Explain the meaning and significance of the following terms

Explain the meaning and significance of the following terms: (a) Decoding center in ribosome (b) open complex

Solution

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(a) Decoding center in ribosome: The ribosome is a proteo-RNA complex by nature. It contains two major subunits called the 40S and 80S subunits. These subunits have differential function in the process of translation. Specifically, the smaller subunit i.e. the 40S unit is directly involved in identification of the correct sequence complementarity between the mRNA and the tRNA. This property of 40S subunit is extremely important for optimum binding of the two nucleotides on the ribosome and thus helps in initiation of translation. The region of RNA complex of 40S subunit is thus termed as decoding centre in the ribosome.

(b) open complex: During transcription process, the DNA duplex opens up due to activity of enzyme helicase. The transcription machinery thus comes into action, binds to the appropriate strand of the DNA and thus brings about the generation of mRNA strand in appropriate direction and orientation. Thus, until transcription takes place, a portion of DNA remains opened up as the helix is released and hence, a complex of DNA, nascent mRNA, various enzymes and transcription factors is made upon the DNA. This complex is termed as open complex. This open complex is present in both eukaryotes and prokaryotes.