While you are probably already familiar with carboxyl groups (COOH) and amine groups (NH2), the so-called R group may be new to you. Proteins are a type of complex macromolecule built up of monomers called amino acids that are linked into complex polymers by bonds known as peptide bonds.Īmino acids are formed by attaching an amine group, a carboxyl group, and a variable (R) to a central atom of carbon. After reading through this AP® Biology Crash Course Review, as well as the practice questions and quick recap at the end, you should feel that you have a good understanding of what proteins are and that you are ready to tackle that AP® Bio exam! What Are Proteins?
While you hear a lot about proteins in daily living – like in ads for protein shakes and protein powders– there are a few misconceptions about why proteins are important and how they work. Note that because of processes such as the post-translational modifications to proteins we still need protein sequencing and I believe that we currently rely too heavily on DNA sequencing.Proteins, along with carbohydrates and lipids, are a type of organic macromolecule that are fundamental building blocks of life.
This is because it is now much easier to sequence DNA. Instead, since it has been worked out (mostly) how DNA codes for protein, we usually infer the protein sequence from the DNA sequence. However, it is now relatively rare to directly determine protein sequence! The very first protein sequence (bovine insulin) was determined by Fredrick Sanger in 1951-2 (note that this was more than a decade before the first nucleotide sequence). There are many different techniques for directly determining protein sequences - this wikipedia article is a decent introduction: There are also methods that have been developed to remove amino acids one at a time.īy combining theses techniques it is possible to directly determine protein sequences. This is a great question, but actually quite complicated so I'm not going to try to give a complete answer - I have given some useful links below if you wish to learn more.Įach amino acid has unique chemical properties that can be used to tell them apart.
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