DNA Lab



Name: ____________________________________ Date: ___________ Block: ___________DNA Structure, Function and Replication LabPart 1: DNA Structure and Replication Use your notes and pages 295-299 to answer the following questionsWhat three parts make up a nucleotide? _________________________________________ Where in eukaryotic cells is DNA found? _________________________________________Where in prokaryotic cells is DNA found? ________________________________________What is the significance of base pairing? __________________________________________________________________________________________________________________What makes up the "backbone" of the DNA molecule? ______________________________What part of a DNA molecule is responsible for the genetic code? _____________________What is the difference between purines and pyrimidines? _____________________________________________________________________________________________________Which nitrogen bases are purines? _____________________________________________Which nitrogen bases are pyrimidines? __________________________________________On DNA, a purine will always pair with a ________________________________________What type of bonds holds the DNA bases together? ________________________________How many hydrogen bonds link cytosine & guanine? ______ Adenine & Thymine? ______Why is DNA replication called semi-conservative? ___________________________________________________________________________________________________________________________________________________________________________________When and why does DNA need to replicate? _________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________DNA polymerase III synthesizes DNA by adding a nucleotide to the ______’ end of a pre-existing chain of nucleotides. What are Okazaki fragments? Why do they form? ____________________________________________________________________________________________________________________________________________________________________________________Complete the following strand of DNA by placing the letter of the correct nitrogenous base on the line provided5’?C?C?A?G?T?A?G?T?T?3’?????????????????????Part 2: Animations of DNA replication Watch the animations and answer the following questions THE FOLLOWING ANIMATION: How Nucleotides are added in DNA replication? List the enzymes (and other proteins) involved in the process of replication. _____________________________________________________________________________________________________________________________________________________________________________________________________________________How does replication start? Who prevents the unwound DNA from twisting back?_____________________________________________________________________________________________________________________________________________________________________________________________________________________Which enzyme is the key player in replication? What is this enzyme’s limitation? How is this limitation overcome? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________Why do the two strands of the helix have to be elongated by two slightly different mechanisms? _______________________________________________________________________________________________________________________________________________________________________________________________________Explain the elongation stage of replication – your answer should include a discussion of the leading strand, lagging strand, Okazaki fragments and RNA primer. _____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________WATCH THE FOLLOWING ANIMATION: DNA Replication Fork 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: ________________________________________________________________________________________________________________________________________How are Okazaki fragments on the lagging strand joined into one continuous strand?_______________________________________________________________________How do eukaryotes speed the process of replication – since they have multiple chromosomes that are very long? ____________________________________________What is the role of Helicase? ______________________________________________________________________________________________________________________What is the role of DNA polymerase I and polymerase III in DNA replication?_____________________________________________________________________________________________________________________________________________________________________________________________________________________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. 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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