DNA Replication

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DNA Replication

• Double Helix explains how DNA can be copied so
  easily
• Each strand of the DNA double helix has all the
  information needed to reconstruct the other half
• Done by base pairing

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Eukaryotic Chromosomes

• DNA replication occurs at hundreds of places
• Replication proceeds in both directions until
  each chromosome is completely copied.
• Replication forks sites where separation and
  replication occur

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Duplicating DNA

• Replication process where DNA duplicates itself
  before a cell divides
• Replication ensures that each resulting cell will
  have a complete set of DNA.

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Duplicating DNA

• During DNA replication
• DNA molecule separates into two strands
• produces two new complementary strands following
  the rules of base pairing
• Base pairing Adenine with Thymine, Cytosine with
  Guanine
• Each strand of the double helix of DNA serves as
  a template for the new strand.

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New Strand
Original strand
Nitrogen Bases
Replication Fork
Replication Fork
DNA Polymerase
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How Replication Occurs

• DNA replication is carried out by enzymes that
  unzip a molecule of DNA.
• Hydrogen bonds between base pairs are broken and
  the two strands of DNA unwind.

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How Replication Occurs

• DNA polymerase enzyme that is involved in DNA
  replication
• Enzyme speeds up a reaction
• joins individual nucleotides to produce a DNA
  molecule
• proofreads each new
  DNA strand.

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Review Questions

• The first step in DNA replication is
• producing two new strands.
• Separating the strands
• producing DNA polymerase.
• correctly pairing bases.

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Review Questions

• 2. A DNA molecule separates, and the sequence
  GCGAATTCG occurs in one strand. What is the base
  sequence on the other strand?
• a. GCGAATTCG
• b. CGCTTAAGC
• c. TATCCGGAT
• d. GATGGCCAG

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Review Questions

• 3. In addition to carrying out the replication of
  DNA, the enzyme DNA polymerase also functions to
• a. unzip the DNA molecule.
• b. regulate the time copying occurs in the cell
  cycle
• c. proofread the new copies to minimize the
  number of mistakes
• d. wrap the new strands onto histone proteins.

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Review Questions

• The first step in DNA replication is
• producing two new strands.
• Separating the strands
• producing DNA polymerase.
• correctly pairing bases.

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Review Questions

• 2. A DNA molecule separates, and the sequence
  GCGAATTCG occurs in one strand. What is the base
  sequence on the other strand?
• a. GCGAATTCG
• b. CGCTTAAGC
• c. TATCCGGAT
• d. GATGGCCAG

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Review Questions

• 3. In addition to carrying out the replication of
  DNA, the enzyme DNA polymerase also functions to
• a. unzip the DNA molecule.
• b. regulate the time copying occurs in the cell
  cycle
• c. proofread the new copies to minimize the
  number of mistakes
• d. wrap the new strands onto histone proteins.