DNA Replication Activity 1 Primase makes RNA primer. Origin of replication Template strand RNA primer for fragment 1 2 DNA pol III makes Okazaki fragment 1. 3 DNA pol III detaches. Okazaki fragment 1 9) Only one strand of DNA is shown to the left: Which strand is shown? Leading or lagging strand? CIRCLE ONE 10) RNA primer is placed near the origin of replication site by an enzyme called ? 11) A. What enzyme catalyzes the synthesis of most of the DNA? Include number. B. (true/false) This enzyme adds new DNA nucleotides to preexisting nucleotides. C. What provides a place (3' OH end) for this enzyme to start making the complementary DNA strand? 12) What are the DNA fragments on the lagging strand called? RNA primer for fragment 2 Okazaki fragment 2 4 DNA pol III makes Okazaki fragment 2. 5 DNA pol I replaces RNA with DNA. 6 DNA ligase forms bonds between DNA fragments. Overall direction of replication 13) Which enzyme replaces the RNA primer with DNA nucleotides on the leading and lagging strands? Include number. 14) A phosphodiester bond is formed between nucleotides of the DNA fragments (e.g. Okazaki fragments) by what enzyme? 15) Compare and contrast the functions of DNA polymerase III and DNA polymerase I. 16) Which comes first removal of the RNA primer or DNA ligase joining the DNA fragments?
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- The template strand shown is 5' to 3'. Since DNA synthesis occurs in the 5' to 3' direction, the complementary strand synthesized will be 3' to 5'. Therefore, the strand being synthesized is the lagging strand. Step 2: Determine the enzyme that catalyzes the Show more…
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The process of DNA replication involves several key enzymes and molecules. One important element is the TATA box, which serves as a promoter for RNA polymerase. Another crucial component is telomerase, which helps to maintain the length of telomeres. Telomeres are repetitive sequences of DNA at the ends of chromosomes. During replication, the DNA strands separate at the replication fork, and a RNA primer is synthesized to provide a starting point for DNA synthesis. The leading strand is synthesized continuously in the 5' to 3' direction, while the lagging strand is synthesized in short fragments called Okazaki fragments. These fragments are later joined together by DNA ligase. DNA polymerase is the enzyme responsible for adding nucleotides to the growing DNA strand. It can only add nucleotides in the 5' to 3' direction, so the DNA strands are antiparallel. The process of DNA replication is semiconservative, meaning that each new DNA molecule consists of one original strand and one newly synthesized strand. Other enzymes involved in replication include helicase, which unwinds the DNA double helix, and topoisomerase, which relieves the tension caused by unwinding. SSBs (single-stranded binding proteins) help to stabilize the single-stranded DNA during replication. Exons are the coding regions of DNA that are transcribed into RNA. The RNA primer is eventually removed and replaced with DNA by the enzyme primase. Overall, DNA replication is a complex and highly regulated process that ensures the accurate duplication of genetic information.
Sri K.
The Central Dogma states in part that DNA makes proteins by the process of translation and that this protein makes DNA by the process of transcription. In order for the process of DNA replication to proceed, the supercoiled DNA must be relaxed by enzymes known as topoisomerases. The DNA helix must also be unwound/opened by helicases; then, this replicating fork must be further stabilized by single-strand binding proteins. The leading strand is elongated from a primer by the enzyme DNA polymerase. Elongation of the lagging strand is done in sections. Short primers, composed of RNA, are elongated. The short pieces of DNA that are added to the primers on this lagging strand are known as Okazaki fragments. The primers are degraded and the gaps are filled with DNA by the enzyme DNA polymerase. Enzymes, called ligases, then join the discontinuous pieces of DNA together. The hereditary code must be capable of variation because of genetic mutations. There are two major ways in which this is accomplished: one is by point mutations, which change a single nucleotide; the other results from chromosomal rearrangements, which alter the structure of the chromosome. Additionally, changes can be made by the action of mutagens. A particular polymerase's function is indicated in its name: e.g., a DNA dependent RNA polymerase is an enzyme that makes RNA, using DNA as a template. Using this nomenclature, primase, the enzyme that makes the primers on the lagging strand during replication, could be called a DNA dependent RNA polymerase. Another example is reverse transcriptase used by RNA viruses: reverse transcriptase should be called RNA dependent DNA polymerase.
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Why DNA replication includes leading and lagging strands
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