Molec Cell Ch 6- DNA Repair & Rearrangement

A strand of DNA serves as a template for the synthesis of a _____________ antiparallel strand in the _______ direction.

complementary ; 5' to 3'

DNA polymerase also has 3' to 5' exonuclease activity- Proofreading ability.

If the wrong nucleotide is added during 5' to 3' DNA synthesis, DNA polymerase can remove it via its 3' to 5' exonuclease activity. Polymerase will then replace it with the correct nucleotide by resuming the 5' to 3' polymerase activity.

DNA can be altered by interacting with other molecules in the cell, UV radiation, etc.

______ is the loss of the purine bases, leaving behind an empty sugar-P behind.

Depurination

_________ is the removal of an amino group from cytosine, producing uracil.

Deamination

Mutations will be retained in ___ of the resulting daughter strands if they are not fixed before the next round of replication.

1/2

UV decontamination:

UV-induced thymine dimer= A cyclobutane ring forms between adjacent thymine bases. The joined thymines can not pair with adenines.

Mechanisms for DNA repair

Excision, re-synthesis, ligation