Gentic code

• The order of bases on DNA is called the genetic code which consists of triplets of bases,

  each triplet of bases codes for a particular amino acids and is known as a codon
• The amino acids are then joined together by peptide bonds and form a polypeptide chain. Therefore, a gene is a sequence of bases on a DNA molecule coding for a sequence of amino acids in a polypeptide chain.
• However, not all the genome codes for proteins – the non-coding sections

  of DNA are called introns and the coding regions are called exons.
• The genetic code is non-overlapping meaning that each triplet is only read once and triplets don’t share any bases
• Genetic code is also degenerate meaning that more than one triplet codes for the

  same amino acids, this reduces the phenotypic effect of mutations (which are

  mistakes in the base sequence such as base deletion, insertion or substitution).
• A change in the base sequence of DNA may alter the amino acid sequence and the

  protein therefore it can have various effects.
• The genetic code contains start and stop codons which either start or stop protein

  synthesis