Concepts of Genetics (12th Edition)
12th Edition
ISBN: 9780134604718
Author: William S. Klug, Michael R. Cummings, Charlotte A. Spencer, Michael A. Palladino, Darrell Killian
Publisher: PEARSON
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Chapter 11, Problem 1PDQ
HOW DOWE KNOW?
In this chapter, we focused on how DNA is replicated and synthesized. We also discussed recombination at the DNA level. Along the way, we encountered many opportunities to consider how this information was acquired. On the basis of these discussions, what answers would you propose to the following fundamental questions?
- (a) What is the experimental basis for concluding that DNA replicates semiconservatively in both bacteria and eukaryotes?
- (b) How was it demonstrated that DNA synthesis occurs under the direction of DNA polymerase III and not polymerase I?
- (c) How do we know that in vivo DNA synthesis occurs in the 5′ to 3′ direction?
- (d) How do we know that DNA synthesis is discontinuous on one of the two template strands?
- (e) What observations reveal that a “telomere problem” exists during eukaryotic
DNA replication , and how did we learn of the solution to this problem?
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Suppose that E. coli synthesizes DNA at a rate of 100,000 nucleotides per minute and takes 40 minutes to replicate its chromosome. (a) How many base pairs are present in the entire E. coli chromosome? (b) What is the physical length of the chromosome in its helical configuration—that is, what is the circumference of the chromosome if it were opened into a circle?
During high stress environments, it has been found that some bacteria activate a genetic mechanism that allows them to incorporate more mutations into the DNA during replication. Would the following two enzymes be impacted by such a mechanism? In each case, provide a reason for your answer. i) DNA polymerase IIIii) Helicase
This is a three part question:
Figure B in Box 4.1 illustrates the results of the Meselson-Stahl experiment after a single cycle of replication in 14N.
(a) Explain the results they observed after two rounds of replication in 14N medium.
(b) Draw out the expected results if a third round of replication were allowed in 14N medium.
(c) Two other models for template-directed replication were considered as alternatives to semi-conservative replication. One of these was conservative replication, in which the parental strands were unpaired, replicated, then reannealed such that the parental strands stayed together and the newly synthesized strands were together. The second model was dispersive replication, in which one strand was used as the template for polymerization, then the polymerase switched to using the other strand as the template, and subsequently switched back and forth between the two strands until bother were fully replicated. Each of these models is ruled out by one of your…
Chapter 11 Solutions
Concepts of Genetics (12th Edition)
Ch. 11 - In the Meselson-Stahl experiment, which of the...Ch. 11 - An alien organism was investigated. When DNA...Ch. 11 - Why might mutations in genes encoding telomerase...Ch. 11 - Although the brother is an immunologically matched...Ch. 11 - Prob. 3CSCh. 11 - HOW DOWE KNOW? In this chapter, we focused on how...Ch. 11 - CONCEPT QUESTION Review the Chapter Concepts list...Ch. 11 - Compare conservative, semiconservative, and...Ch. 11 - Describe the role of 15N in the MeselsonStahl...Ch. 11 - Predict the results of the experiment by Taylor,...
Ch. 11 - What are the requirements for in vitro synthesis...Ch. 11 - In Kornbergs initial experiments, it was rumored...Ch. 11 - How did Kornberg assess the fidelity of DNA...Ch. 11 - Which characteristics of DNA polymerase I raised...Ch. 11 - Kornberg showed that nucleotides are added to the...Ch. 11 - What was the significance of the polA1 mutation?Ch. 11 - Summarize and compare the properties of DNA...Ch. 11 - List and describe the function of the ten subunits...Ch. 11 - Distinguish between (a) unidirectional and...Ch. 11 - List the proteins that unwind DNA during in vivo...Ch. 11 - Define and indicate the significance of (a)...Ch. 11 - Outline the current model for DNA synthesis.Ch. 11 - Why is DNA synthesis expected to be more complex...Ch. 11 - Suppose that E. coli synthesizes DNA at a rate of...Ch. 11 - Several temperature-sensitive mutant strains of E....Ch. 11 - While many commonly used antibiotics interfere...Ch. 11 - Describe the end-replication problem in...Ch. 11 - Many of the gene products involved in DNA...Ch. 11 - In 1994, telomerase activity was discovered in...Ch. 11 - The genome of D. melanogaster consists of...Ch. 11 - Prob. 26ESPCh. 11 - DNA polymerases in all organisms add only 5...Ch. 11 - Assume that the sequence of bases shown below is...Ch. 11 - Reiji and Tuneko Okazaki conducted a now classic...Ch. 11 - Consider the drawing of a dinucleotide below. (a)...Ch. 11 - To gauge the fidelity of DNA synthesis, Arthur...
