Orders of protein structure: primary, secondary, tertiary, and quaternary. Alpha helix and beta pleated sheet.
Log in Kam 9 years agoPosted 9 years ago. Direct link to Kam's post “When we digest meals rich...” When we digest meals rich in protein, are we denaturing the proteins and "re-naturing" them through the help of chaperonins, or breaking it down to it's base amino acids and re-creating proteins using those? • (66 votes) Darmon 9 years agoPosted 9 years ago. Direct link to Darmon's post “Oftentimes, we are breaki...” Oftentimes, we are breaking them down to their amino acid bases and creating new proteins. This is because many of the proteins that are found in the human body are not obtained directly from food, rather we need certain proteins in the food so we can use their amino acids to build the necessary proteins. The human body does not produce all 23 required amino acids, so we need to get them from our food, by eating proteins that contain those amino acids. :) (97 votes) sewerrat616 9 years agoPosted 9 years ago. Direct link to sewerrat616's post “What is the N-terminus an...” What is the N-terminus and C-terminus mentioned in primary structure? • (20 votes) Vaishnavi 9 years agoPosted 9 years ago. Direct link to Vaishnavi's post “The N-terminus refers to ...” The N-terminus refers to the amino end of the amino acid with the nitrogen and hydrogens, and the C-terminus refers to the carboxyl group. Sean Collin 9 years agoPosted 9 years ago. Direct link to Sean Collin's post “In the Primary Structure ...” In the Primary Structure section when they're talking about Hemoglobin and sickle cell: "What is most remarkable to consider is that a hemoglobin molecule is made up of two α chains and two β chains, each consisting of about 150 amino acids, for a total of about 600 amino acids in the whole protein." What do they mean by two Alpha chains and two Beta chains? Do they mean two polypeptides in an Alpha helix shape and two polypeptides in a Beta pleated sheet shape? Or are they just calling two of the polypeptides "alpha" because they're both identical and the other two "beta" because they're also identical. I thought polypeptides could contain both Alpha helix's and Beta pleated sheets, if so you won't be able to call one polypeptide chain specifically one or the other. • (16 votes) tyersome 7 years agoPosted 7 years ago. Direct link to tyersome's post “Your second guess is corr...” Your second guess is correct – the two alpha chains are identical (as are the two beta chains). This nomenclature is confusing and the designation of alpha and beta chains has nothing to do with alpha helices and beta sheets! In fact, alpha- and beta-hemoglobins have very similar structures both of which are dominated by alpha-helices and have no beta sheet at all (see for example: http://www.rcsb.org/pdb/explore/jmol.do?structureId=2HHB&bionumber=1). And yes, many proteins have both alpha helices and beta sheets. (4 votes) juvaldez50 8 years agoPosted 8 years ago. Direct link to juvaldez50's post “It goes in depth about th...” It goes in depth about the structures, but lacks in explaining function. Besides holding other primary structure proteins, what does a tertiary and quaternary structure even do? • (8 votes) Katherine Lu 8 years agoPosted 8 years ago. Direct link to Katherine Lu's post “The function of tertiary ...” The function of tertiary and quaternary structure varies depending on type of protein, but in enzymes, the specific shape and configuration of the protein allows the formation of active sites. For example, catalase, an enzyme that breaks hydrogen peroxide into hydrogen and oxygen gas, has its proteins and amino acids configured in a certain way to create an area where the charges are so strong that spontaneous reaction occurs, by lowering the energy needed to break intermolecular bonds. (12 votes) Alyssia 6 years agoPosted 6 years ago. Direct link to Alyssia's post “A question that came to m...” A question that came to mind as I was reading this and watching the previous videos is: • (9 votes) tyersome 6 years agoPosted 6 years ago. Direct link to tyersome's post “This is a great question,...” 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. Each amino acid has unique chemical properties that can be used to tell them apart. There are many different techniques for directly determining protein sequences — this wikipedia article is a decent introduction: 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). However, it is now relatively rare to directly determine protein sequence! 