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How would this mutation affect attenuation of the tryptophan operon? Explain your answer.
Would formation of the
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Chapter 12 Solutions
Pearson eText Genetic Analysis: An Integrated Approach -- Instant Access (Pearson+)
- What is the primary difference betwee class I and class II aminoacyl-tRNA synthetases. a. Class I synthetases acylate the terminal 2’ hydroxyl group of tRNAs; Class II synthetases acylate the terminal 3’ hydroxyl group of tRNAs. b. Class I synthetases acylate the terminal 3’ hydroxyl group of tRNAs; Class II synthetases acylate the terminal 2’ hydroxyl group of tRNAs. c. Class I synthetases acylate tRNAs with hydrophobic amino acids; Class II synthetases acylate tRNAs with polar amino acids. d. Class I synthetases acylate tRNAs with polar amino acids; Class II synthetases acylate tRNAs with hydrophobic amino acids.arrow_forwardExamine the tRNA in Figure 15.14. What do you think would be the potential effect of a mutation in the part of the tRNA gene that encodes (a) the acceptor stem; (b) the anticodon; (c) one of the red nucleotide positions?arrow_forwardDNA in human mitochondria encodes 22 different tRNA molecules. However, 32 different tRNA molecules are required for translation of proteins within mitochondria. Explain.arrow_forward
- Many clinically relevant mitochondrial diseases are caused by mutations in mitochondrial genes affecting tRNAs. For example, one form of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes) is caused by a point mutation in the gene encoding the mitochondrial tRNA whose anticodon recognizes the codons 5' UUA and 5' UUG. The mutation makes the aminoacylation of this tRNA inefficient. a. The rate of synthesis of most mitochondrial proteins is either unaffected or slightly decreased in MELAS cells, but one mitochondrial protein called NAD6 is synthesized at only 10% of the normal rate. How is it possible that the translation of this single mitochondrial protein might be affected specifically?arrow_forwardA certain ochre suppressor inserts glutamine in response to the ochre codon. What is the most likely change in the anticodon of a tRNAGln that created this suppressor strain?arrow_forwardIn this chapter you were introduced to nonsense suppressor mutations in tRNA genes. However, suppressormutations also occur in protein-coding genes. Using thetertiary structure of the β subunit of hemoglobin shownin Figure 9-3(c), explain in structural terms how a mutation could cause the loss of globin protein function. Nowexplain how a mutation at a second site in the same protein could suppress this mutation and lead to a normalor near-normal protein.arrow_forward
- Describe the two sequential reactions that occur in the activesite of aminoacyl-tRNA synthetases.arrow_forwardThe covalent attachment of an amino acid to a tRNA is an endergonic reaction. In other words, it requires an input of energy for the reaction to proceed. Where does the energy come from to attach amino acids to tRNA molecules?arrow_forwardConsider the now dominant variant of the SARS-CoV-2 called the D614G mutation: a) The mutation changes an Aspartate (D, Asp) to a Glycine (G, Gly) at nucleotide position 614 (that’s why it’s called the D614G mutant) in the S1 subunit of the Spike protein. Using only the information above and a codon table, what are the mRNA codon sequences of the 2019-dominant and 2020-dominant Spike proteins? Note the figure above is not needed toanswer the question. Report in 5’ to 3' orientation __________________________________________ b) What type of substitution is this? In your answer, address the following: • The expected substitution in base sequence (e.g., A à C)• If the mutation is synonymous, nonsynonymous, or a frameshift• If the mutation is a transition or a transversion c) The mutation increases infectivity by reducing the stability of the Spike protein such that it can remain in the open conformation more often. The open conformation increases the chances of binding to the host ACE2…arrow_forward
- Many blood clotting proteins undergo a post-translational modification in which specific glutamic acid residues (Glu) in the protein are converted to gamma-carboxyglutamic acid residues (Gla). See reaction scheme below. An example is the blood clotting protein Factor IX, which has 12 Glu in its N-terminus converted to Gla. This modification gives Factor IX the ability to bind calcium and phospholipid membranes. Bacteria do not have the enzyme required to convert Glu to Gla and therefore Factor IX proteins expressed in bacteria would not have the proper modifications. How might you engineer the translational apparatus of a bacterial cell line so that it produces Factor IX with Gla in the appropriate positions. How would you ensure that only the 12 Glu in Factor IX that are normally converted to Gla and not just all Glu (Limit 5-6 senetnces)?arrow_forwardSeveral experiments were conducted to obtain information about how the eukaryotic ribosomerecognizes the AUG start codon. In one experiment, the gene that encodes the methionine initiatortRNA (tRNA,Met) was identified and changed. Specifically, the nucleotides that specify the anticodonon the tRNA,Met were mutated so that the anticodon in the tRNA was 5'-CCA-3'. When thismutated gene was introduced into a eukaryotic cell protein synthesis occurred, but the proteinsproduced were abnormal. Some of these proteins contained extra amino acids and others containedfewer amino acids than normal. a.) What is the normal anticodon for tRNA,Met? Show how this normal anticodon would interact with the codon for methionine in the mRNA. b.) What codon does the mutant anticodon bind? What amino acid is incorporated into the polypeptide chain? Show the interaction between the mutant anticodon and the amino acid codon and finally, What do the results described above indicate about how the ribosome…arrow_forwardSeveral experiments were conducted to obtain information about how the eukaryotic ribosomerecognizes the AUG start codon. In one experiment, the gene that encodes the methionine initiatortRNA (tRNA,Met) was identified and changed. Specifically, the nucleotides that specify the anticodonon the tRNA,Met were mutated so that the anticodon in the tRNA was 5'-CCA-3'. When thismutated gene was introduced into a eukaryotic cell protein synthesis occurred, but the proteinsproduced were abnormal. Some of these proteins contained extra amino acids and others containedfewer amino acids than normal. Explain why some of the proteins produced contained extra amino acids while otherscontained fewer amino acids than normal? e. If the same experiment had been conducted in bacterial cells, what results would youexpect? Explain.arrow_forward
- Biology Today and Tomorrow without Physiology (Mi...BiologyISBN:9781305117396Author:Cecie Starr, Christine Evers, Lisa StarrPublisher:Cengage Learning