ompleted and the m-RNA to be released.DNA can replicate prior to mitotic division. This process is called semiconservative, meaning that each daughter duplex contains one parental and a complimentary replicated chain. For DNA to replicate, it must first be unwound. An enzyme called helicase, using ATP as an energy source does this. The helicase helps this in process by breaking the weak hydrogen bonds between nitrogenous bases. While unwinding, the strands can become tangled and knotted. This problem is solved by an enzyme called gyrase which can make transient breaks in the strand relieving tension and then rejoins the ends. DNA replication occurs in a partially unwound are where some of the duplex region is still present, known as the replication fork. For DNA synthesis, all four nucleotides must be present. The existing DNA strands serve as templates, which dictate the nucleotide sequence of the new strand. DNA has the capacity to determine the sequences of specific proteins. The proteins are composed of amino acids; of which there are twenty types. Since there are only four types of nucleotides to "blueprint", DNA uses combinations of three nucleotides to form codons. Each gene has its own amount and series of codons, depending on the protein. There are sixty-four codons each having its own meaning. The only codon that has a double meaning is AUG. This codon symbolizes the amino acid metheonine and also signals where the polypeptide synthesis should start.Translation is the process where the amino acid sequence is derived from m-RNA. The function of t-RNA is to serve as a transporter for amino acids and an intermediate between m-RNA codons and their corresponding amino acids. Transfer RNA have anticodons which make them correspond to the codons of m-RNA. These t-RNA, that is with the help of an enzyme called aminoacyl t-RNA synthetase, carry the proper amino acids to the proper position in the m-RNA chain. When an...
