Genetic code
- 1. • Presentation on Genetic Code Institute of Agriculture Sciences Presented by:- UTTAM KUMAR PATEL B.Sc. Agriculture (1st Year)
- 2. What is Genetic Code ? • The Genetic Code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins by living cells. • The letters A, G, T and C correspond to the nucleotides found in DNA. They are organized into codons
- 3. Codons & Its Types Genetic code is a Dictionary consists of “Genetic words” called CODONS. • Each codon consists of three bases (triplet). • There are 64 codons. • 61 codons code for 20 amino acids found in protein. • 3 codons do not code for any amino acids.
- 4. Sense codon: The codon that code for amino acid are called sense codon. Signal codon: Those codons that code for signal during protein synthesis are called signal codons. For Example: AUG, UAA, UAG & UGA. There are Two types of signal codons. • Terminating Codons • UAA, UAG & UGA are termination codons or non-sense codons & are often referred to as amber, ochre & opal codons. • Initiating codon • AUG is the initiation codon. It codes for the first amino acid in all proteins. • At the starting point it codes for methionine in eukaryotes & formyl methionine in prokaryotes. Types
- 5. Anticodon • The base sequence of tRNA which pairs with codon of mRNA during translation is called anticodon. • The codon of the mRNA is recognized by the anticodon of tRNA. • They pair with each other in antiparallel direction (5’- 3’ of mRNA with 3’- 5’of tRNA).
- 6. Properties of Genetic Code UNIVERSALITY • The genetic code is universal. • AUA is the codon for methionine in mitochondria.The same codon (AUA) codes for isoleucine in cytoplasm.With some exceptions noted the genetic code is universal. NON- OVERLAPPING • One base cannot participate in the formation of more than one codon. • This means that the code is non- overlapping.
- 7. DEGENERACY • There are more than one codon for one amino acid. • This is called degeneracy of genetic code.
- 8. Wobble Hypothesis • Francis Crick proposed the wobble hypothesis in 1966 to explain the pattern of degeneracy. • Though there are 61 codons coding for amino acids, we do not need 61 types of tRNA. • The 3rd nucleotide in the anticodon is often less important than the first two (binds weakly / not specific). • The third nucleotide is in the “wobble” position
- 9. • Uttam Kumar Patel E-mail:-uttampatel494@gmail.com