ser vs rer
smooth endoplasmic reticulum (ser) vs rough endoplasmic reticulum (rer). i mean, isn't it in the name? one's smooth and one's rough! get your head in the game.
yeah, but it's not that simple. the roughness merely denotes the presence or absence of ribosomes along the walls, but there are several more differences, my friend.
take a look for yourself.
one looks like bubbles and the other like a maze. hmm, i wonder why this is the case.
the ser is described to be more TUBULAR than the rer, because in 3d they look like this:
wow. the ser kind of reminds me of centrioles
anyways. you can see that the rer has more cisternal space (the space enclosed by the membrane) than the ser. that's because the rer needs space to allow polypeptide chains to fold properly. it's a very complex dance, you see.
molecular chaperones are present in the cytoplasm and, more importantly for this, the rer lumen. they bind to and assist newly synthesised polypeptides to fold them into their three dimensional conformation, which is where they gain their function (mostly).
other ways proteins gain function is via phosphorylation (addition of a phosphate group, which is negatively charged and enhances affinity to positively charged molecules) and removal of a section of amino acids (eg. removing the C section of insulin)
as for the ser, it focuses more on synthesizing fats and steroids (natural ones!), churning the ingredients in the little tubes like a witch's cauldron.
the ser requires higher surface area to volume ratio, hence the tubular structure which resembles a pipe network. more membranes means more space to embed enzymes which are required for its function (above) and detoxifying poisons and drugs.
