Uncovering the Relationship Between Genes and Proteins - ATA Scientific
Dysferlin is a protein, and "the dysferlin gene" means "the gene which contains of three, it is important for the ribosome to know how to group the nucleotides. What is the relationship between a gene and a protein? him propose an important hypothesis explaining the underlying cause of the black urine condition . Read 3 answers by scientists with 2 recommendations from their colleagues to the question asked by Suliman Abdalla.I Ali on Dec 9,
For a small polypeptidethe amino acid sequence can be determined by clipping off one amino acid at a time and identifying it. Frederick Sanger worked out a brilliant method for deducing the sequence of large polypeptides. There are several different proteolytic enzymes—enzymes that can break peptide bonds only between specific amino acids in proteins. Proteolytic enzymes can break a large protein into a number of smaller fragments, which can then be separated according to their migration speeds in a solvent on chromatographic paper.
Unit 1: The Relationship between Genes and Proteins
Because different fragments will move at different speeds in various solvents, two-dimensional chromatography can be used to enhance the separation of the fragments Figure When the paper is stained, the polypeptides appear as spots in a characteristic chromatographic pattern called the fingerprint of the protein.
Each of the spots can be cut out, and the polypeptide fragments can be washed from the paper. Because each spot contains only small polypeptides, their amino acid sequences can be easily determined. Figure Two-dimensional chromatographic fingerprinting of a polypeptide fragment mixture.
Teaching Unit 1: The Relationship between Genes and Proteins
A protein is digested by a proteolytic enzyme into fragments that are only a few amino acids long. A piece of chromatographic filter paper is then spotted with this mixture more Using different proteolytic enzymes to cleave the protein at different points, we can repeat the experiment to obtain other sets of fragments. The fragments from the different treatments overlap, because the breaks are made in different places with each treatment.
The problem of solving the overall sequence then becomes one of fitting together the small-fragment sequences—almost like solving a tricky jigsaw or crossword puzzle Figure Figure Alignment of polypeptide fragments to reconstruct an entire amino acid sequence. Different proteolytic enzymes can be used on the same protein to form different fingerprints, as shown here.
The amino acid sequence of each fragment can be determined rather more Using this elegant technique, Sanger confirmed that the sequence of amino acids as well as the amounts of the various amino acids is specific to a particular protein.
In other words, the amino acid sequence is what makes insulin insulin. Relation between gene mutations and altered proteins We now know that the change of just one amino acid is sometimes enough to alter protein function.
This was first shown in by Vernon Ingram, who studied the globular protein hemoglobin—the molecule that transports oxygen in red blood cells. These proteins fold into complicated three-dimensional structures, somewhat like molecular origami.
Because each amino acid has specific chemical characteristics, the sequence of amino acids determine the structure and shape of a protein. For example, some amino acids attract water, and others are repelled by it. Some amino acids can form weak bonds to each other, but others cannot.
Proteins that catalyze accelerate chemical reactions, for example, have "pockets," which can bind specific chemicals and make it easier for a particular reaction to occur.
Variations in the DNA code of a gene can change either the structure of a protein or when and where it is produced.
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If these variations change the protein structure, they could also change its function. For example, a single, specific mutation in hemoglobin -- the oxygen-carrying protein abundant in your red blood cells -- affects oxygen transport and is enough to cause sickle-cell anemia. Traits Variations in a gene can affect traits in several ways. Variations in proteins involved in growth and development, for example, can give rise to differences in physical features like height.