In my opinion, the three major themes covered in this biochemistry course are metabolism, protein structure and function, and DNA replication.  Each one is connected to multiple lectures throughout the semester.  Metabolism was covered in the last few lectures and chapters with glycolysis, the citric acid cycle, the electron transport chain, and the structure of the mitochondria.  Protein structure and function was covered during the early portion of the semester when we discussed primary (nucleotide), secondary (amino acid composition), tertiary (hydrogen bond interaction and folding), and quarternary (subunit interaction) structure, enzymes, and DNA.  DNA replication was a major topic during the middle of the semester when we discussed translation, transcription, reverse transcription, and all the inclusive enzymes which catalyze such functions.  I have learned about DNA replication before however not to the depth covered in our class.  I did not know that one strand was continuously replicated while the other was in portions or Okazaki fragments.  All the topics were quite interesting and I enjoyed learning about them.