What would happen if you change the amino acid sequence in a protein?
A protein is made up of a sequence of amino acids, which gives the protein it's primary structure (the order of amino acids in the protein), secondary structure (whether the amino acid forms alpha-helices, or beta-pleated sheets), tertiary structure (how the single amino acid chain folds up on itself) and quaternary structure (how separate amino acid chains join together sometimes with metals to form a big protein). When you change the sequence you will definitely change the primary structure (by definition), but whether you change the other structures depends on whether the sequence you change affects the bonding between the amino acids. If you substitute one amino acid with a very similar amino acid (amino acids can be grouped by the bonds they can form) the protein could continue to work as usual. However if you change one amino acid with a very different one, for example a hydrophilic amino acid for a hydrophobic amino acid, or one with a very short side chain for one with a very long side chain, it is likely that you will change the secondary structure, which could mean the protein can't function correctly.
What happens if you change a single amino acid in a sequence?
The other answerers are talking about base substitutions in the gene - and you are asking about amino acid substitution in the protein. The position in the primary sequence is almost entirely irrelevant - it is the amino acid's position in the final folded (tertiary/quaternary) structure of the protein that is crucial. For example, if the aa is a hydrophobic aa, which is normally found deep in the core of the protein, then changing it to a hydrophilic aa will probably dramatically disrupt the protein structure, and therefore its function also. If the aa is +ve, and you switch it for a -ve aa, this could have similarly dramatic effects on the final structure & function. Of course, you don't have to disrupt structure to disrupt function: if the aa is normally found at an active site, or a protein-protein association domain, and you swap it for another aa, then the protein could still *look* fine, but won't be able to perform the same function. That said - switching an aa for another with similar characteristics is likely to have the least disruption. This is by no means guaranteed: Ile and Leu are both hydrophobic, but their packing geometries are quite different, and if a tight packing of amino acids is required, then swapping the two could still disrupt the folded shape.
In general, why might a change in amino acid sequence affect protein function?
Proteins are complex molecules. Each type of protein has a unique three-dimensional shape, determined by how the protein folds up. If it does not fold up into the correct shape, it cannot carry out its function in the cell. A protein is held in its shape by bonds formed between amino acids which are spaced out along the protein molecule. If the wrong amino acid is present, the bond cannot be formed and so the protein cannot take up its correct shape and carry out its function. For example, the disease sickle cell anaemia is caused by a single incorrect amino acid in the haemoglobin molecule - a mistake which can be fatal! Read more: http://wiki.answers.com/Q/Why_would_a_change_in_amino_acid_sequence_affect_protein_function#ixzz1UGWxDG00
Then, explain why a change in amino acid sequence might affect protein function.?
A widely used concept must be know it somewhat is that "shape confer function" and each so often the function of a protein is its shape "Scaffold Proteins". this suggests, in a protein, a transformation in amino acid, might exchange its binding property with different amino acids interior the chain of polypeptide affecting the secondary and the tertiary shape. this might exchange the form of protein, this protein might desire to be an enzyme which won't be waiting to bind its substrate interior the terrific conformation, subsequently a malfunctioning protein is produced. yet another occasion is Sickle cellular Anemia sickness, this is a factor mutation which will bring about a transformation in one amino acid interior the Beta Globin protein. this might exchange the binding residences of Beta Globin protein subunit and subsequently will impression formation of hemoglobin protein. this might bring about a transformation interior the form of crimson Blood Cells which will cut back its affinity for oxygen molecules. So, this finished sickness resulted from a transformation in one amino acid in between the subunits that varieties hemoglobin, it somewhat is a protein interior the crimson Blood Cells responsible for carrying Oxygen.
Changing one amino acid within a protein could change what about protein ?
d- all can be changed.
Describe how changing one amino acid in an enzyme could affect the function of that enzyme.?
enzymes are proteins and that they are particular in action which potential one enzyme is able to accomplish only one reaction. Enzymes are denatured (do now no longer artwork) by severe temperatures (above 40 ranges celsius), and as quickly as an enzyme has been denatured you would be unable to lead them to artwork back. The optimal (superb) temperature for enzymes to artwork is 38 ranges celcius. diverse enzymes artwork superb in diverse pH, eg. Pepsin, it extremely is one in all those protease (breaks proteins) works at acidic pH of a million-2. Amylase which digests startch works interior the mouth the place pH is approximately independent. different residences of enzymes incorporate: they are inactivated by poisons, and each and each enzyme has a various shape, made precisely to in good shape one substrate ( the substance which the enzyme is going to artwork on).
Why does changing the sequence of amino acids changes the protein shape?
Actually, it can be quite difficult to change the fold of a protein through mutation. Usually mutations do either just about nothing, or they caust the protein to UNFOLD, not fold into a different shape. There was a big competition done years ago requesting that people change an all-alpha-helical protein to an all-beta-sheet protein, with a minimum number of mutations. If I remember correctly the first success occured not until half of the amino acid types were changed. Now, this is speaking just about the global 'domain' fold of a protein. Single mutations can affect local structural features of a protein while maintaining the global fold. For instance a loop may initiate with a hydrophobic amino acid that is embedded in the core of the protein. If the loop begins with a Valine (a small hydrophobic amino acid) that is replaced by a Phenylalanine (a large aromatic amino acid), the structure might be preserved, but the larger amino acid will likely be too bulky to fit into the core pocket that the valine fit snugly into, and the loop may now be more flexible due to the loss of this stabilizing feature. Sometimes these small mutations are important, sometimes not. If they are in the viscinity of a functional site (a catalytic site or a protein-protein interface site) then they may very well affect the function of the protein by disrupting it's activity. I hope this helps!