Exceptions to the universality of the genetic code were once thought to be rare, but more and more exceptions are being found. As mentioned in the text, one study found that a significant proportion of bacteria in the environment use nonuniversal codons. Can you think of any advantages for an organism using nonuniversal codons?

Exceptions to the universality of the genetic code were once thought to be rare, but more and more exceptions are being found. As mentioned in the text, one study found that a significant proportion of bacteria in the environment use nonuniversal codons. Can you think of any advantages for an organism using nonuniversal codons?

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter11: Genome Alterations: Mutation And Epigenetics

Section: Chapter Questions

Problem 14QP: In the gene-coding sequence shown here, which of the following events will produce a frameshift...

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Geneticists have found that when they cut out a eukaryotic gene from genomic DNA that they can hybridize one of the strands of that gene to the mRNA for that gene by allowing the strands to hydrogen bond. Why is it sometimes claimed that alternative splicing of exons from a single gene results in a set of proteins of related function?
Yeast have 8 similar tRNA genes with the anticodon 5’-GUA. A researcher mutates one of these genes to change its anticodon to 5’-GUU. a) What codon did the tRNA originally decode? b) What codon does the mutated tRNA decode?
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The genetic code is thought to have evolved to maximize genetic stability by minimizing the effect on protein function of most substitution mutations (single-base changes). We will use the six arginine codons to test this idea. Consider all of the substitutions that could affect all of the six arginine codons.(a) How many total mutations are possible?(b) How many of these mutations are “silent,” in the sense that the mutantcodon is changed to another Arg codon?(c) How many of these mutations are conservative, in the sense that an Argcodon is changed to a functionally similar Lys codon?
Consider the following original coding sequence of a gene that codes for a short 5- amino acid polypeptide: 5'-ATGGGCTCGAACTCATAA-3' Using the genetic code and the amino acid table below, which of the following sequences arises from a non-conservative missense mutation in the original sequence shown above? First base in codon U U A UUU UUC- UUA UUG- CUU CUC CUA CUG- U Phe (F) Leu (L) Leu (L) Second base in codon Val (V) UCU - UCC UCA UCG CCU CCC CCA CCG AUU ACU- AUC Ile (1) ACC AUA- ACA AUG Met (M) start ACG GUU GCU- GUC GCC GUA GCA GUG GCG- C Ser (S) Pro (P) Thr (T) Ala (A) UAU UAC UAAT UAG CAU CAC CAA CAG AAU AAC AAA AAG GAU GAC GAA GAG A Tyr (Y) STOP His (H) Gln (Q) Asn (N) Lys (K) Asp (D) Glu (E) G UGU UGC UGA STOP UGG Trp (W) Cys (C) CGU CGC CGA CGG AGU AGC AGA 1 AGG GGU- GGC GGA GGG Arg (R) Ser (S) Arg (R) Gly (G) U C A G U C A G U C A G U C A G Last base in codon
Yeast have 8 similar tRNA genes with the anticodon 5'-GUA. A researcher mutates one of these genes to change its anticodon to 5'-GUU. a) What codon did the tRNA originally decode? Name the amino acid. b) What codon does the mutated tRNA decode? Name the amino acid.
Knowing that the genetic code is almost universal, a scientist uses molecular biological methods to insert the human β-globin gene (Shown in Figure 17.11) into bacterial cells, hoping the cells will express it and synthesize functional β-globin protein. Instead, the protein produced is nonfunctional and is found to contain many fewer amino acids than does β-globin made by a eukaryotic cell. Explain why.
In studying the mechanism of a particular enzyme, for which the cloned gene is available, you wish to change a putative active site histidine residue to a proline by site-directed mutagenesis. The His codon to be changed is 5′-CAC. You wish to change it to 5′-CCC, one of four Pro codons. The nucleotide sequence surrounding the His codon is 5′-CTGGAATCTCACTTTATCTGG-3′. Write the nucleotide sequence of an oligonucleotide (a 21-mer) that could force the conversion of the CAC codon to CCC in a site-directed mutagenesis operation
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Consider the following wild-type and mutant sequences:Wild-type ....CTTGCAAGCGAATC....Mutant ....CTTGCTAGCGAATC....The substitution shown seems to have created a stop codon. What further information do you need to be confident that it has done so?
In the gene-coding sequence shown here, which of the following events will produce a frameshift after the last mutational site? a. insertion of an A after the first codon b. deletion of the second codon (AAA) c. insertion of TA after the second codon and deletion of CG in the fourth codon d. deletion of AC in the third codon
Geneticists have found that when they cut out a eukaryotic gene from genomic DNA that they can hybridize one of the strands of that gene to the mRNA for that gene by allowing the strands to hydrogen bond. Why did the appearance of these hybridized strands provide evidence of the existence of introns in eukaryotic genes?