I have never heard of straigthforward definitions of these fields in my college lectures, and the Internet searches were not very helpful. However, from what I have learned at different subjects, this what I understand of the following areas.

  • Biochemistry: The study of metabolic pathways, enzyme kinetics, bioenergetics and the chemical mechanisms of the reactions. It does study molecular structure, but only of small molecules such as monomers, metabolites and coenzymes.
  • Molecular biology: The study of information pathways, such as transcription, splicing and replication. It applies as well to techniques such as PCR.
  • Molecular genetics: The study of how a genotype creates a particular phenotype. For example, it would be the study of why an allele produces smooth peas while another one produces wrinkled ones.
  • Structural biology: Elucidating the structure of macromolecules (proteins, nucleic acids) and their complexes. It uses X-ray crystallography, NMR and cryo-electron microscopy to study them.

So, are my definitions accurate? If not, why?

  • 3
    $\begingroup$ They are not accurate. Why? 1. Because they are inaccurate 2. Because the fields overlap and people call themselves what they like (or what seems trendy) — I won’t elaborate on that one. I seem to remember answering (i.e. not answering) a question of this sort before. You might try searching for it. It was very good. $\endgroup$
    – David
    Commented May 7, 2019 at 18:07
  • 1
    $\begingroup$ @BryanKrause Because I'm curious. $\endgroup$
    – user38945
    Commented May 9, 2019 at 14:43
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    $\begingroup$ @Jagoe My point is basically the same as David's: the distinctions between these labels are not important to biology. There is also no specific definition that everyone would agree on without allowing that the borders are fuzzy and not meaningful. $\endgroup$
    – Bryan Krause
    Commented May 9, 2019 at 15:40
  • 1
    $\begingroup$ The question I recalled turned out to be on the term Biophysics, but the answer I gave illustrates my point. $\endgroup$
    – David
    Commented May 9, 2019 at 15:49
  • 1
    $\begingroup$ I was aware that the different areas overlapped, but I thought that their different names reflected the scope of each of them. $\endgroup$
    – user38945
    Commented May 9, 2019 at 16:42


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