Recap  The Structure of DNA  A bonds with _______  G bonds with _______  What is the backbone made up of?  Base pairing = each strand of the double helix has all the information needed to reconstruct the other half.

Helicase  DNA is a double helix, how does it split to replicate?  -  Unwinds the DNA strands  -

Semi-Conservative Replication --

Replication  -  A free nucleotide has 3 phosphates, polymerase removes 2 phosphates, which provides the energy to join a nucleotide to a growing DNA strand.  -

 Each carbon in nucleotides is numbered  At one end is an unbonded 5’ Carbon and on the other end is an unbonded 3’ Carbon  -

Okazaki FragmentsOkazaki Fragments  The second side is put together in sections  -

Remember!  When it reaches an A : a T is added  When it reaches a G : a C is added  -

Checking For MistakesChecking For Mistakes  Sometimes the wrong base gets added, some get lost, or extras are added  -  -, 1,000 bases per second, mistakes are INEVITABLE  -

DNA Repair MechanismsDNA Repair Mechanisms  -  If mechanisms failed, a mutation results  Permanent change in the DNA sequence  Depending on the mutation survival is limited

Cloning  -  Types of cloning:  Reproductive Cloning  Somatic Cell Nuclear Transfer  Therapeutic Cloning

Reproductive CloningReproductive Cloning  A ball of cells can be grown from a fertilized egg in a petri dish  If divided into two, each half will develop an embryo  -

Somatic Cell Nuclear Transfer  Adult cloning  -  Removes the nucleus from an unfertilized egg, then inserts a nucleus from an adult animal cell  Example: Dolly the sheep!