DNA Replication and Telomeres

Understand the roles of DNA Polymerase I and III in prokaryotic DNA replication, including their functions in synthesis, proofreading, and primer removal.
Describe the replication fork, including the key proteins (helicase, primase, SSB, etc.) and processes involved in leading and lagging strand synthesis, including Okazaki fragment formation.
Compare prokaryotic and eukaryotic replication, highlighting similarities (bidirectional replication, primers) and differences (multiple origins, chromatin structure, telomeres) between the two systems.
Explain telomere maintenance, describing the structure of telomeres, the role of telomerase in replication, and its implications for aging and cancer.
Outline eukaryotic initiation, summarizing the steps in eukaryotic replication initiation, including ORC complex, licensing factors (Cdc6, MCM), and polymerase switching (Pol α, δ, ε).
Analyze chromosome completion, contrasting the termination of replication in circular (prokaryotic) and linear (eukaryotic) DNA, including decatenation and telomere elongation.

Enzyme responsible for synthesizing new DNA strands.
Discovered by Arthur Kornberg in 1958.
Enzyme from E. coli capable of in vitro DNA synthesis
Polymerase I (Pol I): A single polypeptide of 109,000 daltons.
- DNA Pol I mutants are viable and make DNA at normal rates.
- Not the major enzyme for DNA replication in vivo.
Four additional polymerases exist; the most important for replication:
- DNA Pol III: Key enzyme for synthesis of DNA from RNA primers.
- DNA Pol II: Involved in repair.

The α phosphate of a nucleotide triphosphate is used to combine properly base-paired nucleotides.

Large complex protein composed of 10 different polypeptides (> 600 kDa).
Core polymerase composed of three subunits: α, ε, θ
- α: Active site for nucleotide addition in the 5’-3’ direction.
- ε: 3’-5’ exonuclease (