Thread: Is lipids macromolecules?

Is lipids macromolecules?

Originally Posted by Danieltan

Is lipids macromolecules?

Yes.

Originally Posted by TheBiologista

Originally Posted by Danieltan

Is lipids macromolecules?

Yes.

but when compare to carbohydrates and proteins,it seems not because small carbohydrate subunits(eg. glucose) and proteins subunits(amino acids) can form bonds by condensation to form an enormous structure(polymer),but however lipids do not.A single lipid molecule is just made up of fatty acids and glycerol,it does not forms polymer.Thus,its structure i not large enough.

The term macromolecule is applied to lipids, nucleic acids, proteins and carbohydrates in biochem.

Moreover, your understanding of lipids seems to be limited. You are forgetting the sphingolipids, saccharolipids, sterols, and hormones.

Woops..

Some hormones are proteins, no? Just a point of interest...

They are called peptide hormones.

Originally Posted by Danieltan

Originally Posted by TheBiologista

Originally Posted by Danieltan

Is lipids macromolecules?

Yes.

but when compare to carbohydrates and proteins,it seems not because small carbohydrate subunits(eg. glucose) and proteins subunits(amino acids) can form bonds by condensation to form an enormous structure(polymer),but however lipids do not.A single lipid molecule is just made up of fatty acids and glycerol,it does not forms polymer.Thus,its structure i not large enough.

After coming back, I see that you answer your own question as well.

Glycogen is a polymer made up of glucose monomers.

A protein is a polymer made up of amino acid monomers.

The extent to which how many monomers can be added onto the polymer doesn't determine what is a polymer. Lactose as a dimer formed of glucose and galactose is still a polymer despite being much smaller than most lipid molecules.

All a polymer is, is a molecule formed from repeating structural units, size does not come into play in this definition. In your question you named the repeating structural units that make up a lipid polymer.

I had receive so many different opinion from different teachers so i'm still not sure about it,so i search through a few website that gives the definition of macromolecules.However,most of them state that proteins,nucleic acids and polysaccharides are macromolecules but still some of them do mention that lipid is not.Please feel free to check these out...
1.http://www.whatislife.com/glossary/m.htm
2.http://www.lexicon-biology.com/biolo...nition_18.html
3.http://www.biology-online.org/dictionary/Macromolecules
And if possible can somebody provide me other websites about it?(That explain lipids are macromolecules)

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

Includes a pretty comprehensive explanation of the origins and definition of the term.

Originally Posted by Danieltan

I had receive so many different opinion from different teachers so i'm still not sure about it,so i search through a few website that gives the definition of macromolecules.However,most of them state that proteins,nucleic acids and polysaccharides are macromolecules but still some of them do mention that lipid is not.Please feel free to check these out...
1.http://www.whatislife.com/glossary/m.htm
2.http://www.lexicon-biology.com/biolo...nition_18.html
3.http://www.biology-online.org/dictionary/Macromolecules
And if possible can somebody provide me other websites about it?(That explain lipids are macromolecules)

None of those explanations says that lipids aren't macromolecules, they just list examples, one only mentions DNA and polysaccharides.

The one that says probably not phospholipids, does not preclude all lipids, despite the fact that most biochemist would consider phospholipids to be a macromolecule.

The wiki explanation is far better.

There are 4 main classes of important large molecules of all living things:

1.) Carbohydrates
2.) Lipids
3.) Proteins
4.) Nucleic Acids

Macromolecules are polymers, built from monomers. Lipids are the one class of large biological molecules that does not include true polymers, and they are generally not big enough to be considered macromolecules.

Monomers for:

1.) Carbohydrates are Monosaccharides
2.) Proteins are Amino Acids
3.) Nucleic Acids are Nucleotides

So, the answer to your question is: No, Lipids are not macromolecules.

I hope this explanation has helped.

A macromolecule isn't defined by whether it is a polymer or not. Besides lipids can form polymers in the case of triglycerides. Very small polymers, but still a polymer.

Definition of Macromolecules: giant molecules formed by the joining of smaller molecules, usually by a condensation reaction, specifically a dehydration reaction.

These smaller molecules are monomers which make up polymers; therefore, macromolecules are polymers.

And like I said before, lipids are the one class of large biological molecules that does not include true polymers.

Your definition is wrong, a macromolecule is simply a molecule with a large molecular mass. Lipids are almost always considered to be macromolecules in biochemistry.

Lipids are usually included in the biological macromolecules.

The definition of a macromolecule that I posted is not my own definition; it is from my University Textbook. Your sentences are wordy, and this makes your answers confusing for some people. Either Lipids are macromolecules or they are not. They can not be considered "almost always" macromolecules.

I don't need to repeat everything I said in my previous posts because it's straight forward, so I will end it here. It was nice discussing this topic with you. Good day.

You should learn not to accept what's written in books as dogma.

Biochemist include lipids in the definition of macromolecules.

The original definition proposed by the person who invented the term, was a molecule with over 1000 atoms.

When I say almost always, I'm implying that most of the time people define lipids as macromolecules.

Anyway, this is all pointless and I don't really understand why you bothered to resurrect a year old thread in the first place.