Summary of Protein Structure - Video Tutorials & Practice Problems
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Summary of Protein Structure Concept 1
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Hey, everyone. So in this video, we're gonna take a look at a summary of our different protein structures. Now we're going to say that proteins are very complex molecules with four levels of structural organization. And the first one, we're gonna talk about our primary structure. Now remember the characteristics of our primary structure is that is just a sequence of our amino acid. All these amino acids are linked together or stabilized by peptide bonds. Next, we move on to our secondary structure. We're still dealing with our same peptide chain. And we're gonna say this peptide chain can basically coil upon itself to create alpha helices or it can basically orient itself where we create beta pleated sheets. Now, here we're going to say the characteristics here is that it's a spatial arrangement of the polypeptide chain. Here, we're gonna say that it's stabilized by the fact that we have hydrogen bonds between the backbone atoms. Next, we move on to our tertiary structure. Here we have our hydrophobic interactions that kind of cause the peptide chain to turn in on itself where the hydrophobic portions will be on the interior of the chain. Now, here we're gonna say the overall shape of the folded polypeptide chain is the characteristics when it comes to the tertiary structure. Now, here, we're going to say that it's stabilized by, we're gonna say that it's stabilized here by four non covalent interactions and one covalent bond. The four non covalent interactions include hydrophobic interactions as well as hydrophilic. So the hydrophobic portions will orient themselves on the interior of our chain and the hydrophilic portions which like water would orient themselves on the outside. Now, in addition to this, we'd have hydrogen bonding involved and then our salt bridge, our covalent bond is when we have our disulfide bridge. Finally, we'd have our quaternary structure, which is the most complex level of our protein structure. We're gonna say this is the association of two or more sub units. So remember just think of the quaternary structure as building on top of the tertiary structure, we'd have multiple polypeptide chains kind of coming together to form this fully functional protein. Now, here we're going to say because it is building off of the tertiary structure, we're gonna say that it's stabilized by the same interactions as in a tertiary structure. So this is what we can say in summer when it comes to organizing proteins all the way from the primary structure up to the quaternary structure.
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example
Summary of Protein Structure Example 1
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During this example question, it says, determine whether each of the following statements describes the primary secondary tertiary or quaternary structure of a protein. For the first one, it says side chains interact to form disulfide bonds. So remember, disulfide bonds are a key characteristic of a tertiary structure. So here this represents a tertiary structure. Next peptide bonds join amino acids into a polypeptide chain. This is how we begin our journey towards a fully functional protein. This represents our primary structure. Remember amino acids form these peptide bonds with one another forming and linking together to form a long peptide chain. Next two peptide chains are held together by hydrogen bonding. All right. So they're talking about two chains now here that couldn't be primary or secondary because remember those happen amongst one chain. So that means it's either gonna be tertiary or quaternary here. They're saying two polypeptide chains are held together by hydrogen bonding. This has to be a tertiary structure because here we can have these types of interactions that connect different chains with one another. Eventually, this will lead up to our Quain structure. Later on. Next hydrogen bonding between amino acids in the same polypeptide gives a coiled shape to the protein coiled shape. Is a reference to our alpha hela seeds or alpha helix. Remember that is indicative of a secondary structure. So this will represent our different types of protein structures based on these four statements.
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Problem
Problem
Determine which of the following statements describes a tertiary structure of a protein.
A
Three polypeptide chains interact to form a biologically active protein.
B
Hydrogen bonds form between adjacent segments of the backbones of the same protein to form its creased structure.
C
Nonpolar side chains are repelled by water and move to the interior of the protein.
D
Amino acids react in a condensation reaction to form a peptide bond.
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Problem
Problem
Indicate whether each of the following statements describes a primary, secondary, tertiary, or quaternary protein structure:
______ a) Hydrophobic R groups seeking a nonpolar environment move toward the inside of the folded protein.
______ b) Protein chains of collagen form a polypeptide chain composed of 3 alpha helices.
______ c) An active protein contains 4 tertiary subunits.
______ d) Two polypeptide chains held together by disulfide bridges.
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