Genetics: Analysis and Principles
6th Edition
ISBN: 9781259616020
Author: Robert J. Brooker Professor Dr.
Publisher: McGraw-Hill Education
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Chapter 19, Problem 6CONQ
Summary Introduction
To review:
The terms that can be used to describe the second mutation in the lacY gene in the lac operonout of the following:
Reversion
Intragenic suppressor
Intergenic suppressor
Missense mutation
Introduction:
The lac operon found in bacterial species consists of three genes, namely, lacZ, lacY and lacA. LacZ codes for an enzyme known as β-galactosidase (cleaves lactose to form galactose and glucose), lacY codes for an enzyme known as lactose permease (allows entry of lactose inside the cell) and lacA codes for an enzyme known astransacetylase (adds chemical groups to other molecules).
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Lactose permease is encoded by the lacY gene of the lac operon.Suppose a mutation occurred at codon 64 that changed the normalglycine codon into a valine codon. The mutant lactose permease isunable to function. However, a second mutation, which changescodon 50 from an alanine codon to a threonine codon, is able torestore function. Is each of the following terms appropriate or inappropriate to describe this second mutation?A. ReversionB. Intragenic suppressorC. Intergenic suppressorD. Missense mutation
. Listed in parts a through g are some mutations that were found in the 5′ UTR of the trp operon of E. coli. What will the most likely effect of each of these mutations be on the transcription of the trp structural genes?
Q. A mutation that changes the Trp codons in region 1 of the mRNA 5′ UTR into codons for alanine
Listed in parts a through g are some mutations that were found in the 5′ UTR of the trp operon of E. coli. What will the most likely effect of each of these mutations be on the transcription of the trp structural genes? a. A mutation that prevents the binding of the ribosome to the 5′ end of the mRNA 5′ UTR b. A mutation that changes the Trp codons in region 1 of the mRNA 5′ UTR into codons for alanine c. A mutation that creates a stop codon early in region 1 of the mRNA 5′ UTR d. Deletions in region 2 of the mRNA 5′ UTR e. Deletions in region 3 of the mRNA 5′ UTR f. Deletions in region 4 of the mRNA 5′ UTR g. Deletion of the string of adenine nucleotides that follows region 4 in the 5′ UTR
Chapter 19 Solutions
Genetics: Analysis and Principles
Ch. 19.1 - 1. A mutation changes a codon that specifies...Ch. 19.1 - A down promoter mutation causes the promoter of a...Ch. 19.1 - 3. A mutation in one gene that reverses the...Ch. 19.1 - Which of the following is an example of a somatic...Ch. 19.2 - Prob. 1COMQCh. 19.3 - Which of the following is not an example of a...Ch. 19.3 - A point mutation could be caused by a....Ch. 19.3 - One way that TNRE may occur involves the formation...Ch. 19.4 - Nitrous acid replaces amino groups with keto...Ch. 19.4 - Prob. 2COMQ
Ch. 19.4 - Prob. 3COMQCh. 19.5 - The function of photolyase is to repair a....Ch. 19.5 - Which of the following DNA repair systems may...Ch. 19.5 - 3. In nucleotide excision repair in E. coli, the...Ch. 19.5 - Prob. 4COMQCh. 19.5 - An advantage of translesion-replicating...Ch. 19 - Is each of the following mutations a transition,...Ch. 19 - Prob. 2CONQCh. 19 - What does a suppressor mutation suppress? What is...Ch. 19 - Prob. 4CONQCh. 19 - X-rays strike a chromosome in a living cell and...Ch. 19 - Prob. 6CONQCh. 19 - Prob. 7CONQCh. 19 - 8. A point mutation occurs in the middle of the...Ch. 19 - Prob. 9CONQCh. 19 - Prob. 10CONQCh. 19 - 11. Is a random mutation more likely to be...Ch. 19 - 12. Which of the following mutations could be...Ch. 19 - Prob. 13CONQCh. 19 - Discuss the consequences of a germ-line versus a...Ch. 19 - Prob. 15CONQCh. 19 - Explain how a mutagen can interfere with DNA...Ch. 19 - What type of mutation (transition, transversion,...Ch. 19 - Explain what happens to the sequence of DNA during...Ch. 19 - Distinguish between spontaneous and induced...Ch. 19 - Prob. 20CONQCh. 19 - Prob. 21CONQCh. 19 - Prob. 22CONQCh. 19 - Trinucleotide repeat expansions (TNREs) are...Ch. 19 - 24. With regard to TNRE, what is meant by the term...Ch. 19 - 25. What is the difference between the mutation...Ch. 19 - Achondroplasia is a rare form of dwarfism. It is...Ch. 19 - Prob. 27CONQCh. 19 - In the treatment of cancer, the basis for many...Ch. 19 - Prob. 29CONQCh. 19 - 30. Which of the following examples is likely to...Ch. 19 - Prob. 31CONQCh. 19 - Prob. 32CONQCh. 19 - Prob. 33CONQCh. 19 - With regard to the repair of double-strand breaks,...Ch. 19 - Prob. 35CONQCh. 19 - Prob. 36CONQCh. 19 - 37. Three common ways to repair changes in DNA...Ch. 19 - Prob. 38CONQCh. 19 - Prob. 39CONQCh. 19 - Explain how the technique of replica plating...Ch. 19 - 2. Outline how you would use the technique of...Ch. 19 - 3. From an experimental point of view, is it...Ch. 19 - Prob. 4EQCh. 19 - Prob. 5EQCh. 19 - 6. Richard Boyce and Paul Howard-Flanders...Ch. 19 - In E. coli, a variety of mutator strains have been...Ch. 19 - 2. Discuss the times in a person’s life when it is...Ch. 19 - A large amount of research is aimed at studying...
