Concept explainers
REFLECT AND APPLY A sample of a peptide of unknown sequence was treated with trypsin; another sample of the same peptide was treated with chymotrypsin. The sequences (N-terminal to C-terminal) of the smaller peptides produced by trypsin digestion were as follows:
The sequences of the smaller peptides produced by chymotrypsin digestion were as follows:
Deduce the sequence of the original peptide.
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Chapter 5 Solutions
Biochemistry
- REFLECT AND APPLY A sample of an unknown peptide was divided into two aliquots. One aliquot was treated with trypsin; the other was treated with cyanogen bromide. Given the following sequences (N-terminal to C-terminal) of the resulting fragments, deduce the sequence of the original peptide. Trypsin treatment AsnThrTrpMetIleLysGlyTyrMetGlnPheValLeuGlyMetSerArg Cyanogen bromide treatment GlnPheValLeuGlyMetIleLysGlyTyrMetSerArgAsnThrTrpMetarrow_forwardREFLECT AND APPLY Explain why a 50S ribosomal subunit and a 30S ribosomal subunit combine to form a 70S subunit, instead of an 80S subunit.arrow_forwardREFLECT AND APPLY You are studying with a friend who says that the hydrogen-bonded portions of tRNA play no important role in its function. What is your reply?arrow_forward
- REFLECT AND APPLY Why is a trimming process important in converting precursors of tRNA and rRNA to the active forms?arrow_forwardREFLECT AND APPLY List three molecular changes that take place in the processing of eukaryotic mRNA.arrow_forwardREFLECT AND APPLY In prokaryotic protein synthesis, N-formylmethionine (fmet) is the first amino acid incorporated, whereas (normal) methionine is incorporated in eukaryotes. The same codon (AUG) serves both. What prevents methionine from being inserted into the beginning and N-formylmethionine in the interior?arrow_forward
- REFLECT AND APPLY Outline a mechanism by which RNA can catalyze its own self-splicing.arrow_forwardREFLECT AND APPLY You are in the process of determining the amino acid sequence of a peptide. After trypsin digestion followed by the Edman degradation, you see the following peptide fragments: LeuGlyArgGlySerPheTyrAsnHisSerGluAspMetCysLysThrTyrGluValCysMetHis What is abnormal concerning these results? What might have been the problem that caused it?arrow_forwardREFLECT AND APPLY (a) How many activation cycles are needed for a protein with 150 amino acids? (b) How many initiation cycles are needed for a protein with 150 amino acids? (c) How many elongation cycles are needed for a protein with 150 amino acids? (d) How many termination cycles are needed for a protein with 150 amino acids?arrow_forward
- REFLECT AND APPLY The structures of tRNAs contain several unusual bases in addition to the typical four. Suggest a function for the unusual bases.arrow_forwardREFLECT AND APPLY Why do amino acids other than methionine occur in the N-terminal position of proteins from eukaryotes?arrow_forwardREFLECT AND APPLY Would you expect tRNA or mRNA to be more extensively hydrogen bonded? Why?arrow_forward
- BiochemistryBiochemistryISBN:9781305961135Author:Mary K. Campbell, Shawn O. Farrell, Owen M. McDougalPublisher:Cengage Learning