Genetic Analysis 2nd Edition By Sanders – Test Bank
Chapter 11 Chromosome Structure
11.1 Multiple-Choice Questions
1) A virus is a noncellular infectious particle containing nucleic acid. Which type of nucleic acid listed below can be found within viruses?
E) all of the above
2) Viruses are not cellular; they lack most of the features belonging to a cell. They are particles consisting of __________.
A) a protein structure with genetic material contained inside
B) naked genetic material
C) genetic material surrounded by a protective carbohydrate shell
D) genetic material associated with additional proteins for viral replication
E) both A and D
3) Where are bacterial chromosomes located within the cell?
5) You have isolated DNA for PCR and accidentally added topoisomerase instead of polymerase to your sample. What would you expect if you ran this DNA sample on a gel?
A) The DNA would show increased supercoiling and have a lower electrophoretic mobility.
B) The DNA would show decreased supercoiling and have a higher electrophoretic mobility.
C) The DNA would show increased supercoiling and have a higher electrophoretic mobility.
D) The DNA would show decreased supercoiling and have a lower electrophoretic mobility.
E) The DNA would show decreased supercoiling, but electrophoretic mobility will be unaffected.
6) A bacterium inherits a mutation that renders its topoisomerase enzyme nonfunctional. What phenotype would you expect to see in this bacterium?
A) The cell would accumulate broken DNA because overwinding cannot be corrected, so the cell would be unable to replicate and would die.
B) The cell would accumulate supercoiled DNA, but otherwise it would be perfectly normal.
C) The cell would accumulate relaxed DNA, which would make DNA replication and cell division highly disorganized and lead to cell death.
D) The cell would accumulate relaxed DNA, but otherwise it would be perfectly normal.
E) The cell would be unaffected because bacteria have many different topoisomerases that are involved in replication.
7) How might a thermophilic bacterium use chromosome structure to protect against heat-induced DNA degradation?
A) It expresses excess amounts of SMC proteins that allow the DNA to more tightly condense during periods of high heat.
B) It can express a specialized topoisomerase that induces negative supercoiling, which provides additional chromosomal stability.
C) It expresses a specialized topoisomerase that induces positive supercoiling, which provides additional chromosomal stability.
D) It expresses enzymes that inhibit topoisomerase during high heat, which prevents DNA from unwinding and becoming susceptible to heat degradation.
E) It expresses helicase, an enzyme that nicks the DNA helix and allows it to assume a more stable conformation and thus to resist heat-induced degradation.
8) What is meant by the “beads on a string” model of chromatin?
A) The beads are the histones, and the string is the transcriptionally active DNA loops.
B) The beads are the nucleosomes, and the string is the linker DNA.
C) The beads are molecules of DNA polymerase that attach to the DNA string.
D) The beads are ribosomes, and the string is the mRNA that has been transcribed from active chromatin.
E) The beads are the heterochromatic regions that are tightly compacted, and the strings are euchromatic regions that are being actively transcribed.
9) Under normal cellular conditions, what is the diameter of the chromatin as it forms the solenoid structure?
A) 3 nm
B) 10 nm
C) 30 nm
D) 34 nm
E) 100 nm
10) A cell can form 10 nm chromatin fibers, but not 30 nm fibers. Which molecule has likely been removed or mutated in this cell?
E) SMC proteins
11) Which histone protein is not part of the core nucleosome structure?
12) Active transcription occurs in regions of chromatin loops that are located __________.
A) near the MARS
B) a large distance away from the MARS
C) within the linker DNA
D) within the telomeres
E) within the euchromatin and constitutive heterochromatin
13) Which type of chromosome has no p arms?