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 8, Problem 9P
The results shown in Fig. 8.5 may have struck you as incongruous because many synthetic RNAs that lacked AUG start codons (such as poly-U) were nonetheless translated into polypeptides in vitro. The reason this experiment was possible is that Marshall Nierenberg found that a high concentration of Mg2+ ions in the test tube, much higher than that found in cells, allows ribosomes to initiate translation at any position on an RNA molecule. Predict the outcomes of in vitro translation with each of the following synthetic mRNAs at both high and low Mg2+ concentrations:
| a. | poly-UG (UGUGUG...) |
| b. | poly-CAUG (CAUGCAUGCAUG...) |
| c. | poly-GUAU (GUAUGUAUGUAU...) |
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Students have asked these similar questions
Phenylalanine (Phe) is encoded by either UUU or UUC, while Tyrosine (Tyr) is encoded only by UAC and UAU. Given this, and given what you know about tRNA selection, will Phenylalanine be found in the resulting polypeptides? (Assume translation will happen even without a start codon; Also this is a bit tricky, so review the contents of the assay before answering.)
Yes, in part because phenylalanine is also coded for by UUU
Yes, because ribosomes select the amino acid regardless of the anticodon sequence
Yes, for both of the reasons listed above.
No, because it is no longer attached to the tRNA with the GAA anticodon
Suppose RNA is synthesized in vitro using the polynucleotide phosphorylase enzyme with a 3:1 ratio of C and G nucleotides (3C:1G ratio). If you were to use the resulting RNA to synthesize protein in an in vitro translation system, what percentage of the total amino acids in the protein would be made up of alanine (Ala)?
56.25%
6.25%
18.75%
0%
14%
Shown here is a theoretical viral mRNA sequence 5′-AUGCAUACCUAUGAGACCCUUGGA-3′ (a) Assuming that it could arise from overlapping genes, how many different polypeptide sequences can be produced? Using the chart in Figure 12–7, what are the sequences? (b) A base-substitution mutation that altered the sequence in part (a) eliminated the synthesis of all but one polypeptide. The altered sequence is shown below. Use Figure 12–7 to determine why it was altered. 5′-AUGCAUACCUAUGUGACCCUUGGA-3′
Chapter 8 Solutions
Genetics: From Genes to Genomes
Ch. 8 - For each of the terms in the left column, choose...Ch. 8 - Match the hypothesis from the left column to the...Ch. 8 - How would the artificial mRNA 5GUGUGUGU . . . 3 be...Ch. 8 - An example of a portion of the T4 rIIB gene in...Ch. 8 - Consider Crick and Brenners experiments in Fig....Ch. 8 - The HbSsickle-cell allele of the human -globin...Ch. 8 - The following diagram describes the mRNA sequence...Ch. 8 - The amino acid sequence of part of a protein has...Ch. 8 - The results shown in Fig. 8.5 may have struck you...Ch. 8 - Identify all the amino acid-specifying codons in...
Ch. 8 - Before the technology existed to synthesize RNA...Ch. 8 - A particular protein has the amino acid sequence...Ch. 8 - How many possible open reading frames frames...Ch. 8 - Prob. 14PCh. 8 - Charles Yanofsky isolated many different trpA-...Ch. 8 - The sequence of a segment of mRNA, beginning with...Ch. 8 - You identify a proflavin-generated allele of a...Ch. 8 - Using recombinant DNA techniques which will be...Ch. 8 - Describe the steps in transcription that require...Ch. 8 - Chapters 6 and 7 explained that mistakes made by...Ch. 8 - The coding sequence for gene F is read from left...Ch. 8 - If you mixed the mRNA of a human gene with the...Ch. 8 - Prob. 23PCh. 8 - The Drosophila gene Dscam1 encodes proteins on the...Ch. 8 - Describe the steps in translation that require...Ch. 8 - Locate as accurately as possible the listed items...Ch. 8 - Concerning the figure for Problem 26: a. Which...Ch. 8 - a. Can a tRNA exist that has the anticodon...Ch. 8 - For parts a and b of Problem 28, consider the DNA...Ch. 8 - Remembering that the wobble base of the tRNA is...Ch. 8 - Prob. 31PCh. 8 - The yeast gene encoding a protein found in the...Ch. 8 - The sequence of a complete eukaryotic gene...Ch. 8 - Arrange the following list of eukaryotic gene...Ch. 8 - Prob. 35PCh. 8 - The human gene for 2 lens crystallin has the...Ch. 8 - In prokaryotes, a search for genes in a DNA...Ch. 8 - a. The genetic code table shown in Fig. 8.2...Ch. 8 - a. Very few if any eukaryotic genes contain tracts...Ch. 8 - Explain how differences in the initiation of...Ch. 8 - Do you think each of the following types of...Ch. 8 - Null mutations are valuable genetic resources...Ch. 8 - The following is a list of mutations that have...Ch. 8 - Considering further the mutations described in...Ch. 8 - Adermatoglyphia described previously in Problem 18...Ch. 8 - Prob. 46PCh. 8 - You learned in Problem 21 in Chapter 7 that the...Ch. 8 - When 1 million cells of a culture of haploid yeast...Ch. 8 - Why is a nonsense suppressor tRNATyr, even though...Ch. 8 - A mutant B. adonis bacterium has a nonsense...Ch. 8 - You are studying mutations in a bacterial gene...Ch. 8 - Another class of suppressor mutations, not...Ch. 8 - Yet another class of suppressor mutations not...Ch. 8 - At least one nonsense suppressing tRNA is known...Ch. 8 - An investigator was interested in studying UAG...Ch. 8 - Prob. 56PCh. 8 - In certain bacterial species, pyrrolysine Pyl,...Ch. 8 - Canavanine is an amino acid similar to arginine...
