Biochemistry ACS Exam Questions and Answers

Biochemistry ACS Exam Questions and Answers Helicase Ans- Catalyzes ATP -dependent unwinding of DNA double helices What is the helicase in E. Coli? Ans- DNAB Single -Stranded Binding Protein Ans- Binds to unwound strands of DNA to prevent reannealing DNA Polymerase Ans- Enzyme responsible for DNA replication Uses ssDNA as a template and makes a complimentary st rand by polymerizing deoxynucleotides Synthesis in 5' to 3' direction List the DNA polymerases in E. Coli Ans- Pol I, II, III DNA pol I Ans- Removes RNA primers and fills the gaps, proofreads DNA pol II Ans- DNA repair enzyme expressed in response to DNA damage DNA pol III Ans- Using parental DNA as a template, synthesizes new DNA strand by adding nucleotides to an RNA primer or a pre -existing DNA strand List the DNA polymerases in eukaryotes Ans- α, β, δ, ε, γ α polymerase Ans- Initiation of nuclear DNA replication β polymerase Ans- DNA repair δ polymerase Ans- Principal polymerase in leading and lagging strand sythesis, highly processive ε polymerase Ans- Leading and lagging strand synthesis , sensor of DNA damage, checkpoint control γ polymerase Ans- Mitochondrial DNA replication RNAse H Ans- A nuclease that specifically degrades RNA chains in DNA in eukaryotes (DNA Poly I in prokaryotes) DNA Ligase Ans- Seals nicks in dsDNA Telomerase Ans- Adds telomeres to the ends of chromosomal DNA, RNA -dependent DNA polymerase (has its own RNA primer) Semi -conservative model Ans- One parent strand and one newly synthesized strand