Transparency 11A

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DNA Replication (Sect 11.3) Objectives

• Describe the structure and function of DNA and
  its role in the process of DNA replication.

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The Template Mechanism

• What is a template?

• Each strand of the double helix acts as a
  template due to complimentary base pairing.

• The process of copying the DNA molecule is called
  DNA replication.

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DNA Replication

1. The two strands of the double helix separate.
2. Free nucleotides line up one at a time across
   from the template strand.
3. Complimentary base-pairing dictates how the
   nucleotides line up.
4. Enzymes called DNA polymerases link the
   nucleotides together.

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DNA replication

• The process of copying DNA
• Sequence of bases on 2 strands complementary
• Helicase breaks H-bonds untwist Double Helix
• DNA Polymerase pairs free nucleo. to open bases.
• Occurs simultaneously _at_ many pts. along strand of
  DNA.
• 2 identical strands.

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DNA Synthesis

• DNA copy Parent DNA New DNA strand.
• Parent strand acts as a template for the new
  strand.

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Transparency 11A-3
1. What do the yellow strands of DNA represent?
new DNA strands
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Transparency 11A-4
2. What will the two daughter DNA molecules
consist of?
Each consists of one original (parent) strand
and one new strand.
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DNA Replication
New DNA molecule
Original DNA Strand
Free Nucleotides
New DNA molecule
New DNA Strand
Original DNA
Original DNA Strand
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DNA Replication Video
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DNA Replication Real-Time Animation
www.dnai.org
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DNA Replication A Review

• The existing strands of DNA serve as a template
  during replication.

• Because of complimentary base pairing, DNA can
  replicate itself with great accuracy.

• During replication, the DNA strand separates and
  nucleotides pair with their complimentary bases.
  DNA polymerases then bond the paired nucleotides.

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Question 1
Why is DNA replication important to cell
division?
Answer
Without DNA replication, new cells would have
only half the DNA of their parents. Species could
not survive and individuals could not grow or
reproduce successfully.
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Question 2
What serves as the template for the production of
new DNA molecules?
Answer
The existing DNA strands.
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Question 3
Which of the following are instrumental in
bonding together the nucleotides of the new
strand?
A. catalase
B. purines
C. nucleotides
D. DNA polymerase
The answer is D.
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DNA Replication (Sect 11.3) Objectives

• Describe the structure and function of DNA and
  its role in the process of DNA replication.