Monomers vs molecules vs polymers

[cjavier70]

I am having trouble understanding the building blocks of monomers and molecules. Can anyone please validate the following assumptions?

 

1) A monomer is always a molecule

2) Not all molecules are monomers

3) A polymer is a macro molecule

4) Not all macromolecules are polymers

[DrP]

Those statements, 1 to 4, are correct. What else do you need to know?

[CharonY]

Hmm what would be an example of a non-polymeric macromolecule?

[DrP]

Hmm what would be an example of a non-polymeric macromolecule?

 

Dendremers? Some large biological molecules and systems maybe? Some amorphous solids, if you don't class them as polymers already that is. What do you think? I'd have to look it up to be more certain I think as it has been a while

[BabcockHall]

Hmm what would be an example of a non-polymeric macromolecule?

Lipids fall into a gray zone for me. They are big, but they are typically not as big as other biological macromolecules, such as proteins and RNA. I can't think of any that are polymers, exactly, although triacylglycerols have three fatty acyl groups. Cholesterol is not really a polymer in my mind, although perhaps some isoprenoids are.

[CharonY]

All dendrimers that I can think of are polymers. Lipids could fit the bill, though.

Edited January 27, 2015 by CharonY

[DrP]

I don't think you can class the lower molecular weight dendrimers as polymers. http://en.wikipedia.org/wiki/Dendrimer

 

Lipids definitely. What about Gels? Not sure you can call all gels polymers.... but they are essential one giant molecule filling the volume of their mass, like the amorphous solids... so definitely macromolecules.

[Fuzzwood]

http://en.wikipedia.org/wiki/Macromolecule

[John Cuthber]

Hmm what would be an example of a non-polymeric macromolecule?

I can invent a lot of different amino acids.

if I make a polypeptide in which no amino acid appears twice is it a polymer?

It's not made from a monomer. no "mer" is present more than once so there's no "poly" about it.

 

Is a diamond a macromolecule?

Is it a polymer?

 

A lot of these depend on exactly what definition you use.

I think most polymers are based on repeating monomer units- but it's not clear if that's the defining property,or just the way most of them are made.

[CharonY]

Hmm good points. To be honest, I never thought about it that way. I guess in biology the term is used rarely and also loosely, more from the viewpoint of the synthesis (i.e. polymerization) than from the end product.

[DrP]

Crystal structures? Macromolecular, but not really polymeric. (Sorry John, you maybe covered that with diamond already - was just thinking about crystals, remembered this thread and decided to log on).

[BabcockHall]

A typical polypeptide or nucleic acid is a heteropolymer. Something like starch is a homopolymer (only glucose residues).

Edited February 5, 2015 by BabcockHall