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img007 - c The reaction tube with DNA#1 DNA#2 has two DNA...

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Unformatted text preview: c. The reaction tube with DNA #1 + DNA #2 has two DNA Chapter 6 1 15 6-25. The figure showshotghsq’afng/soTDT A being replicated in the same direcfign relative to the replication fork. We now know that each replication fork has a lagging strand and a leading xx: strand because DNA polymerasefoyly catalyzesthe,additioniof nucleotides to thd:3>end of the growingchain. Watson and Crick's figurgélso makes it seem as i W” _ h , , fDNB replication happens spontaneously without the participation of any of the many proteins that are now known to be involved in the process (Fig. 6.18). In spite of these simplifications, this drawing was one of the most influential in the history of modern biology. Watson and Crick' s simplificmtion madeit intuitively obvious how double helical DNA could be passed from one generation to the next. This was very important in convincing scientists of the time that their model was valid. 6-26. In order to unlock the intertwined helices, you must break both strands of one of the intertwined molecules. The unbroken strand can then pass through the break in the other DNA molecule. The broken helix must then be rejoined. This breakage/rejoining is mediated by topoisomerase. 6-27. Remember that DNA polymerase requires a primer supplying a free 3' end so that nucleotides can be added to the growing new strand, a single-stranded template DNA to copy and a source of dNTPs. The dNTPs have been already added to the reaction tubes. 21. The reaction tube with DNA #1 + DNA #3 has two DNA strands. In order for DNA polymerase to work these DNAs must form a region of double helical DNA - the two strands must have some complementary base sequences. They can pair with each other as follows: 5' CTACTACGGATCGGG 3' (#1) 3' ...TGACCGATGA 5' (#3) No new DNAs will be formed. Although the primers have annealed and each primer has a free 3 ’ end, there is no template for the DNA polymerase. See also part (1 below. The reaction tube with DNA #2 + DNA #3 has no regions of DNA complementarity so no new DNAs will be formed. See also part d below. strands. In order for DNA polymerase to work these DNAs must form a region of double helical DNA - the two strands must have some complementary base sequences. They can pair with each other as follows: 5' CTACTACGGATCGGG 3' (#1) 3' TGCCTAGCCCTGACC 5' (#2) In this configuration both ...
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