MY QUESION
You guys know how there’s formulas for number of glucose monomer
180n - 18(n-1)
Or number of peptide links
(Amino acid monomers-1) correct next if wrong please
I was wondering where such a thing exists for tryclicerides at all? Thanks so much!!!
I mean, what would you want the equation to tell you? I can probably make one up, but it depends on what information you want to get from the equation. In some way, the answer is no - there is no equation, because the ones you're talking about are for polymers - triglycerides are not polymeric in the same sense. They don't have a repeating, regular, unit - they're three fatty acids (not necessarily the same acid, either!) attached to a glycerol backbone.
Personally, I'm not a fan of these equations, because they can often detach people from the physical chemistry that's actually happening. For example, WHY is the number of peptide links = number of monomers - 1? Well, think of it like links in a chain. If you have two loops in a chain, how many chain links do you have? Well, there's only two loops, so there must be a link between them - so you have one link. What if there's three loops? Well, you can think of this as having two loops - the big loop from before, and now one smaller loop. Two loops are easy - there's one link. BUT, there's also one link in the big loop from before, so in total, we have two links. What if there are four loops? Well, we have one big loop of three links, and another link - again, two loops are easy, there's one link. BUT, there's also two links in the big loop, so in total we have three links.
See the pattern? There's always going to be n-1 links in a chain of n loops - because the amount of links is just what happens when you put something between each loop. The same goes for peptides - the number of peptide links is just the amount of things you can put between each amino acid.
Okay, so what about the glucose equation? Well, 180n-18(n-1) tells you the molecular mass of a glucose polymer of size n glucose units. What are those numbers? Well, the molecular mass of molecular glucose (that is, the monomer) is 180 g/mol. The molecular mass of 18 is of water. So why would the total molecular mass be 180n-18(n-1)? Well, like the chain example, let's take this one step at a time. If I want to make a dimer, I have the equation:
This makes sense - what happens is two glucose units meet, and they make a link. To make that link, one molecule of water is removed - it's just like the chain example. That means that molar mass of this dimer should be what you get from both of those glucose monomers, minus the one water, yeah? Well, what about three glucose units? Similar equation:
So in this case, we have three glucose units, and we lose TWO waters - so the trimer's molar mass is going to be the molar mass of three glucose, minus the molar mass of two water. We can generalise this, but to do that we have to know - how many waters will we lose for n glucose molecules? Well, we just learned you lose water each time you have a link. How many links in n glucose monomers? Well, we learned from before - there's n-1. So, the total molar mass is 180*n, minus 18(n-1).
IMO, you should be able to derive these equations yourself - there's no mathematical trickery about them, it's just an application of the chemistry information.
Having said that, if there's an equation you want, I can still show you how you might create that equation - but hopefully this explains why you haven't seen one for triglycerides, and why you have for these other macromolecules.