DNA Replication - AP Biology
- What is the function of the sliding clamp in DNA replication?
- Increases processivity of DNA polymerase. Keeps polymerase attached for longer synthesis periods.
- What prevents the re-annealing of DNA strands during replication?
- Single-strand binding proteins. Coat separated strands to maintain single-strand state.
- What is the role of exonuclease in DNA replication?
- Removes mismatched nucleotides. Ensures accuracy by removing incorrectly paired bases.
- What is the role of telomerase in DNA replication?
- Extends telomeres in eukaryotic cells. Solves the end-replication problem at chromosome tips.
- What is the replication fork?
- Y-shaped region where new DNA strands are synthesized. Site of active DNA synthesis with exposed template strands.
- What is the function of primase in DNA replication?
- Synthesizes RNA primers. DNA polymerase requires a primer with a 3'-OH group to start.
- What is the primary enzyme responsible for synthesizing new DNA strands?
- DNA polymerase. This enzyme can add nucleotides to existing 3'-OH groups.
- Which protein complex aids in the loading of DNA polymerase?
- Clamp loader. Positions sliding clamp around DNA for processivity.
- Identify the strand synthesized discontinuously during DNA replication.
- Lagging strand. Synthesized away from the replication fork direction.
- Which enzyme catalyzes the formation of phosphodiester bonds in DNA?
- DNA ligase. Creates covalent bonds linking DNA backbone segments.
- Which nucleotide pairs with adenine during DNA replication?
- Thymine. Complementary base pairing follows Watson-Crick rules.
- Which enzyme removes RNA primers during DNA replication?
- DNA polymerase I. Has 5' to 3' exonuclease activity for primer removal.
- Identify the short sequences of RNA that initiate DNA synthesis.
- RNA primers. Provide the 3'-OH group needed for DNA polymerase initiation.
- What is the function of DNA ligase in DNA replication?
- Joins Okazaki fragments. Forms phosphodiester bonds between adjacent DNA segments.
- Identify the direction of the template strand for leading-strand synthesis.
- 3' to 5' direction. Template runs antiparallel to the synthesis direction.
- Identify the phase of the cell cycle in which DNA replication occurs.
- S phase. Synthesis phase when DNA content doubles in the cell.
- What are the short DNA fragments synthesized on the lagging strand called?
- Okazaki fragments. Result from discontinuous synthesis on the lagging strand.
- What is required for DNA polymerase to begin synthesis?
- RNA primer. DNA polymerase cannot initiate synthesis de novo.
- Which enzyme relieves the strain of unwinding DNA during replication?
- Topoisomerase. Prevents excessive supercoiling ahead of the replication fork.
- Identify the nucleotide that pairs with cytosine in DNA.
- Guanine. Forms three hydrogen bonds with cytosine in base pairs.
- What is the origin of replication?
- Specific sequence where replication begins. Recognized by initiator proteins to start replication.
- Which molecule provides the energy for DNA polymerization?
- Deoxyribonucleoside triphosphates (dNTPs). Release of pyrophosphate drives the polymerization reaction.
- Which strand is synthesized continuously during DNA replication?
- Leading strand. Synthesized continuously in the 5' to 3' direction.
- Which enzyme synthesizes the new strand by adding nucleotides?
- DNA polymerase. Main replicative enzyme that extends DNA chains.
- What characterizes the lagging strand synthesis?
- Occurs in short Okazaki fragments. Synthesis occurs in segments due to 5' to 3' directionality.
- Identify the enzyme that initiates the unwinding of DNA.
- Helicase. Motor protein that moves along DNA breaking base pairs.
- What ensures the fidelity of DNA replication?
- Proofreading by DNA polymerase. 3' to 5' exonuclease activity removes incorrect nucleotides.
- What is the role of helicase in DNA replication?
- Unwinds the DNA double helix. Breaks hydrogen bonds between complementary base pairs.
- What does semiconservative replication mean?
- Each new DNA molecule has one old and one new strand. One parental strand is conserved in each new molecule.
- Identify the function of single-strand binding proteins in replication.
- Stabilize unwound DNA strands. Prevent secondary structure formation in exposed DNA.
- What is the template strand in DNA replication?
- The original DNA strand used for synthesis. Provides the sequence information for new strand synthesis.
- Identify the enzyme that corrects supercoiling during replication.
- Topoisomerase. Relieves tension from unwinding by creating temporary breaks.
- Identify the direction in which DNA polymerase synthesizes new DNA.
- 5' to 3' direction. DNA polymerase can only add nucleotides to the 3' end.