#Question id: 2872
#Unit 2. Cellular Organization
Concerning disorders resulting from unstable expansion of tandem oligonucleotide repeats, which, if any of the following statements is false.
A) The expansions can occur in coding DNA in some cases, and in noncoding DNA in other cases.
B) The repeats are of a variable number of nucleotides (from three to six) in both coding DNA and noncoding DNA.
C) The expansions in noncoding DNA are generally much larger in size than those in coding DNA.
D) The expanded arrays in noncoding DNA always result in loss of function of the host gene or of a neighboring gene.
#Question id: 2873
#Unit 2. Cellular Organization
With reference to aberrant methylation of bases which of the following statements, if any, is false?
#Question id: 2874
#Unit 2. Cellular Organization
Match one item from numbered group A with a lettered item from group B.
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GROUP I |
GROUP II |
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1. Yeast artificial chromosomes |
a. They are more stable |
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2. Bacterial artificial chromosome |
b. It is very hard to construct |
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c. It is not so hard to construct |
|
|
d. They are unstable |
|
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e. are used to clone the DNA inserts up to 300kb |
|
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f. are used for cloning very large (1000-2000kb) DNA segments |
#Question id: 2875
#Unit 2. Cellular Organization
Which of the following statements is/are CORRECT from the following?
I. The chromosome of the small monkey DNA virus SV40 is a circular, double-helical DNA molecule of 5000 bp.
II. The phage Lambda genome is a linear single-stranded molecule in the virion particle.
III. Circular DNA molecules purified from both bacteria and eukaryotes are usually negatively supercoiled, having values of sigma of approximately –0.06.
IV. Prokaryotes have a special type I topoisomerase known as “DNA gyrase” that introduces, rather than removes, negative supercoils.
V. DNA disentanglement, generally catalyzed by a type II topoisomerase, is also required for a successful round of DNA replication and cell division in eukaryotes.
#Question id: 2876
#Unit 2. Cellular Organization
From the following set of statements regarding DNA topology, state whether each of the given statement is either True or False.
A. The two strands of cccDNA can be easily separated without any breakage of bonds.
B. Circular DNA molecules purified from bacteria and eukaryotes are usually negatively supercoiled.
C. Interwound writhe and spiral writhe are topologically different.
D. The organisms that live under extreme temperature conditions have been found to have positively supercoiled DNA.
E. Negative supercoils can be thought of as a store of free energy that aids in processes that require strand separation.
#Question id: 2877
#Unit 2. Cellular Organization
What is the superhelical density of a closed-circular DNA with a length of 4,200 bp and a linking number (Lk) of 374? What is the superhelical density of the same DNA when Lk = 412? Are these molecules negatively or positively supercoiled?
A. The molecule is getting negatively supercoiled.
B. The molecule is getting positively supercoiled.
C. The superhelical density is positive.
D. The superhelical density is negative.
Which of the combinations of the above statements are correct?