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- In addition to observing similarities to the lac operon, you also notice that this gene is regulated via attenuation, similar to the trp operon. Based on this similarity to this model operon, you could state that ___________. Group of answer choices If a terminator loop forms in the DNA, the expression of the structural genes is halted. The formation of the terminator hairpin followed by a series of Uracil (UUUUUUU) functions similar to Rho-Independent termination to result in the stopping of transcription. The transcription of a leader sequence affects the translation of the structural genes. Never mind – all of these statements are true! Attenuation will be the primary means of transcriptional regulation, with a repressor used as a back up option.arrow_forwardImagine that a new strain of E. coli is discovered, and it contains the following novel genetic region including the lacI gene and the lac operon: *see image* Upstream of the promoter associated with the lac operon, there is a new operator element "Oν" (O-"nu"). This new operator has high sequence homology to O1, the DNA element that is bound with the highest affinity by the lac repressor. What would be the impact of this new genetic element regarding behavior of the operonin the absence (vs. the presence) of lactose and allolactose? Answer in terms of the protein levels of the lac repressor, as well as the proteins encoded by the genes lacZ/Y/A in the downstream region of the operon. Remember that proteins, once expressed/generated, will not persist forever, and that they have a natural lifetime (ending when they are degraded by the cell).arrow_forwardIf the above gene is one of the three structural genes of the lac operon that codes for the protein/ enzyme responsible for breaking lactose into two molecules of simple sugars, what triggers the activation of this gene? a. Absence of Inhibitory protein b. Presence of lactose c. Absence of lactose d. Presence of Inhibitory protein e. Absence of Regulatory proteinarrow_forward
- If the two trp codons in the leader sequence were mutated to stop codons, what effect would it have on gene expression of that operon.arrow_forwardWhat would happen if the operator sequence of the lac operon contained a mutation that prevented the repressor protein from binding the operator? (Explain what would happen both in the presence and absence of lactose)arrow_forward. Listed in parts a through g are some mutations that were found in the 5′ UTR of the trp operon of E. coli. What will the most likely effect of each of these mutations be on the transcription of the trp structural genes? Q. Deletions in region 3 of the mRNA 5′ UTRarrow_forward
- . Listed in parts a through g are some mutations that were found in the 5′ UTR of the trp operon of E. coli. What will the most likely effect of each of these mutations be on the transcription of the trp structural genes? Q. A mutation that prevents the binding of the ribosome to the 5′ end of the mRNA 5′ UTRarrow_forwardIn the lac operon (below), how will expression of the genes lacZ and lacy be effect by a mutation in the repressor protein (encoded by lach) that prevents it from binding the operator sequence (lacO) in the absence of lactose? Explain the answerarrow_forwardWhat experimental results would indicate that the mutation lacISlacIS is dominant to lacI+lacI+? In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a repressed state in the absence of lactose. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a constitutive state in the absence of the repressor. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in an activated state in the presence of lactose. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a repressed state in the absence of the repressor. In lacISlacIS/lacI+lacI+ partial diploids, the lac operon is in a repressed state in the presence of lactose.arrow_forward
- In the lac operon system, do the inducers act at the transcription or translation level? Explain why it acts in that level in a short but concise way.arrow_forwardLet’s suppose you have isolated a mutant strain of E. coli in which the lac operon is constitutively expressed. In other words, the operon is turned on in the presence or absence of lactose. One possibility is that the mutation may block the transcription of the lacI gene, thereby preventing the synthesis of lac repressor. A second possibility is that the mutation could alter the sequence of the lac operon in a way that prevents the repressor protein from binding to the operator. How would you distinguish between these two possibilities?arrow_forwardExplain why inactivation of the O1 sequence of the lac operator almost completely abolishes repression of the lac operon.arrow_forward
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