DNA REPLICATIONDNA, and in some cases RNA, is the primary source of heritable information.
The “Central Dogma”Replication
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Translation
DNA ReplicationAllows for heritability of genetic information.
Happens “Semi-conservatively”
Each strand of an old molecule serves as a template for the synthesis of a new strand.
The ReplisomeAll of the enzymes involved in replication function together.
Helicase: Topoisomerase: Opens the helix. Rotates the helix.
Ligase: Joins DNA fragments
Primase: Synthesizes RNA primer
DNA PolymeraseResponsible for the addition of new nucleotides to a growing strand.
Can only add nucleotides in the 5’ → 3’ direction.
Makes mistakes.
Directional Synthesis 5’→3’Polymerase can only make new strands in the 5’ → 3’ direction.
Leading strand: synthesized continuously in 1 piece.Lagging strand: synthesized discontinuously in multiple fragments, connected by ligase.
Okazaki FragmentsThe lagging strand is synthesized discontinuously, as a series of segments called Okazaki fragments
Proofreading and Repairing DNANuclease – an DNA cutting enzyme that cut outs (excised) damage DNA
Telomeres – repetitive DNA at the end of eukaryotic chromosome’s DNA molecule that protects genes from being eroded through repetitive replication