N Exam 4 Chapter 22, 23, 24/26 University of Nebraska - Linco x Gtrna structure
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N Exam 4 Chapter 22, 23, 24/26 University of Nebraska - Linco x Gtrna structure and function Cx ? C Secure ! https://mapleta.uni.edu/mapleta/modules/unproctoredTest.QuestionSheet :: Apps M McGraw-Hill Conn D ESPN D Google The Weather Channel Imported From Safari N Canvas Question 21 Essay Question (8 points) Answer should be approximately 1 to 2 paragraphs and use the relevant biochemical vocabulary to provide an answer. 8 points Protein synthesis employs tRNA molccules as cofactors in the process. The image shows the common 2-D model of a tRNA. The following questions match the letters identified in the image. OH (a) Explain what the 3' end of the tRNA is used for. Describe the chemical process that occurs at this end. (b) This loop contains an important section of RNA nucleotides. What is the name of this section and how is it used in protein synthesis? (c) The structure of a tRNA is stabilized by complement base pairing. Explain why the stems have a more C/G pairs than A/T pairs. ParanranhEont Submit Assignment Quit & Save Back Question Menu NexExplanation / Answer
Ans. #a. Aminoacyl tRNA synthetase catalyzes the addition of a specific amino acid to the 3’-OH of tRNA, the process being called the charging of amino acids. There are specific aminoacyl tRNA synthetase for each type of the 20 amino acid. Once charged with the cognate amino acid, the t-RNA carries and transfers the amino acid to the A-site of ribosome for extension of the growing polypeptide chain.
#b. The section is called anticodon loop. It facilitates the complementary binding between ribosome-bound mRNA and charged t-RNA at the A-site of ribosome. More specifically it bridges the cognate amino acids at 3’-OH of tRNA to the specific codon on mRNA at the A-site. The peptide bond synthesis between the amino acid of charged t-RNA and growing peptide chain only occurs when the anticodon (on anticodon loop) complementarily binds to the mRNA codon on A-site of ribosome.
#c. A G-C pair forms 3 H-bonds whereas an A-T pair forms only 2 H-bonds. So, greater is the number of G-C pairs, greater would be the number of intrastrand H-bonds. A greater number H-bonds would stabilize the secondary and tertiary structures more efficiently. Therefore, the stem has more G-C pairs to attain greater stability through intra-strand H-bonds.
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