In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated?
(a) at the transition between G1 and S
(b) when cells enter G0
(c) during M
(d) at the end of G2
Choice (d) is correct. It does not make sense to monitor DNA replication before S phase because DNA replication has not yet occurred [choice (a)]. When cells enter G0, they do not replicate their DNA [choice (b)]. During M phase, chromosomes are condensed for chromosome segregation, so it would be difficult for the cell to examine the replicated DNA for errors at that point[choice (c)].
You might also like to view...
For the following pedigree, what does the green circle in the fourth generation represent?
A. male without the disease B. female with the disease C. male with the disease D. female without the disease
In the United States, the largest group of endangered species is:
a. mammals. b. flowering plants. c. insects. d. birds. e. amphibians
A population of lizards lives in a rocky area next to a desert. Some lizards are light colored and blend into the sand. Others are dark and blend into the rocks. What may happen to this population of lizards over time?
A. They may evolve into two separate species as a result of disruptive selection. B. They may remain one species as a result of stabilizing selection. C. They may remain one species as a result of directional selection. D. They may evolve into two separate species as a result of directional selection. E. They may remain one species as a result of disruptive selection.
An episome is
A. a plasmid that gives bacteria the ability to exchange DNA with another bacterial cell. B. a plasmid that can turn a bacteria that is harmless into a strain that can cause disease. C. a plasmid that can make bacterial cells resistant to antibiotics. D. a plasmid that gives bacteria the ability to degrade toluene. E. a plasmid that can exist either autonomously in the cytoplasm or as part of a chromosome.