Write an essay on Genetic code.
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Solution and Explanation
Step 1: Definition.
The genetic code is the set of rules by which the sequence of nucleotides in DNA or mRNA is translated into the sequence of amino acids in proteins. Codons (triplets of nucleotides) specify particular amino acids.
Step 2: Properties of the genetic code.
\begin{enumerate}
\item Triplet code: Each codon has 3 nucleotides.
\item Unambiguous: One codon codes for only one amino acid.
\item Degenerate: A single amino acid may be coded by more than one codon (e.g., leucine).
\item Universal: Same code is used by nearly all organisms (exceptions in mitochondria).
\item Comma-less: Codons are read continuously without gaps.
\item Start codon: AUG (codes for methionine) initiates translation.
\item Stop codons: UAA, UAG, UGA terminate translation.
\end{enumerate}
Step 3: Importance.
\[\begin{array}{rl} \bullet & \text{Ensures accurate protein synthesis.} \\ \bullet & \text{Universal nature supports the theory of common ancestry.} \\ \bullet & \text{Degeneracy reduces the effect of mutations (silent mutations possible).} \\ \end{array}\]
Step 4: Conclusion.
The genetic code is a precise, universal language of life that ensures transfer of information from DNA to proteins, sustaining all forms of life.
Top Questions on Molecular Basis of Inheritance
Student to attempt either option-(A) or (B):
(A) Write the features a molecule should have to act as a genetic material. In the light of the above features, evaluate and justify the suitability of the molecule that is preferred as an ideal genetic material.
OR
(B) Differentiate between the following:- [(i)] Polygenic Inheritance and Pleiotropy
- [(ii)] Dominance, Codominance and Incomplete dominance
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Study the given below single strand of deoxyribonucleic acid depicted in the form of a “stick” diagram with 5′ – 3′ end directionality, sugars as vertical lines and bases as single letter abbreviations and answer the questions that follow.
Name the covalent bonds depicted as (a) and (b) in the form of slanting lines in the diagram.
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