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17. 18. 19. Write in planner!. You need: A pencil DNA note sheets and reading sheets Today: DNA replication. HW: Due Fri. 01/18/08 Write a results section and conclusion section for the Neurospora experiment Must be typed!. What makes up the DNA backbone?.
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17 18 19 Write in planner! • You need: • A pencil • DNA note sheets and • reading sheets • Today: • DNA replication HW: Due Fri. 01/18/08 Write a results section and conclusion section for the Neurospora experiment Must be typed!
Which parts of the nucleotides are connected to make one strand (half) of DNA? • Which parts of the nucleotides connect the two strands (halves) of DNA? • What type of bond connects the two strands together?
What types of molecules are necessary for DNA replication? • Which enzyme unwinds DNA? • Where does it unwind the DNA? • Which enzyme connects new nucleotides to the DNA during replication?
Complementary base pairing • If one strand of DNA has the following sequence, CTAATGT GATTACA What is the base sequence (order of nucleotides) for the complimentary strand?
Enzymes in DNA replication • Enzymes are proteins that act as machines in the cell
Enzymes in DNA replication • Enzymes are proteins that act as machines in the cell • 2 enzymes do the work of DNA replication: • Helicase is responsible for separating the 2 strands of DNA • DNA Polymerase is responsible for adding on new Nucleotides. We will replicate (copy) our DNA molecule in class to produce 2 new identical DNA molecules
Helicase • Helicase unwinds and separates the 2 strands of DNA so that each strand may be copied. • Helicase breaks the hydrogen bonds between the bases of each strand. Hydrogen Bonds
DNA Polymerase • DNA Polymerase adds on the complimentary bases to the new strands of DNA • DNA Polymerase makes bonds between the phosphate and the deoxyribose sugar of the nucleotides. T A Phosphate-Sugar bond
DNA replication C T A G G T T C C
Replication in Action • Replication occurs simultaneously at multiple places along a DNA strand. • 1 chromosome is about 80 million base pairs long. • Replication is as fast as 50 base pairs a second! Nobel e-Museum: DNA – leading strand replication Nobel e-Museum: DNA – lagging strand replication