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CELL AND DEVELOPMENTAL BIOLOGY PRESENTATION. DNA and genetic code are correlative terms. Genetic code: sequence of nucleotides in deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) determines specific amino acid sequence in the synthesis of proteins
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DNA and genetic code are correlative terms. Genetic code: sequence of nucleotides in deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) determines specific amino acid sequence in the synthesis of proteins It consists of 64 triplets of nucleotides, called codons. Most of the 20 amino acids can be encoded for by more than one codondegenerate code Codons that specify the same amino acid are called synonyms. DNA and GENETIC CODE
Although the genetic information is based in the sequence of nucleotides along the DNA chain, DNA is not the direct template for protein synthesis.However, a messenger RNA molecule is synthesized from the DNA directs the information of the protein. In addition, other kinds of RNA molecules, such as transfer RNA (tRNA) and ribosomal RNA (rRNA) have equallya significant role in protein synthesis. Gene expression in normal cells:DNAtranscription RNAtranslation Protein
DNA Structure • DNA is composed nucleotides arranged in a double helix formation. • Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base (A,T,C,G) attached to the sugar, and a phosphate group. • The base sequence is written in the 5’ to 3’ direction. • Guanine is paired with cytosine and adenine with thymine (G C, A T) and are held together by specific hydrogen bonds.
DNA Replication • DNA is replicated in such a way that each of the two daughter molecules is identical to the parent molecule. • The hydrogen bonds between the complementary bases on the two strands of the parent molecule break and the strands unwind. Using as building bricks nucleotides present in the nucleus, each strand directs the synthesis of a new complementary to itself. • Replication is initiated, controlled, and stopped by means of polymerase enzymes. • DNA replication. The double helix is unwound and • each strand acts as a template. Bases are matched • to synthesize the new partner strands. http://en.wikipedia.org/wiki/DNA_replication
IMPORTANCE OF DNA DNAIS THE BIOCHEMICAL BASIS OF HEREDITY AND IS NEARLY UNIVERSAL IN ALL ORGANISMS
BIBLIOGRAFY: http://www.wikipedia.org/ http://science.jrank.org/pages/2001/Deoxyribonucleic-Acid-DNA-Structure.html