Concept explainers
Two different mutations are identified in a haploid strain of yeast. The first prevents the synthesis of adenine by a nonsense mutation of the
Do you consider the first mutation to be a forward mutation or a reversion? Why?
Do you consider the second mutation to be a forward mutation or a reversion? Why?
Assuming there are no other mutations in the genome, will this double
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Chapter 11 Solutions
Genetic Analysis: An Integrated Approach (3rd Edition)
- You take DNA samples from a family with a history of the genetic disease spinal muscular atrophy, which results from many different mutations in the SMA gene. One mutation in the SMA gene is a 240-bp in-frame deletion mutation in the middle of an exon. Data from this family shows you that several individuals from the family have this mutation. What do you predict that you would find when comparing the mRNA and protein products of the mutated and unmutated SMA gene? Select all that apply. 1. The mRNA from the SMA is more stable than unmutated SMA mRNA. 2. The pre-mRNA from the SMA mutant is shorter than the unmutated SMA pre-mRNA. 3. The mature mRNA from the SMA mutant is longer than the unmutated SMA mRNA. 4. The protein from the mutated SMA is shorter than the unmutated SMA protein.arrow_forwardA glycine residue is in position 210 of the tryptophan synthetase enzyme of wild-type E. coli. If the codon specifying glycine is GGA, how many single-base substitutions will result in an amino acid substitution at position 210? What are they? How many will result if the wild-type codon is GGU?arrow_forwardConsider the following tRNAs, where the numbered forms represent the amino acids associated with them, answer briefly: PICTURE Question 1: The numbering indicates the order in which these tRNAs are recruited to the A site of the ribosome. Write the sequence of the mRNA being translated in the 5' - 3' direction Question 2: What is the amino acid sequence of the produced polypeptide? Question 3: Researchers discover that a mutation is in the anticodon of the gene encoding the proline tRNA of an individual. The anticodon sequence is normally 3' GGA 5', but in this individual the anticodon sequence is 3' GGG 5'. It appears that this individual suffers no adverse consequences. How can this be? (2 response items)arrow_forward
- Codons 24 to 66 represent an intron. At what point in the process of protein synthesis are introns removed? What is the name of the enzyme responsible for removing them?arrow_forwardIf the mRNA transcribed for this gene will be translated into a functional protein, how many amino acids will be used to build the polypeptide chain? what is the amino acid coded by the 25th codon? what is the amino acid coded by the last codon?arrow_forwarda. If a single transition occurs in a codon that specifies Phe, what amino acids can be specified by the mutated sequence? b. If a single transversion occurs in a codon that specifies Phe, what amino acids can be specified by the mutated sequence? c. If a single transition occurs in a codon that specifies Leu, what amino acids can be specified by the mutated sequence? d. If a single transversion occurs in a codon that specifies Leu, what amino acids can be specified by the mutated sequence?arrow_forward
- Several experiments were conducted to obtain information about how the eukaryotic ribosome recognizes the AUG start codon. In one experiment, the gene that encodes methionine initiator tRNA (tRNAiMet) was located and changed; specifically, the nucleotides that specify the anticodon on tRNAiMet were mutated so that the anticodon in the tRNA was 5′ –CCA–3′ instead of 5′ –CAU–3′. When this mutated gene was placed in a eukaryotic cell, protein synthesis took place, but the proteins produced were abnormal. Some of these proteins contained extra amino acids, and others contained fewer amino acids than normal. Q. What do these results indicate about how the ribosome recognizes the starting point for translation in eukaryotic cells? Explain your reasoning.arrow_forwardSeveral experiments were conducted to obtain information about how the eukaryotic ribosome recognizes the AUG start codon. In one experiment, the gene that encodes methionine initiator tRNA (tRNAiMet) was located and changed; specifically, the nucleotides that specify the anticodon on tRNAiMet were mutated so that the anticodon in the tRNA was 5′ –CCA–3′ instead of 5′ –CAU–3′. When this mutated gene was placed in a eukaryotic cell, protein synthesis took place, but the proteins produced were abnormal. Some of these proteins contained extra amino acids, and others contained fewer amino acids than normal. Q. If the same experiment had been conducted on bacterial cells, what results would you expect?arrow_forwardSeveral experiments were conducted to obtain information about how the eukaryotic ribosome recognizes the AUG start codon. In one experiment, the gene that encodes methionine initiator tRNA (tRNAiMet) was located and changed; specifically, the nucleotides that specify the anticodon on tRNAiMet were mutated so that the anticodon in the tRNA was 5′ –CCA–3′ instead of 5′ CAU–3′. When this mutated gene was placed in a eukaryotic cell, protein synthesis took place, but the proteins produced were abnormal. Some of these proteins contained extra aminoacids, and others contained fewer amino acids than normal. a. What do these results indicate about how the ribosome recognizes the starting point for translation in eukaryotic cells? Explain your reasoning. b. If the same experiment had been conducted on bacterial cells, what results would you expect? c. Explain why some of the proteins produced contained extra amino acids while others contained fewer amino acids than normal.arrow_forward
- The amino acid glycine is encoded by four codons: GGA, GGC, GGG, and GGU. Which of the following statements correctly explains this fact? The glycine anticodon contains the sequence CC, but the 5' base of the anticodon can pair nonspecifically with the 3' base of the codon. The glycine anticodon contains the sequence CC, but the 3' base of the anticodon can pair nonspecifically with the 5' base of the codon. Glycine tRNA has four anticodons, and the appropriate anticodon specifically pairs with the correct codon. There are four tRNAs for glycine, each of which has an anticodon that specifically pairs with the correct codon. all of the abovearrow_forwardSeveral experiments were conducted to obtain information about how the eukaryotic ribosome recognizes the AUG start codon. In one experiment, the gene that encodes methionine initiator tRNA (tRNAiMet) was located and changed; specifically, the nucleotides that specify the anticodon on tRNAi Met were mutated so that the anticodon in the tRNA was 5′ –CCA–3′ instead of 5′ –CAU–3′. When this mutated gene was placed in a eukaryotic cell, protein synthesis took place, but the proteins produced were abnormal. Some of these proteins contained extra amino acids, and others contained fewer amino acids than normal. a. What do these results indicate about how the ribosome recognizes the starting point for translation in eukaryotic cells? Explain your reasoning. b. If the same experiment had been conducted on bacterial cells, what results would you expect? c. Explain why some of the proteins produced contained extra amino acids while others contained fewer amino acids than normalarrow_forwardYou start by looking at the mutations that Yanofsky recovered in TrpA. One of these mutations affected amino acid number 177 and changed it from Leucine to Arginine – because Yanofsky recovered it in his screen, that means that having an Arginine in this position does not allow the TrpA gene to function properly. Assuming that this particular mutation induced by Yanofsky was a single nucleotide change, what are the possible codons of Leucine that could be found at this position in wild-type TrpA? What are the possible codons for Leucine that could be found in the mutant?. If you took this mutant E. Coli line (that has an Arginine at this location) and exposed it to a mutagen that could potentially change bases, what are the second mutations you would most likely discover that would restore the activity of the tryptophan synthetase gene and where would it be located?arrow_forward
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