Name: ____________________________________ Date: ___________ Block: ___________
DNA Structure, Function and Replication Lab
Part 1: DNA Structure and Replication
Use your notes and pages 295-299 to answer the following questions
1. What three parts make up a nucleotide? _________________________________________
2. Where in eukaryotic cells is DNA found? _________________________________________
3. Where in prokaryotic cells is DNA found? ________________________________________
4. What is the significance of base pairing? _________________________________________
_________________________________________________________________________
5. What makes up the "backbone" of the DNA molecule? ______________________________
6. What part of a DNA molecule is responsible for the genetic code? _____________________
7. What is the difference between purines and pyrimidines? ____________________________
_________________________________________________________________________
8. Which nitrogen bases are purines? _____________________________________________
9. Which nitrogen bases are pyrimidines? __________________________________________
10. On DNA, a purine will always pair with a ________________________________________
11. What type of bonds holds the DNA bases together? ________________________________
12. How many hydrogen bonds link cytosine & guanine? ______ Adenine & Thymine? ______
13. Why is DNA replication called semi-conservative? _________________________________
_________________________________________________________________________
_________________________________________________________________________
14. When and why does DNA need to replicate? ______________________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
15. DNA polymerase III synthesizes DNA by adding a nucleotide to the ______’ end of a preexisting chain of nucleotides.
16. What are Okazaki fragments? Why do they form? __________________________________
_________________________________________________________________________
_________________________________________________________________________
17. Complete the following strand of DNA by placing the letter of the correct nitrogenous base on
the line provided
5’
C
C
A
G
T
A
G
T
T
3’
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Part 2: Animations of DNA replication
Watch the animations and answer the following questions
http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html
WATCH THE FOLLOWING ANIMATION: How Nucleotides are added in DNA replication?
18. List the enzymes (and other proteins) involved in the process of replication.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
19. How does replication start? Who prevents the unwound DNA from twisting back?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
20. Which enzyme is the key player in replication? What is this enzyme’s limitation? How is
this limitation overcome? __________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
______________________________________________________________________
21. Why do the two strands of the helix have to be elongated by two slightly different
mechanisms? ___________________________________________________________
______________________________________________________________________
______________________________________________________________________
22. Explain the elongation stage of replication – your answer should include a discussion of
the leading strand, lagging strand, Okazaki fragments and RNA primer. ______________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
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WATCH THE FOLLOWING ANIMATION: DNA
Replication Fork
23. Draw a picture of the replication fork at the end of the video. Make sure to label all the
components.
Define the function of each of the components listed in the diagram above:

Helicase: __________________________________________________________________
_________________________________________________________________________

Leading Strand: ____________________________________________________________
_________________________________________________________________________

DNA polymerase III: _________________________________________________________
_________________________________________________________________________

Lagging Strand: ____________________________________________________________
_________________________________________________________________________

DNA polymerase I: __________________________________________________________
_________________________________________________________________________

RNA primer: _______________________________________________________________
_________________________________________________________________________

RNA primase: _____________________________________________________________
_________________________________________________________________________

DNA ligase: _______________________________________________________________
_________________________________________________________________________
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24. How are Okazaki fragments on the lagging strand joined into one continuous strand?
_______________________________________________________________________
25. How do eukaryotes speed the process of replication – since they have multiple
chromosomes that are very long? ____________________________________________
26. What is the role of Helicase? _______________________________________________
_______________________________________________________________________
27. What is the role of DNA polymerase I and polymerase III in DNA replication?
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
28. What is the role of DNA Ligase in DNA replication and why is it so important to the
process? _______________________________________________________________
_______________________________________________________________________
_______________________________________________________________________
Part 3: DNA Replication (the whole picture)
Watch the animations and answer the following pop quiz questions.
http://www.learnerstv.com/animation/animation.php?ani=169&cat=Biology
Pop Quiz: Answer the following pop quiz questions that follow the video above.

Which biomolecule is the carrier of hereditary information?

Which of these models best fits the correct model postulated by Watson & Crick?

What type of molecule is the primer (in blue)?

In what direction is DNA synthesized?
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