Chapter 14 Translation and Proteins1) Which of the following are among the major components of prokaryotic ribosomes?A) 12S rRNA, 5.8S rRNA, and proteinsB) 16S rRNA, 5.8S rRNA, and 28S rRNAC) 16S rRNA, 5S rRNA, and 23S rRNAD) lipids and carbohydratesE) 18S rRNA, 5.8S rRNA, and proteinsAnswer: CSection: 14.32) The term peptidyl transferase relates to ________.A) base additions during mRNA synthesisB) peptide bond formation during protein synthesisC) elongation factors binding to the large ribosomal subunitD) discontinuous strand replicationE) 5' capping of mRNAAnswer: BSection: 14.23) The one-gene:one-enzyme hypothesis emerged from work on which two organisms?A) E. coli and yeastB) Drosophila and humansC) Neurospora and DrosophilaD) E. coli and humansE) All of the answers listed are correct.Answer: CSection: 14.64) The β chain of adult hemoglobin is composed of 146 amino acids of a known sequence. In comparing the normal β chain with the β chain in sickle cell hemoglobin, what alteration is one likely to find?A) valine instead of glutamic acid in the sixth positionB) glutamic acid replacing valine in the first positionC) extensive amino acid substitutionsD) trinucleotide repeatsE) frameshift substitutionsAnswer: ASection: 14.71Copyright © 2012 Pearson Education, Inc.5) The primary structure of a protein is determined by ________. A) the sequence of amino acidsB) hydrogen bonds formed between the components of the peptide linkageC) a series of helical domainsD) pleated sheetsE) covalent bonds formed between fibroin residuesAnswer: ASection: 14.96) One form of posttranslational modification of a protein includes ________.A) removal of intronsB) shuffling of exonsC) removal or modification of terminal amino acidsD) removal of exonsE) self-splicingAnswer: CSection: 14.107) Which protein class directly controls many of the metabolic reactions within a cell?A) structural proteinsB) repressor proteinsC) operator proteinsD) enzymesE) hydrophilic proteinsAnswer: DSection: 14.118) The secondary structure of a protein includes ________.A) gamma and deltaB) alpha and gammaC) α-helix and β-pleated sheetD) hydrophobic clustersE) disulfide bridgesAnswer: CSection: 14.99) Side groups of amino acids are typically classified under which of the following?A) polar, nonpolarB) linear, circularC) alpha, omegaD) long, shortE) primary, secondaryAnswer: ASection: 14.92Copyright © 2012 Pearson Education, Inc.10) A protein is 300 amino acids long. Which of the following could be the number of nucleotides in the section of DNA that codes for this protein? (Remember: DNA is double-stranded.)A) 3B) 100C) 300D) 500E) 1800Answer: ESection: 14.1, 14.211) By their experimentation using the Neurospora fungus, Beadle and Tatum were able to propose the far-reaching hypothesis that ________.A) prototrophs will grow only if provided with nutritional supplementsB) several different enzymes may be involved in the same step in a biochemicalpathwayC) the role of a specific gene is to produce a specific enzymeD) genetic recombination occurred in NeurosporaE) more than one codon can specify a given amino acidAnswer: CSection: 14.612) A short segment of an mRNA molecule is shown below. The polypeptide it codes for is also shown:5'-AUGGUGCUGAAG : methionine-valine-leucine-lysineAssume that a mutation in the DNA occurs so that the fourth base (counting from the 5' end) of the messenger RNA now reads A rather than G. What sequence of amino acids will the mRNA now code for? (You do not need a copy of the genetic code to answer the question.)A) methionine-valine-leucine-lysineB) methionine-lysine-leucine-lysineC) methionine-leucine-leucine-lysineD) methionine-valine-methionine-lysineE) methionine-methionine-leucine-lysineAnswer: ESection: 14.1, 14.213) During translation, which triplets signal chain termination?Answer: UAA, UGA, UAGSection: 14.13Copyright © 2012 Pearson Education, Inc.14) Describe each of the following parameters that relate to the structure and function of tRNA:(a)four functional domains(b)Wobble hypothesisAnswer: (a) The four functional domains are amino acid attachment site, ribosome binding site, anticodon, and aminoacyl synthetase binding site.(b) The Wobble hypothesis states that the first two positions of the codon are precise in their complementary relationships. However, the third position is less specific.Section: 14.115) Draw and label the spatial and polarity relationships among the following translational components: ribosome (small and large subunits), growing polypeptide chains, amino acid attachment to tRNA, mRNA, codon, and anticodon. Answer: Section: 14.24Copyright © 2012 Pearson Education, Inc.16) The following drawing represents simultaneous transcription and translation in E. coli.Answer the questions below the drawing. The direction of the RNA polymerase is given by the arrow.(a) Is the letter A nearer the 5' or the 3' end of the molecule? ________(b) Is the letter B nearer the 5' or the 3' end of the molecule? ________(c)Is the letter C nearer the 5' or the 3' end of the tRNA molecule? ________(d) What is the "S" value for the large rRNA that is closest to the letter D? ________(e) Which terminus (N or C) of the growing polypeptide chain is nearer to the letter E? ________Answer: (a) 3', (b) 5', (c) 3', (d) 23S, (e) NSection: 14.217) Knowing that the base sequence of any given messenger RNA is responsible for precisely ordering the amino acids in a respective protein, present two mechanisms by which intrinsic properties of mRNA may regulate the "net output" of a given gene.Answer: (a) Final output of a given gene may be influenced by the stability of an mRNA, and stability of an mRNA is determined in part by its base content and sequence. (b) Differential splicing of mRNA (actually mRNA precursors) can influence how much of a given product will be made from a gene.Section: 14.1, 14.218) What are polyribosomes?Answer: clusters of ribosomes held together by an mRNASection: 14.25Copyright © 2012 Pearson Education, Inc.19) Below are several phenomena relating to protein structure. Clearly describe each phenomenon, the conditions under which each occurs, and the probable influence each has on protein structure. (a) hydrophobic interactions(b) hydrogen bonds(c) disulfide bridgesAnswer: (a) Hydrophobic interactions: These are nonpolar side chains of amino acids that tend to associate to form hydrophobic clusters usually away from the