Define 'Genetic Code.' What are its characteristics ?

**OR**

Write explanatory note on the central dogma and central dogma reverse of molecular biology.

Question

Define 'Genetic Code.' What are its characteristics ?

**OR**

Write explanatory note on the central dogma and central dogma reverse of molecular biology.

Accepted Answer

>

> [!TLDR]
> The genetic code is the correspondence between mRNA triplet codons and amino acids; it is triplet, degenerate, unambiguous, non-overlapping, and nearly universal.
>
> **Genetic code — definition:** The genetic code refers to the set of rules that define how a sequence of nucleotide bases in mRNA (read in groups of three, called codons) specifies a particular sequence of amino acids during protein synthesis (translation). It was deciphered chiefly through the work of Har Gobind Khorana, Marshall Nirenberg and Severo Ochoa.
>
> **Characteristics of the genetic code:**
> 1. **Triplet:** A codon consists of three consecutive nucleotides. With 4 possible bases, there are 4³ = 64 possible codons, coding for 20 amino acids.
> 2. **Degenerate (redundant):** More than one codon can specify the same amino acid (e.g. leucine and serine each have 6 codons), except for methionine (AUG) and tryptophan (UGG), which each have only a single codon.
> 3. **Unambiguous:** A given codon always codes for only one specific amino acid.
> 4. **Non-overlapping and comma-less (continuous):** The code is read in a continuous sequence of triplets from a fixed starting point, without gaps between codons, and each base is part of only one codon.
> 5. **(Nearly) universal:** With minor exceptions (e.g. in some mitochondrial codes), the same codon specifies the same amino acid across nearly all organisms, from bacteria to humans.
> 6. **AUG has a dual role:** it codes for methionine, and it also serves as the **initiator (start) codon** for translation.
> 7. **Stop (nonsense/terminator) codons:** UAA, UAG and UGA do not code for any amino acid; they signal the termination of translation.
>
> **OR — Central dogma and its reverse:** …

Q.Define 'Genetic Code.' What are its characteristics ? OR Write explanatory note on the central dogma and central dogma reverse of molecular biology.

Concept understanding — Properties of the Genetic Code

Properties of the Genetic Code

Why Scientists Felt the Need to Propose a Code

Key Properties

Q.Define 'Genetic Code.' What are its characteristics ? OR Write explanatory note on the central dogma and central dogma reverse of molecular biology.

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