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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
- A temperature-sensitive mutation is one in which the defect is not presented functionally until the temperature is raised. In the case described below, the enzymes function normally in bacteria at 37 °C, but are non-functional at 40 °C. Predict the detailed molecular consequences of a loss of function in a temperature-sensitive mutant for each of the following enzymes: a) DNA gyrase, b) DNA polymerase III, c) DNA ligase, d) DNA polymerase I.arrow_forwardThe E. coli chromosome is 1.28 mm long. Under optimal conditions, thechromosome is replicated in 40 minutes.(a) What is the distance traversed by one replication fork in 1 minute?(b) If replicating DNA is in the B form (10.4 base pairs per turn), how manynucleotides are incorporated in 1 minute in one replication fork?(c) If cultured human cells (such as HeLa cells) replicate 1.2 m of DNAduring a five-hour S phase and at a rate of fork movement one-tenthof that seen in E. coli, how many origins of replication must the cellscontain?(d) What is the average distance, in kilobase pairs, between these origins?arrow_forward(a) How fast does template DNA spin (expressed in revolutions per second) at an E. coli replication fork? (b) What is the velocity of movement (in micrometers per second) of DNA polymerase III holoenzyme relative tothe template?arrow_forward
- The E. coli chromosome is 1.28 mm long. Under optimal conditions the chromosome is replicated in 40 minutes. (a) What is the distance traversed by one replication fork in 1 minute? (b) If replicating DNA is in the B form (10.4 base pairs per turn), how many nucleotides are incorporated in 1 minute in one replica- tion fork? (c) If cultured human cells (such as Hela cells) replicate 1.2 m of DNA during a 5-hour S phase and at a rate of fork movement one- tenth of that seen in E. coli, how many origins of replication must the cells contain? (d) What is the average distance, in kilobase pairs, between these origins?arrow_forwardMany of the gene products involved in DNA synthesis were initially defined by studying mutant E. coli strains that could not synthesize DNA. (a) The dnaE gene encodes the a subunit of DNA polymerase III. What effect is expected from a mutation in this gene? How could the mutant strain be maintained? (b) The dnaQ gene encodes the e subunit of DNA polymerase. What effect is expected from a mutation in this gene?arrow_forwardYou conducted an experiment to determine the mechanism of DNA replication in the hypothetical organism Fungus mungus. Your data shows that synthesis of newly replicated DNA from F. mungus is discontinuous on both strands of the replication fork. Does this result support or not support the hypothesis that F. mungus replicates its DNA by the same mechanism as yeast? Briefly explain your answer.arrow_forward
- During high stress environments, it has been found that some bacteria activate a genetic mechanism that allows them to incorporate more mutations into the DNA during replication. Would the following two enzymes be impacted by such a mechanism? (i)DNA polymerase IIIii) Helicasearrow_forwardOn further analysis of the DNA described in conceptual questionC21, you discover that the triplex DNA in this alien organism iscomposed of a double helix with a third strand wound within themajor groove (just like the DNA in Figure shown). How would youpropose that this DNA is able to replicate itself? In your answer,be specific about the base-pairing rules within the double helixand which part of the triplex DNA would be replicated first.arrow_forwardWhat are the three models of DNA replication? With the aid of illustrations, show how the Meselson Stahl experiment come to the conclusion of one model of DNA replication. Is DNA replication bidirectional? How did you arrive at this conclusion? Explain the bacterial replication model that supports this conclusion.arrow_forward
- Consider the experiment conducted by Meselson and Stahl in which they used 14N and 15N in cultures of E. coli and equilibrium density gradient centrifugation. Draw pictures to represent the bands produced by bacterial DNA in the centrifuge tube before the switch to medium containing 14N and after one, two, and three rounds of replication in that medium. Use separate sets of drawings to show the bands that would appear if replication were (a) semiconservative; (b) conservative; (c) dispersive.arrow_forwardYou are studying a colony of cells and determine that some of these cells have a mutated DNA polymerase I that results in loss of function of this enzyme. A) What will the effect of the mutation in DNA polymerase I be on DNA replication? In your answer make sure to describe what would be observed in the leading and lagging strand and explain your reasoning. B) Will this mutation in DNA polymerase I have an impact on another step in DNA replication? In your answer make sure to indicate whether DNA replication will be impacted or not. If it is not, explain why. If it is impacted, then describe the step that is impacted and name the molecule or enzyme involved.arrow_forwardDNA ligase has the ability to relax supercoiled circular DNA in the presence of AMP but not in its absence. (a) What is the mechanism of this reaction, and why does it depend on AMP? (b) How could you determine that supercoiled DNA had in fact been relaxed?arrow_forward
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