MMSC 490- Compilation of Exam 3 Quizzes-Solved

MMSC 490- Compilation of Exam 3 Quizzes-Solved Aminoacyl tRNA synthetases are enzymes that connect amino acids while they are held in place on ribosomes by transfer RNAs. synthesize transfer RNAs. attach amino acids to specific transfer RNAs. attach the terminal CCA sequence to transfer RNAs. - Answer ️️ -attach amino acids to specific transfer RNAs. E. coli contains about .................... different tRNAs that code for .................... different amino acids. 62; 20 40; 20 62; 40 50; 20 - Answer ️️ -40; 20 Which of the following is not a common lipid modification to proteins? Glycosylation N-myristoylation GPI anchor addition Prenylation - Answer ️️ -Glycosylation The formation of peptide bonds is catalyzed by which portion of the bacterial ribosome? Proteins of the large subunit 23S rRNA 16S rRNA Proteins of the small subunit - Answer ️️ -23S rRNA In translation, mRNAs are read in the .................... direction, and polypeptide chains are synthesized from the .................... ends. 5ʹ to 3ʹ; carboxyl to the amino 3ʹ to 5ʹ; carboxyl to the amino 3ʹ to 5ʹ; amino to the carboxyl 5ʹ to 3ʹ; amino to the carboxyl - Answer ️️ -5ʹ to 3ʹ; amino to the carboxyl During translation, the codons on the mRNA are recognized by complementary base pairing to the anticodon on the ribosome. small cytoplasmic RNA. transfer RNA. aminoacyl tRNA synthetase. - Answer ️️ -transfer RNA. Translation of mRNAs starts at the 5ʹ end of the mRNA. the 3ʹ end of the mRNA. a site downstream of a 5ʹ untranslated region. a site downstream of a 3ʹ untranslated region. - Answer ️️ -Correct! a site downstream of a 5ʹ untranslated region. Eukaryotic ribosomes recognize and initially bind to what structure on the mRNA? A Shine-Dalgarno sequence A CCAAT sequence The 7-methylguanosine cap A TATA sequence - Answer ️️ -The 7-methylguanosine cap The first step in the initiation of protein synthesis is the binding of .................... to the .................... . initiation factors; small ribosomal subunit the initiator tRNA; initiation codon initiation factors; initiation codon the small ribosomal subunit; initiation codon - Answer ️️ -initiation factors; small ribosomal subunit The factor that escorts the amionacyl tRNA to the eukaryotic ribosome and then releases it with GTP hydrolysis following the correct codon-anticodon base pairing is eRF-1. eIF-1. eEF-1. eIF-2. - Answer ️️ -eEF-1. The first amino acid that initiates the eukaryotic polypeptide is N-formylmethionine. methionine. any amino acid. glutamine. - Answer ️️ -methionine. In translation, mRNAs are read in the .................... direction, and polypeptide chains are synthesized from the .................... ends. 5ʹ to 3ʹ; amino to the carboxyl 3ʹ to 5ʹ; amino to the carboxyl 3ʹ to 5ʹ; carboxyl to the amino 5ʹ to 3ʹ; carboxyl to the amino - Answer ️️ -5ʹ to 3ʹ; amino to the carboxyl The amount of a protein in a cell is regulated by the rate of transcription of its gene. All of the above translation of its mRNA. degradation of the protein. - Answer ️️ -All of the above Oocytes store mRNAs with .................... and activate them by .................... . bound siRNA; removing the siRNA long poly-A tails; shortening the tails short poly-A tails; lengthening the tails no cap; addition of a cap - Answer ️️ -short poly-A tails; lengthening the tails The correctly folded three-dimensional configuration of a protein is determined primarily by the primary sequence of its amino acids. pathway by which it folds. sequence of nucleotides of its gene. chaperones with which it interacts. - Answer ️️ -primary sequence of its amino acids. Proteins that facilitate the folding of other proteins are called chaperones. binding proteins. escorts. foldases. - Answer ️️ -chaperones. Many chaperones are called heat-shock proteins because they cause fever in mammals. denature at high temperatures. are expressed at higher levels after a heat shock than at normal growth conditions. misfold during a heat shock. - Answer ️️ -are expressed at higher levels after a heat shock than at normal growth conditions. A signal peptidase removes a signal sequence from a polypeptide chain after it passes through a channel into the rough ER. removes the initial methionine from a polypeptide chain. attaches an acetyl group to the 5′ end of a polypeptide after removal of the initial methionine. attaches a signal sequence to a growing polypeptide chain bef