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. (9 votes) Kaitlyn Melody 7 years agoPosted 7 years ago. Direct link to Kaitlyn Melody's post “I am slightly confused wi...” I am slightly confused with secondary structures. If the backbone determines the structure, how is it different from the tertiary structures? In other words, what are the main difference between each structure? • (5 votes) briancsherman 7 years agoPosted 7 years ago. Direct link to briancsherman's post “The secondary structure i...” The secondary structure is formed by hydrogen bonds between carbonyl and amino groups that make up the polypeptide backbone and causes the molecule to either bend and fold (beta pleated sheet) or spiral around (helicase). The tertiary structure is formed by many different bonds between R groups that make up the side chains, that make the strand of molecule bend and loop around in a more complicated three dimensional form. (9 votes) Sean Collin 9 years agoPosted 9 years ago. Direct link to Sean Collin's post “In the last paragraph the...” In the last paragraph they begin to talk about Proteins "folding" but they don't explain what this means. • (4 votes) Nick 9 years agoPosted 9 years ago. Direct link to Nick's post “Proteins can fold into va...” Proteins can fold into various structures/sizes (secondary, tertiary, quanternary) for various biological tasks. Think of it literally as proteins folding into smaller, more condensed forms. (5 votes) Jack Lance 8 years agoPosted 8 years ago. Direct link to Jack Lance's post “In the subsection on Tert...” In the subsection on Tertiary Structure, it is mentioned that Disulfide bonds are much stronger than the other types of bonds contributing to Tertiary Structure of proteins. What is it about these S-S linkages that makes them so strong? And in relation to that: What determines whether or not an ionic/covalent bond is strong or weak? • (5 votes) Amirhossein Alesheikh 6 years agoPosted 6 years ago. Direct link to Amirhossein Alesheikh's post “In the sickle cell anemia...” In the sickle cell anemia example, is it the case that a key amino acid difference may cause catastrophic results or is it the case for that all amino acids are that important and changing any of them may cause similar catastrophic results? • (4 votes) RogerP 6 years agoPosted 6 years ago. Direct link to RogerP's post “Sickle cell anaemia is ca...” Sickle cell anaemia is caused by a single point mutation of the gene coding for haemoglobin. As a result, a hydrophobic amino acid (valine) replaces the usual hydrophilic amino acid (glutamic acid). This very small change in sequence affects the outside of the protein and results in haemoglobin molecules sticking together, changing the shape of the cell. There are lots of other known mutations in the haemoglobin gene, some which affect health and others which have no impact. In summary, for any particular protein, some amino acids are far more important than others. (4 votes) connerjamesstarnes a year agoPosted a year ago. Direct link to connerjamesstarnes's post “What duos it mean by dena...” What duos it mean by denatured? • (4 votes) Mason Smith a year agoPosted a year ago. Direct link to Mason Smith's post “In biochemistry, denatura...” In biochemistry, denaturation is a process in which proteins or nucleic acids lose the quaternary structure, tertiary structure, and secondary structure which is present in their native state, by application of some external stress or compound such as a strong acid or base, a concentrated inorganic salt, an organic solvent, agitation and radiation or heat. If proteins in a living cell are denatured, this results in disruption of cell activity and possibly cell death. But in the "Denaturation and protein folding", I think they were talking about if the pH or temperature of a proteins environment was to change, the shape of the protein (I think) would change also, and when that happens, the protein is going to turn back into an unstructured string of amino acids. And when a protein loses it's high order structure (but not the primary one) it is called denatured. (3 votes)Want to join the conversation?
How do we know what amino acids look like? For example, we learned that there are two amino acids switched out which causes sickle cell anemia. How did we learn that and how do we know which amino acids that is?
We don't see the letters "C", "H", "S", "N", etc when we look through microscopes at proteins, so how did we get so advanced to understand protein interactions? It's fascinating!! Thanks!
There are also methods that have been developed to remove amino acids one at a time.
By combining theses techniques it is possible to directly determine protein sequences.
https://en.wikipedia.org/wiki/Protein_sequencing
Instead, since it has been worked out (mostly) how DNA codes for protein, we usually infer the protein sequence from the DNA sequence. This is because it is now much easier to sequence DNA.
