Wwu4h 4 apply concepts give an example of an

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W¤}“}wu¢4h 4. Apply Concepts Give an example of an incorrect base pairing. dggcaf_8[dgk] 5. Identify Name two proteins that are important in DNA replication. SECTION 2
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Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Reader 138 DNA, RNA, and Proteins Name Class Date Replication of DNA continued DNA REPLICATION IN PROKARYOTIC CELLS Remember that the DNA in cells is packaged in the form of chromosomes . All cells have chromosomes, but prokaryotes and eukaryotes replicate their chromosomes in different ways. Prokaryotic cells usually have a single, circular chromosome. It is a closed loop attached to the inner cell membrane. Replication starts at one place along the chromosome. Two replication forks begin at that point. Replication proceeds in opposite directions until the two replication forks meet on the opposite side of the chromosome. At that point, the entire DNA molecule has been copied, as shown in the figure below. Original DNA New DNA Original DNA Replication forks Prokaryotic DNA Eukaryotic DNA Replication forks New DNA Replication “bubble” In prokaryotic cells, each circular chromosome has two replication forks. In eukaryotic cells, each linear chromosome may have many replication forks. DNA REPLICATION IN EUKARYOTIC CELLS Most eukaryotic cells contain several chromosomes. They stretch out in straight lines, and contain both DNA and protein. DNA replication in eukaryotic chromosomes starts at several sites at the same time. This process forms the replication “bubbles” shown above. The bubbles get larger as more of the DNA is copied. Eventually, all the bubbles on a particular chromosome meet, leaving two identical DNA molecules. READING CHECK 6. Describe At how many points on a prokaryotic chromosome does DNA replication begin? dggcaf_8[dgk]j8 7. Compare How does the shape of a prokaryotic chromosome compare to the shape of a eukaryotic chromosome? SECTION 2
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Copyright © by Holt, Rinehart and Winston. All rights reserved. Interactive Reader 139 DNA, RNA, and Proteins Name Class Date Section 2 Review SECTION VOCABULARY DNA helicase an enzyme that unwinds the DNA double helix during DNA replication DNA polymerase an enzyme that catalyzes the formation of the DNA molecule DNA replication the process of making a copy of DNA 1. Identify Give two functions of DNA polymerase in DNA replication. 2. Describe Fill in the blanks in the flowchart below to show how DNA replication occurs. separate the two complementary strands of DNA, forming . At the , DNA polymerases add bases to each strand, forming two new DNA molecules. bases continue to be added until the entire DNA strand has been copied. Two new DNA molecules form. Each is to the other and to the original DNA molecule. 3. Compare Give one difference and one similarity between DNA replication in eukaryotic cells and DNA replication in prokaryotic cells.
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  • Fall '19
  • DNA, Holt, Rinehart

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