Biology : PU-CET (U.G) 2015 Panjab University Entrance Exam With Answers

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32.

The Two Subunits Of 70 S Ribosomes Are :

A: 50 S And 30 S
B: 45 S And 25 S
C: 50 S And 20 S
D: 40 S And 30 S

The answer is: A

Explanation

The two subunits of 70 S ribosomes are "50 S and 30 S". 70 S ribosomes are found in prokaryotic cells and are composed of two subunits: the 50 S subunit and the 30 S subunit. The 50 S subunit is the larger of the two and contains the peptidyl transferase enzyme, which is responsible for the formation of peptide bonds between amino acids during protein synthesis. The 30 S subunit contains the decoding center, which ensures the correct reading of the genetic code during translation.

The two subunits of the ribosome come together during protein synthesis, with the mRNA molecule being held in between them. The ribosome reads the genetic code on the mRNA and uses this information to synthesize a protein by linking together amino acids in the correct sequence. Once the protein is complete, the two subunits of the ribosome dissociate from each other and the mRNA molecule, ready to participate in another round of protein synthesis.