| A | B |
|---|
| phage | a virus that infects bacteria |
| double helix | the form of native DNA, referring to its two adjacent polunucleotide strands wound into a spiral shape |
| semiconservative model | type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand |
| origins of replication | site of where the replication of a DNA molecule begins |
| replication fork | a Y-shaped region of a replicating DNA molecule where new strands are growing |
| DNA polymerase | an enzyme that catalyzes the elongation of new DNA at a replication fork by the addition of new necleotides to the existing chain |
| leading strand | the new continuous complementary DNA strand synthesized along the template strand in the mandatory 5'-3' direction |
| DNA ligase | a linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of a new DNA fragment to the 5' end of a growing chain |
| primer | a polynucleotide with a free 3' end, bound by complementary base pairing to the template strand, that is elongated during DNA replication |
| primase | an enzyme that joins RNA nucleotides to make the primer |
| helicase | an enzyme that untwists the double helix of DNA at the replication forks |
| single-strand binding protein | during DNA replication, molecules that line up along the unpaired DNA strands, holding them apart while the DNA strands serve as templates for the sunthesis of complementary strands of DNA |
| lagging strand | a discontinuously synthesized DNA strand that elongates in a direction away from the replication fork |
| mismatch repair | cellular process that uses special enzymes to fix incorrectly paired nucleotides |
| nuclease | an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids |
| excision repair | mechanisms that remove the damaged nucleotide replacing it with an undamaged nucleotide complementary to the nucleotide in the undamaged DNA strand |
| telomerase | enzyme that catalyzes the lengthening of telomeres. The enzyme includes a molecule of RNA that serves as a template for new telomere segment |
