Primary Protein Structure - Online Tutor, Practice Problems & Exam Prep

The primary structure of a protein is defined by the sequence of amino acids linked by peptide bonds, extending from the N-terminus to the C-terminus. Each amino acid, or residue, contributes to the peptide backbone, represented by the repeating N-C-C sequence. This backbone can coil or bend, leading to higher levels of protein structure. Understanding this sequence is crucial for grasping protein function and interactions, as the specific arrangement of amino acids determines the protein's properties and biological roles.

Primary Protein Structure Concept 1

In this video, we're going to take a look at the primary structure of a protein. Now we're going to say that the primary structure of a protein is the sequence of amino acids attached through peptide bonds. Now the structure is represented from the N-terminus end to the C-terminus end. If we take a look here at this sequence of amino acids, we see that on the left side, this is our N-terminus end, which is why we're pointing towards the amino group. And then on the right side, this is the C-terminus end and we're pointing towards this carbonyl, which was once part of a carboxyl group.

You'll notice that we have these squiggly lines. Remember, that just means that this amino acid is connected to other things. All we're doing is focusing on this segment of the sequence of amino acids. The same thing could be said here for this squiggly line. It's connected to something else.

We don't know what it is. We're just focused on this portion. Now, we're saying that we're dividing each one of these amino acids or residues with these dotted red lines. So we can see in this image we have, let's see. We, if we're ignoring these ends, we're gonna say we see 1, 2, 3, 4 of these different peptide bonds.

We see 4 peptide bonds if we're ignoring the ones on the end. We're gonna see that we have 5 residues. We're showing that there are 5 residues by showing that we have our 1 group, our 2, our 3, our 4, and our 5. Now, we're gonna say that the repeating N-C-C sequence forms the peptides' backbone. So, if you can see, we have NCC, NCC, NCC.

This is forming the backbone of our peptide. Now we're gonna say here, the backbone might either we're gonna see coil or bend to form our next level of protein structures. For now, we just need to remember that the primary structure of a protein is just a sequence of its amino acids connected through peptide bonds.

Primary Protein Structure Example 1

Which of the following statements about primary protein structure is incorrect? Peptide bonds that hold the amino acids together in the primary structure are covalent in nature. This is true because we see that it's the connecting of non-metal atoms to one another. So non-metal atoms or elements connected to each other is covalent in nature. So, this is true.

The peptide backbone is formed by a repeating N-C-C sequence. We also saw this when discussing the primary structure of a protein. This is true. The standard representation of primary protein is from N-terminus to C-terminus. This is also true.

So, then we use option D. The peptide backbone can have non-amino acid parts in addition to amino acid residues. Nowhere did we see, when it came to our primary structure of our protein, did we see anything other than amino acids being connected to one another through peptide bonds. We didn't see any of these non-amino acid components. So, this here is incorrect.

So, out of all the choices, the only one that's incorrect is option D.

Do the following peptides have an identical primary structure?

• A. Yes
• B. No