why is the sequence of bases in dna important
DNA, Enzymes and Energy
Most of our energy comes from the process of aerobic respiration, which takes place inside the mitochondria of cells. Mitochondria are oval structures with a folded inner membrane. They occur in large numbers inside muscle cells and liver cells, where large amounts of energy are needed. The mitochondria hold a large number of different enzymes which are responsible for different stages of respiration. Enzymes are soluble protein molecules that can speed up chemical reactions in cells. Like all proteins they consist of a string of different amino acid sub units. The amino acids must occur in the correct sequence for the enzyme to work. This sequence is controlled by the genetic code for the protein. These genetic codes are held in DNA molecules. chromosome One of the rod shaped bodies found in the nucleus of cells that contain genetic information (DNA).
Each DNA molecule consists of two twisted strands of bases that form a shape called a double helix. The two strands are held together by bonds between pairs of bases. When a cell grows and divides into two, it first has to make a duplicate copy of each DNA molecule. This is done by the bonds breaking between the two strands, the strands unwinding, and then new bases joining each old strand to make new strands. If A occurs in one strand of a DNA molecule it will form a bond with T in the other strand. C and G will also only bond with each other. In this way it's possible to predict the order of bases on the other strand if the bases on one strand are known.
The sequence of bases in one section (gene) of a DNA molecule controls the sequence of amino acids in one protein molecule. Each amino acid has its own code of three bases. Every time the same sequence of three bases occurs in the DNA molecule, the same amino acid is added to make up the protein. When a protein is being made, the two strands of the double helix unzip, so that the base sequence can be read. The amino acids used to make up new proteins are absorbed from food in the digestive system. It's possible for the liver to make more of a particular amino acid if needed in a process called transamination. Biology, Eighth Edition (Raven) Why does each base in DNA have a complementary base? Complementary bases are a key feature of DNA structure.
Adenine and thymine are complementary to one another as are guanine and cytosine. There are two important reasons why DNA is composed of complementary bases. The first is that only with complementary bases can the two strands of DNA have complementary sequences. Without the complementary sequences DNA replication as we know it would be impossible. The second reason is that the pairs of bases are complementary because their chemical structure allows for strong hydrogen bonding and they fit together well. The strong association between complementary bases makes DNA a stable molecule and aids in the detection of errors in DNA synthesis. View the animation below, then complete the quiz to test your knowledge of the concept.
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