DNA Rep

How to Use This In-Class Guide

  • Follow along with the slides and take notes.

Learning Objectives

  • 9.1 Explain the molecular basis of DNA replication.

  • 9.2 Describe how DNA is proofread during replication.

Pre-Class Review

  • 1. Can you label the parts of a DNA molecule? (Note: not all terms will be used)

    • a. Phosphate group

    • b. Deoxyribose sugar

    • c. Ribose sugar

    • d. Nucleotide

    • e. Pyrimidine

    • f. Purine

    • g. Nitrogenous base

    • h. Hydrogen bond

    • i. 5’ end

    • j. 3’ end

    • k. Ionic bond

DNA Replication: Week 9 Tuesday

In-Class Guide BISC207

Instructor: Dr. DeVito

Questions and Applications

  • 2. A bacterium has a gene mutation that resulted in the helicase protein not functioning properly. Which of the following will be most affected by this mutation?
    a. The ability to stabilize DNA
    b. The ability to unwind DNA
    c. The ability to relieve strain on DNA
    d. The ability to synthesize RNA primers
    e. The ability to fix DNA errors

  • 3. Which statement is true?
    a. DNA polymerase adds nucleotides to the 5’ end of DNA
    b. DNA replication requires energy
    c. Ribose sugars are added to new DNA strands
    d. DNA polymerase is always 100% accurate

Group Activity

  • 4. Work in your groups to complete the following table.

    • It is recommended that each person take 2 proteins, and then share with the group to complete the table.

    • You may want to use your pre-class guide as a reference.

Application Activity

  • 5. Sketch DNA replication on the provided template using the following steps.

    • Be sure to include the machinery you covered in the table above.

    • Do not show a single-sided bubble; show the whole replication bubble!

    • a. Opening of the double helix

    • b. Stabilization of the single strands

    • c. Relieving of the twisting forces downstream on the double helix

    • d. Addition of an RNA primer

    • e. Extension of the leading strand

    • f. Extension of the Okazaki fragments

    • g. Replacement of the RNA primer

    • h. Joining of Okazaki fragments

  • 6. UV damage can cause the formation of a _ bond between thymine bases on the same strand of DNA.

    • a. How does this impact the shape of the double helix?

  • 7. ____ __ is capable of proofreading as it synthesizes the new strand of DNA.

    • It does this by ___ the incorrect base.

Repair Mechanisms

  • 8. Mismatch repair occurs when a protein called detects a mismatched base, removes it and the surrounding bases, and then _ __ adds new complementary bases.

Lagging Strand Issues

  • 9. Lagging strand problems:

    • The space between the end of the chromosome and the last primer is not replicated. As a result, the new chromosome is (shorter/longer) .

    • a. These ends of the chromosomes are called .

    • b. What would happen if you went through multiple rounds of replication and could not replicate the ends?

Telomeres

  • 10. Telomeres are extended back to their original length by the protein called ___.

    • This protein has its own internal RNA _.

Telomere Length and Cell Division

  • 11. How does telomere length correspond to the number of divisions a cell is capable of?

Questions

  • 12. What questions do you still have?