DNA Metabolism

In the Meselson-Stahl experiment, what was the composition of DNA molecules after E. coli cells grown in a 15N medium were transferred to a 14N medium and allowed to complete one round of replication?

What is the primary direction of DNA synthesis for a new strand, and what does this require at the growing end of the chain?

In E. coli DNA replication, what is the term for the short, discontinuously synthesized pieces of DNA on the lagging strand?

What are the two central requirements for all DNA polymerases to initiate DNA synthesis?

The 3' to 5' exonuclease activity found in most DNA polymerases provides which function?

Which E. coli DNA polymerase is the principal replication enzyme?

The processivity of the E. coli DNA polymerase III holoenzyme is dramatically increased by which component?

What is the primary function of the DnaA protein in the initiation of replication in E. coli?

The enzyme DNA ligase seals a broken phosphodiester bond in DNA. In E. coli, what molecule is used as the source of the AMP activating group for this reaction?

Termination of replication in the circular E. coli chromosome involves Tus protein binding to which specific sequences?

How does replication in eukaryotes differ from bacterial replication regarding origins of replication?

What is the primary role of the DNA repair system involving DNA photolyases?

The methyl-directed mismatch repair system in E. coli uses which mechanism to distinguish the template strand from the newly synthesized strand?

What is the function of the enzyme O6-methylguanine-DNA methyltransferase?

Which type of genetic recombination involves the exchange between any two DNA molecules that share an extended region of nearly identical sequence?

What is the key protein that promotes DNA strand invasion during homologous recombination in E. coli?

What is the name of the X-shaped crossover structure formed during homologous recombination where two DNA duplexes are joined?

In the context of immunoglobulin gene assembly, what is the function of the RAG1 and RAG2 proteins?

A bacterial strain with an altered gene for DNA polymerase I produces an inactive enzyme but is still viable, though it is abnormally sensitive to agents that damage DNA. What does this observation, made by John Cairns, suggest about DNA polymerase I?

The polymerization rate of E. coli DNA polymerase III is approximately 250 to 1,000 nucleotides per second. How does this compare to the polymerization rate of DNA polymerase I?

The E. coli DNA replication origin, oriC, consists of 245 base pairs. Which two types of sequence elements are of special interest within this region?

Which eukaryotic DNA polymerase is primarily responsible for synthesizing the short RNA/DNA primers for Okazaki fragments on the lagging strand?

The eukaryotic protein PCNA (proliferating cell nuclear antigen) is functionally and structurally analogous to which bacterial replication protein?

Base-excision repair is a pathway that corrects common DNA lesions. What is the first step in this repair process?

In the nucleotide-excision repair pathway in E. coli, the ABC excinuclease hydrolyzes two phosphodiester bonds. What is the size of the resulting excised DNA fragment?

What type of DNA damage is repaired by the error-prone translesion DNA synthesis (TLS) pathway, part of the SOS response in bacteria?

The process of DNA transposition is distinct from homologous and site-specific recombination because it usually involves what?

What is the primary role of homologous genetic recombination in bacterial cells?

The error rate of E. coli DNA replication is one mistake for every 10^9 to 10^10 nucleotides added. This high fidelity is achieved by a combination of mechanisms. What is the approximate error rate of the DNA polymerase polymerization reaction alone, before proofreading?

What is the function of the enzyme primase (DnaG protein) in E. coli DNA replication?