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Need a deep-dive on the concept behind this application? Look no further. Learn more about this topic, biology and related others by exploring similar questions and additional content below.Similar questions
- The E. coli genome contains approximately 4639 kb. (a) How many copies of the 6-bp recognition sequence for the trp repressor would be expected to occur in the E. coli chromosome? (b) Explain why it is advantageous for the trp repressor to be a dimer that recognizes two adjacent 6-bp sequences.arrow_forwardRefer to the DNA sequence provided: 3’ -TACTGAAGCGGCAGCCCCGCATGAGTAGACCTTACT-5’ a. What is the mRNA transcript of the anticoding strand of the DNA model? b. What is the amino acid sequence of the polypeptide chain that will be translated from the mRNA in (a)?arrow_forwardSuppose RNA is synthesized in vitro using the polynucleotide phosphorylase enzyme with a 3:1 ratio of C and G nucleotides (3C:1G ratio). If you were to use the resulting RNA to synthesize protein in an in vitro translation system, what percentage of the total amino acids in the protein would be made up of proline (Pro)? 56.25% 6.25% 42.19% 18.75% 0%arrow_forward
- (c) By binding one L-tryptophan molecule/monomer, the trp repressor binds to DNA to suppress syn- thesis of L-tryptophan in E. coli. Below is the amino acid sequence of the helix – (reverse) turn – helix region of the trp repressor that binds to DNA compared to the sequence of the corresponding DNA binding motif of the Prl protein, a different type of repressor protein. A diagram of the trp repressor dimer is also shown. reverse turn trp helix 4 70 Trp -Gly-Glu-Met-Ser-Gln-Arg-Glu-Leu-Lys-Asn-Glu-Leu-Gly-Ala-Gly- Ile- Prl -Ser-Glu-Glu-Ala-Lys-Glu-Glu-Leu-Ala-Lys-Lys-Cys-Gly-Ile-Thr- Val- Pri heilix trp helix 5 80 90 Trp Ala-Thr-Ile-Thr-Arg-Gly-Ser sgn-Ser-Leu-Lys-Ala-Ala- Prl Ser-Gln-Val-Ser-Asn-Trp-Phe-Gly-Asn-Lys-Arg-Ile-Arg- Prl helixarrow_forwardEven though the lac Z, Y, and A structural genes are transcribed as a single polycistronic mRNA, each gene contains the initiation and termination signals essential for translation. Predict what will happen when a cell growing in the presence of lactose contains a deletion of one nucleotide (a) early in the Z gene and (b) early in the A gene.arrow_forwardYou can successfully synthesize ovalbumin protein (eukaryotic) in the laboratory, with all the necessary components for translation in vitro. To further study translation, you vary some of the conditions and observe significantly lower level of ovalbumin protein production. Which of the following options could be a reason for this observation? Select all that apply. Ovalbumin mRNA is missing the 5'-cap A chemically. modified GTP that cannot be hydrolyzed is added Ovalbumin mRNA has a mutated Shine-Dalgarno sequence Methionine charged tRNA has not been addedarrow_forward
- in a clever experiment performed in 1962, a cysteine already attached to its tRNA was chemically converted to an alanine. these “hybrid” tRNA molecules were then added to a cell- free translation system from which the normal cysteine-tRNAs had been removed. When the resulting protein was analyzed, it was found that alanine had been inserted at every point in the polypeptide chain where cysteine was supposed to be. Discuss what this experiment tells you about the role of aminoacyl- tRNA synthetases during the normal translation of the genetic code.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 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_forwardThe sequence of the sense strand of a mammalian gene is (shown). Determine the sequences of the mature RNA and the encoded protein. Assume that transcription initiates at a G approximately 25 bp downstream of the TATAATA sequence, that each 5′ splice site has the sequence AG/GUAAGU, and that each 3′ splice site has the sequence CAG/G (where / marks the location of the splice).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_forwardThis is the sense strand of a mammalian gene. Determine the sequence of the mature mRNA. Assume transcription starts approxiamtely 25 bp downstreams from the TATAAT box, that the 5' splice site is AG/GUAAGU and that the 3' splice site is AG\GN. / marks the 5' splice site and \ marks the 3' splice site. N means any nucleotide. (In this problem, there are no branch point A's or polyY tracts. Please mark the splice sites as defined above. (5'=/ and 3'=\) and underline the mature mRNA. Do not use alternate splicing. TATAATACGCGCAATACAATCTACAGCTTCGCGTAAATCGTAGGTAAGTTGTAATAAATATAAGTGAGT ATGATAGGGCTTTGGACCGATAGATGCGACCCTGGAGGTAAGTATAGATAATTAAGCACAGGCATGCA GGGATATCCTCCAAATAGGTAAGTAACCTTACGGTCAATTAATTAGGCAGTAGATGAATAAACGATAT CGATCGGTTAGGTAAGTCTGATarrow_forward
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