DNA Replication

The structure of DNA consists of two polynucleotide strands wrapped around each other in a double helix Figure 10.3C Twist 1 chocolate coat, Blind (PRA)

Hydrogen bonds between bases hold the strands together –Each base pairs with a complementary partner –A pairs with T –G pairs with C

Three representations of DNA Figure 10.3D Ribbon modelPartial chemical structureComputer model Hydrogen bond

In DNA replication, the strands separate – Enzymes assemble the new strands – With each strand serving as a template DNA REPLICATION 10.4 DNA replication depends on specific base pairing Parental molecule of DNA Figure 10.4A Both parental strands serve as templates Two identical daughter molecules of DNA Nucleotides A A

Untwisting and replication of DNA Figure 10.4B

DNA replication begins at specific sites 10.5 DNA replication: A closer look Figure 10.5A Parental strand Origin of replication Bubble Two daughter DNA molecules Daughter strand

Each strand of the double helix is oriented in the opposite direction Figure 10.5B 5 end3 end 5 end P P P P P P P P

How DNA daughter strands are synthesized 5 end P P Parental DNA Figure 10.5C DNA polymerase molecule Daughter strand synthesized continuously Daughter strand synthesized in pieces DNA ligase Overall direction of replication 5 3 The daughter strands are identical to the parent molecule