21 Questions
What is the main purpose of DNA replication?
To pass genetic information from parent cell to daughter cells
When does DNA replication occur in the cell cycle?
During synthesis (S) phase
What is the term for the type of replication where each DNA strand acts as a template for the synthesis of a new complementary daughter strand?
Semiconservative replication
Which enzyme is primarily responsible for the synthesis of new DNA strands during replication?
DNA polymerase
Which enzyme synthesizes numerous RNA primers on the lagging strand during DNA replication?
Primase
What is the overall structure of a growing fork and steps in the synthesis of the lagging strand called?
Discontinuous replication
Which enzyme removes RNA primers and fills the gaps between Okazaki fragments with DNA during DNA replication?
DNA polymerase
What is the major role of topoisomerases during DNA replication?
Preventing DNA tangling
Which type of topoisomerase produces transient double-strand breaks in DNA?
Type II
What problem is caused when the last primer is removed at the extreme end of a chromosome during DNA replication?
End-replication problem
Which enzyme initiates DNA synthesis in eukaryotic replication by producing RNA-DNA oligonucleotides that prime synthesis of new DNA?
Primase
What happens to the chromosomal histone and nonhistone proteins during the S phase of DNA replication?
They are duplicated
When does replication begin for some replicons during S phase in eukaryotic cells?
Early in S phase
Which enzyme is responsible for unwinding the double-stranded DNA ahead of the replication fork?
Helicase
What type of replication includes repeated sequences in replication origins and many origins spaced at intervals in eukaryotic cells?
Eukaryotic replication
Which enzyme catalyzes the joining of nucleotides to form a growing DNA chain?
DNA Polymerase
What are the specific nucleotide sequences that initiate DNA replication called?
ORC
In which direction does DNA Polymerase synthesize DNA?
5' to 3'
What type of replication results in the synthesis of the lagging strand in small discontinuous fragments called Okazaki fragments?
Discontinuous replication
What is the term for the free nucleotides that serve as substrates in DNA replication?
dNTPs
Which enzyme is essential for initiating DNA synthesis by creating an RNA molecule?
Primase
Study Notes
- Coli by Körnberg: A groundbreaking discovery in molecular biology
- DNA polymerase: An enzyme that catalyzes the joining of nucleotides to form growing DNA chain
- Replication: Requires DNA polymerase and single-stranded DNA template
- dNTPs (dATP, dTTP, dGTP, dCTP): Free nucleotides serve as substrates in replication
- Origin of replication (ORC): Specific nucleotide sequences that initiate DNA replication
- Prokaryotes vs. eukaryotes: Differences in the number and distribution of replication origins
- Eukaryotic cells: Replication origins contain repeated sequences; many replication origins spaced at intervals
- DNA replication mechanism: Unwinding of dsDNA, formation of replication fork
- Helicase: Critical enzyme that unwinds double-stranded DNA ahead of the replication fork
- Replication fork: A Y-shaped structure composed of DNA helicase, SSBs, DNA polymerase, and primase
- DNA synthesis: Nucleotides added to 3' growing tips on each template, but in opposite directions
- DNA polymerase: Only synthesizes DNA in the 5' to 3' direction
- Primer: RNA molecule essential for initiating DNA synthesis
- Continuous vs. discontinuous replication: The leading strand is synthesized continuously, while the lagging strand is synthesized in small discontinuous fragments called Okazaki fragments.
Test your knowledge on DNA replication in medical biology. Learn and understand the process of DNA replication and its significance in passing genetic information from parent cell to daughter cells.
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