14. DNA Synthesis

Steps of DNA Replication

DNA Replication Made Easy

DNA Replication Animation - Super EASY

3.4.1 Explain DNA Replication

No. Topoisomerase relieves strain in the DNA ahead of the replication fork.

No. Primase links RNA nucleotides together to make a primer for DNA synthesis.

Review the details of DNA replication.

What enzyme joins Okazaki fragments?

Animation: DNA Replication: A Closer Look

Summary of DNA Replication

The helicase modifies the DNA in such a way as to eliminate the affinity between the two strands.

No. The two strands would come back together if they had the chance.

DNA polymerase follows the helicase so closely that there is no chance for the strands to come back together.

No. This is not true, especially on the lagging strand.

The helicase pushes the two strands so far apart that they have no chance of finding each other.

One of the strands is rapidly degraded, preventing the double helix from re-forming.

No. Both strands are maintained and used as templates for DNA replication.

Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming.

Once the DNA at the replication fork is unwound by helicases, what prevents the two strands from coming back together to re-form a double helix?

No. There is another term for the enzyme.

No. Primase synthesizes the RNA primer to initiate strand synthesis.

No. Ligase links segments of DNA together.

No. Helicases are responsible for unwinding the DNA helix to allow replication.

When this enzyme has done its job, the DNA should be "equal" to what it was prior to unwinding.

The unwinding of DNA at the replication fork causes twisting and strain in the DNA ahead of the fork, which is relieved by an enzyme called __________.

No. Ribosomes are the sites of polypeptide synthesis.

No. Messenger RNA plays a role in polypeptide synthesis.

No. Ligase is used for joining pieces of DNA together.

Remember that this question is only concerned with DNA replication.

Which of the following components is required for DNA replication?

No. Nucleases cut DNA&mdash;for example, as part of nucleotide excision repair.

No. Primase synthesizes the RNA primer to initiate leading and lagging strand synthesis.

No. Upon encountering the RNA primer, DNA polymerase III falls off the DNA and is replaced by DNA polymerase I.

No. Ligase links completed Okazaki fragments together.

There are several enzymes that can add nucleotides to DNA. .

The removal of the RNA primer and addition of DNA nucleotides to the 3' end of Okazaki fragments in its place is carried out by __________.

During DNA replication, the enzyme ___________, catalyzes the elongation of new DNA by adding, to the 3' end of the previous nucleotide, new nucleotides that are complementary to a DNA template.

Which of the following enzymes breaks the hydrogen bonds between the DNA strands?

DNA Replication

Helicase - relieves tension of supercoiling by breaking and rejoining ahead of fork

Primase - provides short stretch of RNA at initiation of strand synthesis

Polymerase – synthesizes new strand of DNA while using old strand of DNA as a template.

DNA ligase - joins 3’-OH to 5’-phosphate to seal adjacent DNA nucleotides.

Which of the following enzyme-function matches is incorrect?

Ligase assembles nucleotides into Okazaki fragments. Then polymerase joins these fragments together into a DNA strand.

No. Ligases link segments of DNA together.

The two strands of DNA separate, and nuclease enzymes digest one strand. Then DNA polymerase synthesizes two new strands out of the old ones.

No. Neither of the strands is destroyed during replication.

The two strands separate, and each one receives a complementary strand of RNA. Then this RNA serves as a template for the assembly of many new strands of DNA.

No. However, RNA is used as a primer for DNA synthesis.

Ligase separates the two strands of the DNA double helix. Then DNA polymerase synthesizes the leading strand and primase synthesizes the lagging strand.

No. Ligase links DNA segments together, and DNA polymerase is responsible for the synthesis of both the leading and the lagging strands.

Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates.

Which one of the following statements regarding DNA replication is correct?

Which of the following enzymes is responsible for removing RNA primers and replacing them with DNA?

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1. Introduction to Biology

2. Chemistry

3. Water

4. Biomolecules

5. Cell Components

6. The Membrane

7. Energy and Metabolism

8. Respiration

9. Photosynthesis

10. Cell Signaling

11. Cell Division

12. Meiosis

13. Mendelian Genetics

15. Gene Expression

16. Regulation of Expression

17. Viruses

18. Biotechnology

19. Genomics

20. Development

21. Evolution by Natural Selection

22. Evolution of Populations

23. Speciation

24. History of Life on Earth

25. Phylogeny

26. Prokaryotes

27. Protists

28. Plants

29. Fungi

30. Overview of Animals

31. Invertebrates

32. Vertebrates