Biochem

• Enzymes


  Proteins that act as biological catalysts, speeding up chemical reactions without being permanently changed in the process
• Enzymes


  • Folded in specific shapes
  • Accelerate the rate of chemical reactions
  • Capable of performing multiple reactions (recycled)
  • Final distribution of reactants and products governed by equilibrium properties
  • Biological catalysts - mostly proteins, a few RNA exceptions
  • Orders of magnitude faster than chemical catalysts
  • Act under mild conditions (temperature and pressure)
  • Highly specific
  • Tightly regulated
• Substrate


  The substance (reactant) an enzyme acts on
• Enzyme-substrate complex


  The enzyme temporarily joins with the substrate during the metabolic reaction
• Active site


  Where the substrate temporarily fits into the enzyme during the metabolic reaction
• Induced fit


  A change in the shape of an enzyme's active site induced by the substrate
• How enzymes work


  1. Weaken chemical bonds, which lowers the activation energy

  2. Molecules can be built up or broken down by the body
• Enzymes end in -ase (e.g. sucrase, lactase, maltase)
• Factors affecting enzyme activity

  • Environmental conditions (temperature, pH, ionic concentration)
  • Cofactors and coenzymes
  • Enzyme inhibitors
• pH


  Indicates the concentration of H+ ions, with 7 being neutral, 0-6 being acidic, and 8-14 being basic
• Buffers


  Weak acids or bases that react with strong acids or bases to prevent sharp, sudden changes in pH, maintaining homeostasis
• Competitive inhibitors


  Chemicals that resemble an enzyme's normal substrate and compete with it for the active site
• Noncompetitive inhibitors


  Inhibitors that do not enter the active site, but bind to another part of the enzyme causing it to change shape and alter the active site
• Enzymes are important for their role in speeding up chemical reactions in the body
• Nucleotides


  Ubiquitous molecules
• RNA


  • Interprets information in DNA
  • Carries information to the ribosomes
  • Considerable structural diversity
• Varieties of Ribosomes


  • 8 common varieties
  • Where protein synthesis takes place
• Ribose


  Five carbon-sugar of RNA
• Deoxyribose


  • Five carbon-sugar of DNA
  • Deoxy means "without Oxygen"
• Bases of nucleotides


  • Planar, aromatic, heterocyclic molecules
  • Structural derivatives of either purine or pyrimidine
• Purines


  Adenine, Guanine
• Pyrimidines


  Cytosine, Thymine, Uracil
• Complementary base pairs


  • A-T, G-C
• DNA


  Preserves information in animals and plants
• Adenosine triphosphate (ATP)


  • Best known nucleotide
  • Energy storage, carrier and transfer agent
• Ribonucleic acid (RNA)


  Makes most of the nucleic acid found in cell
• Ribosomal RNA


  Most abundant type of RNA
• Nucleic acid


  Large molecules found in the nuclei of the cells that store information
• Transfer RNA


  Smallest of RNA molecules, interprets the genetic information in mRNA
• Deoxyribonucleic acid (DNA)


  Genetic materials in the nucleus of the cell, contains all information for development
• Only RNA can translate the genetic information in a living system into amino acids for proteins
• Genome


  Genetic information in the cell
• Acceptor stem


  Nucleotide sequence which is the end of a tRNA
• Replication


  Process where genome is copied exactly
• Anticodon


  Series of three bases of RNA that complement to the three bases of mRNA
• Genes


  Sections of DNA
• Transcription


  Synthesis of mRNA
• Translation


  mRNA to proteins
• Codons


  Series of nucleotides in mRNA
• Mutation


  Change in the nucleotide sequence of DNA