Long term energy storage
  • Protection against heat loss (thermal insulation)
  • Protection against physical shock
  • Protection against water loss
  • Chemical messengers (hormones) and signaling molecule
  • Major component of the cell membrane structure (phospholipids)
• Fats and oils


  Also called triglycerides or triacylglycerols, the most abundant lipid compounds
• Lipids


  • Phospholipids
  • Waxes
  • Steroids
  • Prostaglandins
• Saponifiable lipids


  Can be hydrolyzed by a base (e.g. fats, oils, waxes)
• Nonsaponifiable lipids


  Cannot be broken down by basic hydrolysis (e.g. steroids, cholesterol, prostaglandins)
• Functions of lipids


  • Long term energy storage
  • Protection against heat loss (thermal insulation)
  • Protection against physical shock
  • Protection against water loss
  • Chemical messengers (hormones) and signaling molecules
  • Major component of the cell membrane structure (phospholipids)
• Fats and oils


  Also called triglycerides or triacylglycerols. Fats are usually solid at room temperature, oils are liquids.
• The presence of double bonds in the fatty acids of oil significantly lowers its melting point.
• Fats and oils have similar molecular structures, made up of esters of glycerol with three fatty acid molecules.
• Saturated fatty acids


  Fatty acid chain with only single bonds between neighboring carbons
• Unsaturated fatty acids


  Fatty acid chain contains a double bond
• Waxes


  Esters of long chain fatty acids and monohydric alcohols. Harder and less greasy than fats, with high melting points.
• Waxes


  • Repellency, impermeability, low toxicity and odor make them excellent coating materials
  • In plants, serve as protective covering (cuticle) against microorganisms and retard water loss
  • In animals, coat skin, hair and feathers to keep them pliable and waterproof
  • In humans, produced by glands in the outer ear canal to trap dust and dirt particles
• Phospholipids


  Form part of the structure of cell membranes, significant in the transport of lipids in the body. Have a glycerol backbone attached to fatty acids ("tails") and one fatty acid replaced by a phosphate "head".
• Lecithin


  An example of a phospholipid that plays an important role in fat metabolism in the liver and is a good emulsifying agent.
• Steroids


  Lipids characterized by three cyclohexane rings and one cyclopentane ring. The functional group attached to the rings varies.
• Sterols


  • Cholesterol (sterol formed in brain tissue, nerve tissue and blood)
  • Testosterone (male hormone that promotes normal development of male genital organs and other male characteristics)
• Prostaglandins


  Unsaturated carboxylic acids biochemically synthesized from the fatty acid, arachidonic acid. Consist of 20 carbons and a five-member ring. Resemble the effect of hormones and are considered as potent biological agents.
• Fevers and inflammatory reactions are produced by prostaglandins, and aspirin can suppress their synthesis.
• 20 naturally occurring amino acids

  • Glycine (Gly)
  • Alanine (Ala)
  • Valine (Val)
  • Isoleucine (Ile)
  • Leucine (Leu)
  • Methionine (Met)
  • Phenylalanine (Phe)
  • Proline (Pro)
  • Tryptophan (Trp)
  • Serine (Ser)
  • Threonine (Thr)
  • Tyrosine (Tyr)
  • Cysteine (Cys)
  • Asparagine (Asn)
  • Glutamine (Gln)
  • Aspartic Acid (Asp)
  • Glutamic Acid (Glu)
  • Lysine (lys)
  • Histidine (His)
  • Arginine (Arg)
• Amino acid


  Contains both an amino group (-NH2) and a carboxyl group (-COOH)
• 1. group (side chain) of amino acid


  Influences the property of the biomolecule. Can be nonpolar/hydrophobic, aromatic, basic, or acidic.
• Amino acids in solution


  Exist as dipolar ions (zwitterions) - carry both positive and negative charge. Effective buffers in aqueous solution.
• Levels of protein structure


  • Primary structure (sequence of amino acids)
  • Secondary structure (regular geometric patterns like helix or pleated sheet)
  • Tertiary structure (three-dimensional folding)
  • Quaternary structure (how individual polypeptide chains fit together)
• Proteins are defined by their structures, which give the proteins their identifying properties such as solubility, reactivity of the R-group, molecular weight and size.
• Nucleic acids


  Large molecules for storage and transmission of genetic information. Linear sequences that code for hereditary traits by controlling protein production.
• Nucleotide


  Monomer of a nucleic acid. Comprises a nitrogen-containing base, a five-carbon sugar, and a phosphate group.
• Roles of nucleotides


  • Serving as energy stores (ATP)
  • Forming coenzymes
  • Mediating cellular processes
  • Controlling enzymatic reactions
  • Serving as activated intermediates in biosynthetic reactions
• Nucleoside


  Combination of a nitrogen-containing base and a five-carbon sugar, without the phosphate group.
• Nitrogen-containing bases in nucleic acids


  • Pyrimidines (cytosine, thymine, uracil)
  • Purines (adenine, guanine)
• Sugars in nucleic acids

  RNA contains ribose, DNA contains deoxyribose
• Phosphate group in nucleotides

  Serves to link nucleotides together into a polynucleotide chain