30 Questions
What is the consensus sequence of the 9 bp DnaA boxes in oriC?
5’-TTATCCACA-3'
What is the sequence of the 13-bp AT-rich region where initiation of replication commences?
5’-GATCTNTTTNTTT-3'
Which protein binds to the unwound region in DNA replication and is facilitated by DnaC?
DnaB
What is the process called that denatures the DNA in the 13-mer sequences during replication?
Unzipping
Which protein prevents the renaturation of single-stranded DNA?
Single-strand binding (SSB) protein
What relieves the torsional stress caused by the unwinding of DNA during replication?
DNA gyrase
What are the three models of DNA replication?
Conservative, semi-conservative, dispersive replication
Who showed that DNA replication is semiconservative?
Matthew Meselson and Franklin Stahl (1958)
What are the four steps involved in the general mechanism of DNA replication?
Replication Fork Formation, Primer binding, Elongation, Termination
How does DNA replication occur in terms of continuity and discontinuity?
Semi-discontinuously: one strand is copied continuously, while the other is copied discontinuously in portions
What happens during Elongation in DNA replication?
New DNA strands are formed by complementary base pairing
What is the junction of the unwound molecules called in a replication bubble?
Replication fork
How does leading-strand synthesis proceed?
Continuously in the 5' to 3' direction through RNA primers
What is the nature of lagging-strand synthesis?
Discontinuous in the 5' to 3' direction with the formation of Okazaki fragments
How are Okazaki fragments eventually linked together?
Through later linkage after being synthesized discontinuously
Explain the Watson-Crick base-pairing during DNA replication.
A pairs with T (2xH-bonds) and G pairs with C (3xH-bonds)
In which direction does the phosphodiester bond formation occur during DNA replication?
In the 5' to 3' direction
List the three processes involved in DNA replication on prokaryotic cells.
- Preparation and priming the DNA for replication
- DNA polymerization
- Termination of replication
What is the function of DNA gyrase in DNA replication in prokaryotic cells?
Supercoiling
Which DNA polymerase in prokaryotic cells is involved in new strand elongation?
DNA polymerase III
What is the role of the 𝜀 (epsilon) subunit in DNA polymerase III?
3'→5' exonuclease activity
Name the protein responsible for binding to single-stranded DNA in prokaryotic DNA replication.
SSB (single-strand binding)
What is the function of DnaB (helicase) in prokaryotic DNA replication?
DNA unwinding
Which DNA polymerase in prokaryotic cells is involved in primer excision and filling the gaps?
DNA polymerase I
What cleaves the flap structure at the Okazaki fragments during DNA replication?
Endonucleases (such as Fen1)
What seals the gap in DNA after removal of the flap structure during DNA replication?
DNA ligase I
Why is the RNA primer sequence at the 3′-hydroxyl end not replaceable by DNA polymerase during DNA replication?
Loss of 30-200 nucleotides with each replication cycle
What is the repetitive non-coding sequence of DNA at the 3′ end, crucial for preventing loss of genetic information during replication?
5’-TTAGGG-3’
What is the structure called where telomeric DNA is packed into to hide the chromosome ends?
T-loop structure
What kind of proteins coat the telomeric DNA to protect it?
Shelterin proteins
This quiz covers the general concepts of DNA replication, processes in prokaryotic and eukaryotic cells, and different replication methods like conservative, semi-conservative, and dispersive. Test your knowledge on these topics!
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