The segment of DNA shown in Figure 13.4 has restriction sites I and II, which cr
ID: 99985 • Letter: T
Question
The segment of DNA shown in Figure 13.4 has restriction sites I and II, which create restriction fragments A, B. and C. Which of the gels produced by electrophoresis shown below best represents the separation and identity of these fragments? What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized? A) Helicases and single-strand binding proteins work at the 5' end. B) DNA ligase works only in the 3' -5' direction. C) DNA polymerase can join new nucleotides only to the 3' end of a preexisting strand. D) The origins of replication occur only at the 5' end. In a nucleosome, the DNA is wrapped around A) a thymine dimer B) histones C) ribosomes. D) polymerase molecules. Which of the following sequences in double-stranded DNA s most likely to be recognized as a cutting site for a restriction enzyme? A) ACCA TGGT B) GGCC CCGG C) AAAA TTTT D) AAGG TTCCExplanation / Answer
Q1: The answer is C (-C A B+)
The fragments move from negative charge to a positive charge based on their respective sizes. The fragments A, B, C are of variable size hence migrate differently. Bigger fragments migrate slower than the shorter fragments. The fragment C is the largest and so it moves slower than the other shortest fragments A followed by B.