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DNA Replication. Beginning of DNA Replication Begins at Origins of Replication Two strands open forming Replication Forks (Y-shaped region) New strands.

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Presentation on theme: "DNA Replication. Beginning of DNA Replication Begins at Origins of Replication Two strands open forming Replication Forks (Y-shaped region) New strands."— Presentation transcript:

1 DNA Replication

2 Beginning of DNA Replication Begins at Origins of Replication Two strands open forming Replication Forks (Y-shaped region) New strands grow at the forks

3 Enzymes in DNA replication HELICASE unwinds parental double helix DNA POLYMERASE binds nucleotides to form new strands LIGASE joins Okazaki fragments and seals other breaks in sugar-phosphate backbone

4 Replication Step 1: HELICASE unzips DNA down the middle by breaking Hydrogen bonds.

5 Step 2: DNA POLYMERASE moves along the 2 strands and attaches base pair nucleotides to each original parent strand.

6 Step 3: Replication moves in only in the 5’ to 3’ direction. So, small DNA segments called OKAZAKI FRAGMENTS are made on the other strand.

7 Step 4: DNA LIGASE seals up all of the gaps in the DNA molecule, like the Okazaki fragments.

8 Result: 2 identical DNA molecules are formed from the original. http://highered.mcgraw- hill.com/olcweb/cgi/pluginpop.cgi?it=swf::535::535::/sites/dl/free/0072437316/1200 76/micro04.swf::DNA%20Replication%20Fork http://highered.mcgraw- hill.com/sites/0072943696/student_view0/chapter3/animation__dna_replication__qu iz_1_.html

9 Semi-conservative Model The two strands of the original molecule separate, and each acts as a template for a new complementary (matching) strand New DNA consists of 1 PARENTAL (original) and 1 NEW strand of DNA


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