Biochemistry example

I went to the recent open day at Nottingham uni, and in the Biochemistry lecture, the lecturer mentioned that in some areas of Biochemistry, it was previously thought that there was nothing new to learn, but actually many recent developments have been made (mainly due to technology). This part stuck in my head, but the examples used did not, and now I need to use an example for an article I am writing. I know this is a slightly strange request, but does anyone have any ideas?
I think it may have been something to do with mitochondria or the Golgi apparatus, but I'm open to other suggestions too
Please help!

There are loads of examples of things like this, not just in biochemistry, but in all sciences. Some that I can think of for biochemistry:

- Traditionally thought that a protein's function is defined by its 3 dimensional structure. Probably not true for about half of the proteome (Google: The Dark Proteome, intrinsically disordered proteins)

- Traditionally thought that the cytoplasm is just a big watery space that reactions happen in, notably glycolysis. Protein concentrations in the cytoplasm are very large, and most people had been studying reactions in test tubes with the concentrations diluted down massively. In reality, the situation is probably a lot more complicated and protein-protein interactions are very common between enzymes formerly thought of as 'discreet'. (Google: Substrate channelling, notably in the glycolytic pathway)

- A while ago everyone thought they knew how to identify flux controlling enzymes in a metabolic pathway, until Kacser, Burns, Heinrich & Rapoport came along and provided a sturdy mathematical framework for biochemical systems analysis (Google: Metabolic Control Analysis) which revealed that a lot of the enzymes thought to be flux controlling were in fact not, and control is shared throughout a pathway.

- For your mitochondria/Golgi apparatus example, maybe it was something about these not being discrete structures, whereas people used to think they were. Mitochondria are dynamic, they continually fuse together and fission apart. Fusion needs a membrane potential to occur, so it has been suggested that this constant assembly and dissassembly process is a sort of 'quality control' process.
Then structures like the Golgi apparatus & endoplasmic reticulum are similarly dynamic: the endoplasmic reticulum has a labelled cis end and trans end, based on the direction of where vesicles come in and out. It's now thought that the whole structure sort of pulls through itsself, so the cis part eventually becomes the trans part, and incoming vesicles form the cis part. So again, a complicated dynamic structure, not just a blob that things go into and out of like people used to think.

Thank you so much! This has been really helpful - if you don't mind me asking, how do you know all this? Are you a Biochemistry student?

yeah kindof, I do natural sciences at cambridge so I'm going into my third year specialising in chemistry (maybe chemical biologically inclined im not really sure), but last year I did a biochemistry & molecular biology option and the year before that a biology of the cells option

Please could you explain how/ why it is thought that the cycles of fusion and fission of mitochondria are related to quality control?
Maybe so that damaged parts of mitochondria can be removed after fusion and a healthy mitochondria can be formed upon fission?