Concept explainers
To determine: How the synthesis of the leading strand be affected if DNA pol I was non-functional and also point out the location of function of DNA pol I in the given figure.
Concept introduction:
DNA is a double-stranded molecule. During its replication, the two parent strands unwind, and each strand acts a template for the synthesis of a new strand. DNA polymerase enzyme adds
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- Review Figures 8.12 and 8.13. In cells, the primers for DNA synthesis are short strands of RNA, so each newly-synthesized strand of DNA has a segment of RNA al its 5 end. As replication proceeds, DNA polymerases remove these RNA segments and fill in the resulting gaps with DNA. However, the gaps at the very 5 ends of the new strands cannot be filled in with DNA. Why not? DNA replication leaves exposed about 100 nucleotides al the 5 end of each template strand, and these single-stranded ends are removed. What are the effects of this "end problem" on a cell's DNA as it continues to divide? FIGURE 8.12 DNA replication. Green arrows show the direction of synthesis for each strand. The Y-shaped structure where the DNA molecule is being unwound is called a replication fork. FIGURE 8.13 Discontinuous synthesis of DNA. This close-up of a replication fork shows that only one of the two new DNA strands is assembled continuously. The other is assembled in short segments.arrow_forwardDNA: 5’-CTCTACTATAAACTCAATAGGTCC-3’ Draw a box around the sequence where RNA polymerase will bind to the DNA. What is this sequence called? Will transcription start at this sequence, to the left of this sequence (“upstream”) or, to the right of this sequence (“downstream”)? Draw a small arrow above the DNA strand where transcription will begin. Which DNA strand will RNA polymerase transcribe? Highlight this strand with your highlighter. (Hint: RNA pol is similar to DNA pol because it can only make new RNA in the 5’ to 3’ direction. Draw in an arrow to show the direction that RNA polymerase will move along the DNA strand.arrow_forwardExamine the following DNA sequence (only one strand is shown). The shown strand will be referred to as Strand 1. The complementary strand will be referred to as Strand 2: 5’ TTTAAGCCGTACCGATATAATGTAAGGCGAGCTTGACCGTCTTGGGCATCATA 3’ There is an eleven (11) base pair sequence that serves as a replication origin. Write below the most likely 11 nucleotides on this strand that serve as the replication origin. Think carefully about base pairing.arrow_forward
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