DNA Replication - Chapter 8.3 - 15 pts
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by Kathy Egbert
| 16 Questions
Note from the author:
Video clip and text explaining the process of DNA replication
Every cell needs its own complete set of DNA, and the discovery of the three-dimensional structure of DNA immediately suggested a mechanism by which the copying of DNA, or DNA replication, could occur. Because the DNA bases pair in only one way, both strands of DNA act as templates that direct the production of a new complementary strand. DNA replcation takes place during the S stage of the cell cycle.

The process of DNA replication is very similar in both eukaryotes and prokaryotes, but we will focus on eukaryotes.

During the S stage of the cell cycle, the DNA is loosely organized in the nucleus. Certain enzymes start to unzip the double helix at places called origins of replication. The double helix unzips in both directions along the strand. Eukaryotic chromosomes are very long, so they have many origins of replication to help speed the process. Other proteins hold the two strands apart.

The unzipping exposes the bases on the DNA strands and enables free-floating nucleotides to pair up with their complementary bases. DNA polymerases bond the nucleotides together to form new strands that are complementary to the original template strands.

The result is two identical strands of DNA. DNA replication is described as semiconservative because each DNA molecule has one new strand and one original strand.

DNA polymerase not only bonds nucleotides together, it also has a proofreading function. It can detect incorrectly paired nucleotides, clip them out, and replace them with the correct nucleotides. Uncorrected errors are limited to about one per 1 billion nucleotides.
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Last Name, First Name
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Class Period
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Date:
Functionalized Placeholder
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General Description box: Insert description of the process of DNA Replication and where it occurs
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#1 under Identify the Structures
A original strands of DNA
B backbone of DNA
C nitrogen bases
D new copied strand of DNA
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#2 under Identify the Structures
A phosphate groups
B deoxyribose sugars
C nitrogen bases
D covalent bonds
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#3 under Identify the Structures
A phosphate polymerase complex
B DNA polymerase complex
C deoxyribose sugar polymerase complex
D nitrogen base polymerase complex
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#4 under Identify the Structures
A original strand of DNA
B DNA backbone
C nitrogen bases
D new complimentary strand of DNA
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#1 under Process: The first step in replication is when enzymes unzip the DNA double helix in both directions at the same time.
True
False
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#2 under Process: Free-floating phosphates pair with the exposed nitrogen bases on both sides of the original strand.
True
False
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#2 under Process: Bases pair up quickly on the leading strand, however, the bases have to be filled in backwards on the lagging strand and so it takes longer to complete this half of the DNA strand.
True
False
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#2 under Process: DNA is copied from the 3' prime to the '5 prime end.
True
False
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#3 under Process: The DNA polymerase bonds the new nucleotides together to form the new strand which is bonded to one side of the original strand.
True
False
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#4 under End Result: Two identical strands of DNA are made. Each strand has one of the original strands and one of the new strands.
True
False
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#4 under End Result: Briefly describe what semiconservative means in relationship to the way DNA is copied.
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What are major functions that DNA polymerase performs?
A unzips the DNA strand and makes the new nucleotides
B proof reads the new DNA strands for errors and corrects them
C bonds the nucleotides together forming the new DNA strand
D A, B, and C
E A and B
F B and C
G A and C
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