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• Proteins


  Key structures found in all living things that are made up of chains of amino acids

  
• Composition of amino acids

  • Carbon
  • Oxygen
  • Hydrogen
  • Sulfur
• Proteins come in a wide array of structures, each serving their unique functions
• Functions of proteins


  • Enzymes
  • Catalysts
  • Hormones
  • Providing structure
  • Transport
  • Defense
  • Contraction
  • Storage
• Simple proteins


  Yield only amino acids upon hydrolysis
• Conjugated proteins


  Yield other compounds aside from amino acids upon hydrolysis
• Fibrous proteins


  • Long polymer chains are arranged parallel or nearly parallel to one another to give long fibers or sheets
• Globular proteins


  • Fold back on themselves to produce compact, nearly spherical shapes
• Membrane proteins


  • Transport substances throughout the body in blood or lymph
• Functions of proteins


  • Enzymes
  • Hormones
  • Structure
  • Defense
  • Contraction
  • Storage
• Primary structure


  The sequence of amino acids in a polypeptide chain

  
• Amino acids


  The monomers that make up proteins
• Peptide bond


  Covalent bond formed by linking of amino acids in a dehydration synthesis reaction

  
• Secondary structure


  Local folded structures that form within a polypeptide due to interactions between atoms of the backbone
• Tertiary structure


  The overall three-dimensional structure of a polypeptide
• Quaternary structure


  When a protein is made up of multiple polypeptide chains, also known as subunits

  
• Protein-protein interactions


  Physical contacts of high specificity established between two or more protein molecules
• Complex formations


  Complex proteins made up of 2 or more polypeptide chains connected for a certain function
• Protein synthesis


  1. Transcription

  2. Translation

  3. Post-translational modifications
• Transcription


  The process of creating an mRNA molecule from a DNA template
• Initiation


  The beginning of transcription when RNA polymerase binds to the promoter region
• Elongation


  The stage when the RNA strand gets longer as new nucleotides are added
• Termination


  When a polyadenylation signal appears in the RNA transcript, marking where the transcript should end
• Pre-mRNA processing


  Modifications to the mRNA in the nucleus before it is ready for translation
• 5' cap


  Added to the beginning of the mRNA
• 3' poly-A tail


  Added to the end of the mRNA
• Exons


  Gene segments that encode a protein
• Introns


  Gene segments that do not code for proteins
• Splicing


  The process of removing introns and joining exons together
• Translation


  The process of using the mRNA to direct the synthesis of a protein
• Start codon


  AUG, codes for the amino acid methionine
• Stop codons


  UAG, UAA, UGA, signal the end of translation
• Ribosome


  • Decodes the genetic message, catalyzes peptide bond formation, has binding sites for mRNA and tRNA
• Steps in translation


  1. Initiation

  2. Elongation

  3. Termination
• Post-translational modification


  Chemical changes that occur after a protein has been produced, can impact structure, electrophilicity and interactions
• Types of post-translational modifications

  • Glycosylation
  • Phosphorylation
  • Ubiquitination
  • Proteolysis
  • Protein methylation
  • Acetylation
  • Lipidation