Page 182 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

• Ribosomes are composed of rRNA and protein. rRNA is a major constituent

of ribosomes, composing up to about 60% of the ribosome by mass and

providing the location where the mRNA binds.

• The rRNA ensures the proper alignment of the mRNA, tRNA, and the

ribosomes

• The rRNA also has an enzymatic activity (peptidyl transferase) and catalyzes

the formation of the peptide bonds between two aligned amino acids during

protein synthesis

Transfer RNA (tRNA)

• tRNA is the smallest of the 3 types of RNA having about 75-95 nucleotides.

tRNAs are an essential component of translation, where their main function

is the transfer of amino acids during protein synthesis.

• Each of the 20 amino acids has a specific tRNA that binds with it and

transfers it to the growing polypeptide chain.

• It is the base pairing between the tRNA and mRNA that allows for the

correct amino acid to be inserted in the polypeptide chain being synthesized

General Microbiology & Immunology (PM 401) theoretical handbook Page 171