Genetics: From Genes to Genomes
6th Edition
ISBN: 9781259700903
Author: Leland Hartwell Dr., Michael L. Goldberg Professor Dr., Janice Fischer, Leroy Hood Dr.
Publisher: McGraw-Hill Education
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Chapter 15, Problem 26P
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? |
| b. | Why might the decreased translation of this one protein be responsible for the pathological condition? |
| c. | Researchers are currently investigating ways to treat the symptoms of MELAS patients. One strategy involves a change to a nuclear gene. What nuclear gene might the investigators be targeting? (Assume that you can make any desired change to nuclear genes; we will describe methods to alter genomes in Chapter 18.) |
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Chapter 15 Solutions
Genetics: From Genes to Genomes
Ch. 15 - Match each numbered item with the most closely...Ch. 15 - Assuming human cells have on average 1000...Ch. 15 - Reverse translation is a term given to the process...Ch. 15 - The human nuclear genome encodes tRNAs with 32...Ch. 15 - The human mitochondrial genome includes no genes...Ch. 15 - How do you know if the halibut you purchased at...Ch. 15 - Is each of these statements true of chloroplast or...Ch. 15 - Suppose you are characterizing the DNA of a...Ch. 15 - An example of a gene-targeting DNA plasmid vector...Ch. 15 - Which of the following characteristics of...
Ch. 15 - The Saccharomyces cerevisiae nuclear gene ARG8...Ch. 15 - The so-called hypervariable regions HV1 and HV2 of...Ch. 15 - Suppose a new mutation arises in a mitochondrial...Ch. 15 - Describe at least two ways in which the...Ch. 15 - Why are severe mitochondrial or chloroplast gene...Ch. 15 - Suppose you are examining a newly found plant...Ch. 15 - A form of male sterility in corn is inherited...Ch. 15 - Plant breeders have long appreciated the...Ch. 15 - A mutant haploid strain of Saccharomyces...Ch. 15 - Prob. 20PCh. 15 - What characteristics in a human pedigree suggest a...Ch. 15 - The first person in the family represented by the...Ch. 15 - In 1988, neurologists in Australia reported the...Ch. 15 - If you were a genetic counselor and had a patient...Ch. 15 - Kearns-Sayre syndrome KSS, Pearson syndrome, and...Ch. 15 - Many clinically relevant mitochondrial diseases...Ch. 15 - Leigh syndrome is characterized by psychomotor...Ch. 15 - All mutations in mitochondrial genes ultimately...Ch. 15 - How could researchers have determined that the...
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- Describe the two sequential reactions that occur in the activesite of aminoacyl-tRNA synthetases.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_forwardWhen the amino acid sequences of insulin isolated from different organisms were determined, differences were noted. For example, alanine was substituted for threonine, serine for glycine, and valine for isoleucine at corresponding positions in the protein. List the single-base changes that could occur in codons of the genetic code to produce these amino acid changes.arrow_forward
- The charging of a tRNA with an amino acid can be represented by the following equation:amino acid + tRNA + ATP → aminoacyl-tRNA + AMP + PPI where PPI is pyrophosphate (see figure 3–40). in the aminoacyl-tRNA, the amino acid and tRNA are linked with a high-energy covalent bond; a large portion of the energy derived from the hydrolysis of ATP is thus stored in this bond and is available to drive peptide bond formation at the later stages of protein synthesis. the free-energy change of the charging reaction shown in the equation is close to zero and therefore would not be expected to favor attachment of the amino acid to tRNA. Can you suggest a further step that could drive the reaction to completion?arrow_forwardOrotic aciduria is a rare hereditary disorder due to deficient orotate phosphoribosyltransferase and orotidine-5'-decarboxylase activities that are encoded by Uridylate (UMP) synthetase gene in de novo pyrimidine biosynthesis. The characteristic of this disorder is excessive excretion of orotic acid in urine. A mutation of UMP synthetase gene has been identified as R96G (at amino acid position 96, Arginine is changed to Glycine). In orotic aciduria, predict the consequences of deficient UMP synthetase by identifying which downstream enzyme missing its action. One of important molecules to be derived from pyrimidine biosynthesis is deoxycytidine triphosphate (dCTP) for DNA replication and repair. How is dCTP synthesized, include what enzymes and important intermediates in the pathway? 3. As thymidine triphosphate (dTTP) is needed for DNA replication and repair, what enzymes and intermediates are required to get dTTParrow_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
- Explain post-translational modification of proteins in general with the types of reactions. Provide some examples of proteins that undergo post-translational modification. What are the protein targets, the type of reaction, and purpose or functions of this post-translational modification, then look up other resources to find other functions of lysyl-tRNA synthetase and explainarrow_forwardMetabolic syndrome is a genetic disorder with symptoms of hypertension, elevated blood cholesterol concentrations, and lower-than-normal blood magnesium concentrations. This syndrome is caused by a mutation in mitochondrial DNA (mtDNA) in which a thymine nucleotide is replaced by a cytosine nucleotide. Which of the following identifies the mutated mtDNA and the corresponding mRNA and tRNA produced in a person with metabolic syndrome if the normal mtDNA triplet is TCG? Select one: a. Mutated mtDNA: CCG mRNA: GGC tRNA: GGC b. Mutated mtDNA: TCG mRNA: UGC tRNA: ACG c. Mutated mtDNA: CCG mRNA: GGC tRNA: CCG d. Mutated mtDNA: TTG mRNA: AAC tRNA: UUCarrow_forwardIs the Aminoacyl tRNA synthetases in human cells specialized or non specialized? Explain.arrow_forward
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