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 6, Problem 17P
When Meselson and Stahl grew E. coli in 15N medium for many generations and then transferred the cells to 14N medium for one generation, they found that the bacterial DNA banded at a density intermediate between that of pure 15N DNA and pure 14N DNA following equilibrium density centrifugation. When they allowed the bacteria to replicate one additional time in 14N medium, they observed that half of the DNA remained at the intermediate density, while the other half banded at the density of pure 14N DNA. What would they have seen after an additional generation of growth in 14N medium? After two additional generations?
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When Meselson and Stahl grew E. coli in 15N mediumfor many generations and then transferred the cells to 14Nmedium for one generation, they found that the bacterial DNA banded at a density intermediate between that ofpure 15N DNA and pure 14N DNA following equilibrium density centrifugation. When they allowed thebacteria to replicate one additional time in 14N medium, they observed that half of the DNA remained atthe intermediate density, while the other half banded atthe density of pure 14N DNA. What would they haveseen after an additional generation of growth in 14Nmedium? After two additional generations?
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.
Suppose the experiment of Meselson and Stahl was performed on a sample of 8 cells, each containing one copy of its circular double-stranded DNA genome, and that had been growing on normal 14N medium. You then grew the cells for 3 generations in medium containing 15N. The outcome would be
A) 8 cells with single-stranded DNA molecules with 14N, and 24 cells with single-stranded DNA molecules with 15N. B) 16 cells with double-stranded DNA molecules with equal amounts of 14N and 15N, and 48 cells with double-stranded DNA molecules with 15N. C) 8 cells with double-stranded DNA molecules with equal amounts of 14N and 15N, and 24 cells with double-stranded DNA molecules with 15N. D) 8 cells with double-stranded DNA molecules with equal amounts of 14N and 15N, and 32 cells with double-stranded DNA molecules with 15N. E) 65 cells with single-stranded DNA molecules with 15N.
Chapter 6 Solutions
Genetics: From Genes to Genomes
Ch. 6 - Griffith, in his 1928 experiments, demonstrated...Ch. 6 - Griffith, in his 1928 experiments, demonstrated...Ch. 6 - During bacterial transformation, DNA that enters a...Ch. 6 - Nitrogen and carbon are more abundant in proteins...Ch. 6 - If 30 of the bases in human DNA are A, a what...Ch. 6 - Which of the following statements are true about...Ch. 6 - Imagine you have three test tubes containing...Ch. 6 - What information about the structure of DNA was...Ch. 6 - A portion of one DNA strand of the human gene...Ch. 6 - When a double-stranded DNA molecule is exposed to...
Ch. 6 - A particular virus with DNA as its genetic...Ch. 6 - The underlying structure of DNA is very simple,...Ch. 6 - Prob. 13PCh. 6 - Bacterial transformation and bacteriophage...Ch. 6 - The CAP protein is shown bound to DNA in Fig....Ch. 6 - In Meselson and Stahls density shift experiments...Ch. 6 - When Meselson and Stahl grew E. coli in 15N medium...Ch. 6 - If you expose human tissue culture cells for...Ch. 6 - Draw a replication bubble with both replication...Ch. 6 - a. Do any strands of nucleic acid exist in nature...Ch. 6 - As Fig. 6.21 shows, DNA polymerase cleaves the...Ch. 6 - The bases of one of the strands of DNA in a region...Ch. 6 - Replicating structures in DNA can be observed in...Ch. 6 - Indicate the role of each of the following in DNA...Ch. 6 - Draw a diagram of replication that is occurring at...Ch. 6 - Figure 6.18 depicts Watson and Cricks initial...Ch. 6 - Researchers have discovered that during...Ch. 6 - A DNA synthesizer is a machine that uses automated...Ch. 6 - Bacterial cells were coinfected with two types of...Ch. 6 - A yeast strain with a mutant spo11- allele has...Ch. 6 - Imagine that you have done a cross between two...Ch. 6 - The Neurospora octad shown came from a cross...Ch. 6 - From a cross between e f g and e f g strains of...Ch. 6 - In Step 6 of Fig. 6.27, the resolvase enzyme...Ch. 6 - Figure 6.31shows four potential outcomes of...Ch. 6 - Each of the substrates for site-specific...Ch. 6 - Prob. 37PCh. 6 - Suppose that you could inject a wild-type mouse...Ch. 6 - C31 is a type of bacteriophage that infects...Ch. 6 - Cre is a recombinase enzyme encoded by a gene in...Ch. 6 - Like Cre/loxP recombination, site-specific...
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