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Molecular basis of Inheritance — BIOLOGY STD 12 Science — Question

Rajasthan BoardEnglish MediumSTD 12 ScienceBIOLOGYMolecular basis of Inheritance4 Marks
Question
Following are the features of genetic codes. What does each one indicate?
Stop codon, Unambigous codon, degenerate codon, universal codon.###What do you understand by genetic code? Describe the types and characteristics of genetic code in detail.###What is Genetic code and give detail about them?###Write about characteristics and properties of Genetic code.
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Answer

Genetic Code : During replication and transcription a nucleic acid was copied to form another nucleic acid. Hence these processes are easy to conceptualize on the basis of complementarily. The process of translation required transfer of genetic information from a polymer of nucleotides to a polymer of amino acid.
Characteristics :
(a) Commaless : Genetic code is commaless. This means that the arrangement of triplet codons on m-RNA is one after other without a gap.
(b) Non-ambiguous nature : Each codon specifies a particular amino acid. The only exception is AUG which codes for methionine and GUG and codes for valine. But in the absence of AUG, GUG can also code methionine.
(c) Degenerate nature : There are 61 codons for 20 amino acids. But some amino acids are coded by more than one codon. Hence it is said to be degenerated. e.g. GGG, GGA, GGC and GGU all GGU all code for glycine.
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(d) Polarity : Genetic code could be read only in 5'-3' direction on m-RNA. This polarity is the important aspect of the genetic code. It also has start and stop signals. Start or initiation codon is AUG while UAG, UAA, UGA are the stop or termination codes.
(e) Universality : Genetic code is universal for all the organisms from simple bacteria to complex organisms.

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