DNA, Genes and Chromosomes

• Describe the structure of proteins (5 easy marks !)

  A polymer of amino acids which are joined by peptide bonds formed by a condensation reaction. The primary structure is the order of amino acids. The Secondary structure is the folding of polypeptide bonds due to hydrogen bonding. The tertiary structure is the 3D folding of polypeptide bonds due to hydrogen, ionic and disulfide bonds. The quaternary structure is the folding of two or more polypeptide bonds.
• What do endopeptidases, exopeptidases and dipeptidases do in the human gut?

  Endopeptidases break protein polypeptide chains into smaller peptide bonds. Exopeptidases remove terminal amino acids. Dipeptidases hydrolyse dipeptides into amino acids.
• Describe how proteins are digested in the human gut (VERY similar to the flashcard about endo, exo and di!!)

  Hydrolysis of peptide bonds. Endopeptidases break polypeptides into smaller peptide chains. Exopeptidases remove terminal amino acids. Dipeptidases hydrolyse dipeptides into amino acids.
• How do histone proteins help in the coiling of DNA? (Eukaryotic cells)

  The DNA strand wraps around a packaging proteins called histones. When the DNA is wrapped up , it will take up less space within the nucleus