Practicing Success

Target Exam

CUET

Subject

Biology

Chapter

Molecular Basis of Inheritance

Question:

Determining the biochemical nature of genetic material and the structure of DNA was very exciting, the proposition and deciphering of genetic code were most challenging. In a very true sense, it required involvement of scientists from several disciplines – physicists, organic chemists, biochemists and geneticists.t was George Gamow, a physicist, who argued that since there are only 4 bases and if they have to code for 20 amino acids, the code should constitute a combination of bases. He suggested that in order to code for all the 20 amino acids, the code should be made up of three nucleotides. This was a very bold proposition, because a permutation combination of 43 (4 × 4 × 4) would generate 64 codons; generating many more codons than required.he codon is triplet. 61 codons code for amino acids and 3 codons do not code for any amino acids, hence they function as stop codons. Some amino acids are coded by more than one codon, hence the code is degenerate. The codon is read in mRNA in a contiguous fashion. There are no punctuations.The code is nearly universal: for example, from bacteria to human UUU would code for Phenylalanine (phe). Some exceptions to this rule have been found in mitochondrial codons, and in some protozoans. AUG has dual functions. It codes for Methionine (met) , and it also act as initiator codon. UAA, UAG, UGA are stop terminator codons.

What is the three adjacent bases in DNA molecule are called ?

Options:

Anticodon

Codon

Exon

Intron

Correct Answer:

Codon

Explanation:

A codon is a DNA or RNA sequence of three nucleotides (a trinucleotide) that forms a unit of genomic information encoding a particular amino acid or signaling the termination of protein synthesis (stop signals). There are 64 different codons: 61 specify amino acids and 3 are used as stop signals.

In the genetic code, DNA contains the instructions necessary for creating proteins essential for an organism's functions. This genetic information is transcribed into messenger RNA (mRNA), and the sequence of bases in the mRNA determines the sequence of amino acids in a protein.

The four bases in RNA—adenine (A), uracil (U), cytosine (C), and guanine (G)—combine in triplets to form codons. Each codon corresponds to a specific amino acid, with some codons also serving as stop signals to halt protein synthesis.