ESSENTIALS OF GENETICS CHAPTER 10
QUESTIONS AND ANSWERS
1. Semiconservative replication: Each replicated DNA molecule would consist of one "old"
and one "new" strand
2. Conservative replication: the parental strands are dispersed into two new double helices
following replication. Hence, each strand consists of both old and new DNA
-would involve cleavage of the parental strands during replication
3. Meselson-Stahl experiment: grew E. coli cells for many generations in a medium that had
15N as the only nitrogen source and after many generations, almost all nitrogen containing e. coli
cells, including the nitrogenous bases of DNA, contained this heavier isotope
-semiconservative
4. Sedimentation equilibrium centrifugation: samples are forced by centrifugation
through a density gradient of a heavy metal salt. Molecules of DNA will reach equilibrium when their
density equals the density of the gradient medium
5. Autoradiography: when applied cytologically, pinpoints the location of a radioisotope in a
cell
6. Taylor, Woods, and Hughes: demonstrated semiconservative replication in eukaryotes
using the root
tips of the board bean as the source of dividing cells
7. Origin of replication: where along the chromosome DNA replication is initiated
8. Replication fork: each point along the chromosome where replication is occurring, the strands
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, ESSENTIALS OF GENETICS CHAPTER 10
QUESTIONS AND ANSWERS
of the helix
are unwound
-will initially appear at the point of origin of synthesis and then move along the DNA duplex as
replication proceeds
9. Replicon: The length of DNA that is replicated following one initiation even at a single origin
10. the presence of a single origin is characteristic of: bacteria, because they
only have one
circular chromosome
11. Since DNA synthesis in bacteriophages and bacteria originates
at a single point, the entire chromosome constitutes as: one replicon
12. DNA polymerase I: was able to direct DNA synthesis in a cell-free (in vitro) system
-isolated from E. Coli by Kornberg
-The way in which each nucleotide is added to the growing chain is a function of the specificity of DNA
polymerase I
-believed to be responsible for removing the primer, as well as for the synthesis that fills gaps produced
after this removal
13. Chain elongation: occurs in the 5' to 3' direction by the addition of one nucleotide at a
time to the growing
3' end
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9
QUESTIONS AND ANSWERS
1. Semiconservative replication: Each replicated DNA molecule would consist of one "old"
and one "new" strand
2. Conservative replication: the parental strands are dispersed into two new double helices
following replication. Hence, each strand consists of both old and new DNA
-would involve cleavage of the parental strands during replication
3. Meselson-Stahl experiment: grew E. coli cells for many generations in a medium that had
15N as the only nitrogen source and after many generations, almost all nitrogen containing e. coli
cells, including the nitrogenous bases of DNA, contained this heavier isotope
-semiconservative
4. Sedimentation equilibrium centrifugation: samples are forced by centrifugation
through a density gradient of a heavy metal salt. Molecules of DNA will reach equilibrium when their
density equals the density of the gradient medium
5. Autoradiography: when applied cytologically, pinpoints the location of a radioisotope in a
cell
6. Taylor, Woods, and Hughes: demonstrated semiconservative replication in eukaryotes
using the root
tips of the board bean as the source of dividing cells
7. Origin of replication: where along the chromosome DNA replication is initiated
8. Replication fork: each point along the chromosome where replication is occurring, the strands
1/
9
, ESSENTIALS OF GENETICS CHAPTER 10
QUESTIONS AND ANSWERS
of the helix
are unwound
-will initially appear at the point of origin of synthesis and then move along the DNA duplex as
replication proceeds
9. Replicon: The length of DNA that is replicated following one initiation even at a single origin
10. the presence of a single origin is characteristic of: bacteria, because they
only have one
circular chromosome
11. Since DNA synthesis in bacteriophages and bacteria originates
at a single point, the entire chromosome constitutes as: one replicon
12. DNA polymerase I: was able to direct DNA synthesis in a cell-free (in vitro) system
-isolated from E. Coli by Kornberg
-The way in which each nucleotide is added to the growing chain is a function of the specificity of DNA
polymerase I
-believed to be responsible for removing the primer, as well as for the synthesis that fills gaps produced
after this removal
13. Chain elongation: occurs in the 5' to 3' direction by the addition of one nucleotide at a
time to the growing
3' end
2/
9
