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प्रश्न
Enlist the characteristics of genetic code.
Describe any three characteristics of the genetic code.
Enlist the four characteristics of the genetic code.
Write any six characteristics of genetic code.
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उत्तर
- Genetic code is a triplet code: A sequence of three consecutive bases constitutes a codon, which specifies one particular amino acid. Base sequence in a codon is always in 5’ → 3’ direction. In every living organism, the genetic code is a triplet code.
- Genetic code has distinct polarity: Genetic code shows definite polarity, i.e., direction. It is always read in 5’ → 3’ direction and not in 3’ → 5’ direction. Otherwise, the message will change, e.g., 5’ AUG 3’.
- Genetic code is non-overlapping: Code is non-overlapping, i.e., every single base is a part of only one codon. Adjacent codons do not overlap.
- Genetic code is commaless: There is no gap or punctuation mark between successive/consecutive codons.
- Genetic code has degeneracy: Usually, a single amino acid is encoded by a single codon. However, some amino acids are encoded by more than one codon. e.g., Cysteine has two codons, while isoleucine has three. This is called the degeneracy of the code. The degeneracy of the code is explained by the Wobble hypothesis. Here, the first two bases in different codons are identical, but the third one varies.
- Genetic code is universal: In most living organisms, the specific codon specifies the same amino acid. e.g., Codon AUG always specifies the amino acid methionine.
- Genetic code is non-ambiguous: The specific amino acid is encoded by a particular codon. Alternatively, two different amino acids will never be encoded by the same codon.
- Initiation codon and termination codon: AUG is always an initiation codon in any and every mRNA. AUG codes for the amino acid methionine. Out of 64 codons, three, viz., UAA, UAG, and UGA, are termination codons that terminate or stop the process of elongation of a polypeptide chain, as they do not code for any amino acid.
- Codon and anticodon: A codon is a part of DNA, e.g., AUG is a codon. It is always represented as 5’ AUG 3’. Anticodon is a part of tRNA. It is always represented as 3’ UAC 5’.
Notes
Students should refer to the answer according to their questions.
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संबंधित प्रश्न
Long Answer Question:
Justify the statement. If the answer is false, change the underlined word(s) to make the statement true
The process of translation occurs at the ribosome.
Find out the double ring compound.
Explain in short.
Transcription
Protein synthesis and cell division is accelerated by the hormone ______.
In processing of eukaryotic hnRNA, during protein synthesis what does the tailing of RNA involve?
Sequential order of nucleotides on template strand forming m-RNA synthesizing specific protein is given below. Based on it select the sequential t-RNA anticodon entering in the process of protein synthesis.
Template: TAC GAC AAC CAC TTA ATT
Select the correct option regarding the statements given below.
Statement I: In the process of transcription, the entire length of DNA is copied into RNA.
Statement II: Copying of DNA to RNA in transcription is based on complementarity base pairing.
During the post transcriptional modification, ______ process does not occur.
Given below is a stretch of DNA showing the coding strand of a structural gene of a transcription unit?
5’-ATG ACC GTA TTT TCT GTA GTG CCC GTA CTT CAG GCA TAA-3’
- Write the corresponding template strand and the mRNA strand that will be transcribed, along with its polarity.
- If GUA of the transcribed mRNA is an intron, depict the sequence involved in the formation of mRNA/the mature processed hnRNA strand.
i. In a bacterium
ii. In humans - Upon translation, how many amino acids will the resulting polypeptide have? Justify.
During transcription, the DNA strand which acts as a template is called ___A___ strand and it has ___B___ polarity.
