24 Questions
What is the composition of each daughter DNA molecule?
One old strand and one new strand
What is the base pairing rule in DNA replication?
Adenine pairs only with Thymine
What is the direction of the complementary strand in DNA replication?
Opposite direction of the template strand
What is the function of DNA polymerase in DNA replication?
Synthesis of new DNA strands
What is the role of DNA ligase in DNA replication?
Joining Okazaki fragments
What is the direction of DNA synthesis?
5' to 3' direction
What is the function of topoisomerase in DNA replication?
Relieving torsional strain
What is the requirement for DNA synthesis?
Both a template and a primer
What is the direction of DNA synthesis in the leading strand?
5´- 3´ direction
What is the function of the primase enzyme?
To synthesize a short stretch of RNA complementary to the template DNA strands
What is the role of DNA polymerase ε in replication?
To synthesize the leading strand
What is the function of ligase enzyme in replication?
To connect Okazaki fragments into one continuous strand
What is the direction of DNA synthesis in the lagging strand?
Direction away from the replication fork
What are Okazaki fragments?
Small DNA segments synthesized in a discontinuous manner
What is the direction of the replication fork movement?
Towards Ori
What is the direction of DNA polymerase δ synthesis in the lagging strand?
In the opposite direction of the advancing replication fork
What is the primary function of helicase enzymes in DNA replication?
To break the hydrogen bonds between DNA strands
What is the purpose of topoisomerase enzymes in DNA replication?
To solve the problem of supercoiling
What is the characteristic of the short sequence at the origin of replication?
Composed only of AT base pairs
What is the role of single-stranded binding proteins in DNA replication?
To keep the two strands of DNA apart
What is the shape of the structure formed during DNA replication?
V-shaped
What is the problem that occurs in the region of DNA ahead of the replication fork?
Supercoiling
What is the function of the primer in DNA replication?
To initiate DNA synthesis
What is the direction of DNA synthesis in semi-conservative replication?
5´-3´
Study Notes
Structure of DNA
- Each daughter DNA molecule consists of one old strand (parental strand) and one new strand (from free nucleotides in the nucleus)
- The base pairing rule is maintained: Adenine pairs with Thymine (A-T, two H bonds) and Cytosine pairs with Guanine (C-G, three H bonds)
- A + G = T + C in DNA molecule
Replication Process
- Replication is a bidirectional process that proceeds in both directions
- Synthesis of new strand occurs in 5' to 3' direction by DNA polymerase
- The process requires a template, primer, and substrates (dATP, dGTP, dCTP, and dTTP)
Enzymes and Proteins Involved
- DNA helicases: unwind double-stranded DNA
- Single-stranded DNA binding protein (ssDB): stabilizes single-stranded DNA
- Primase: synthesizes RNA primer
- DNA polymerase: chief enzyme for DNA chain elongation, repair, and proofreading
- DNA ligase: joins Okazaki fragments
- Topoisomerase: relieves torsional strain by cutting and joining single strands or both strands
Steps of DNA Replication
- Identification of the origin of replication
- Unwinding of double-stranded DNA by DNA helicase
- Binding of single-stranded DNA by ssDB
- Synthesis of RNA primer by primase
- Synthesis of new DNA strand by DNA polymerase
- Proofreading and repair by DNA polymerase
- Ligation of newly synthesized DNA segments by DNA ligase
Leading Strand and Lagging Strand
- Leading strand: synthesized continuously in 5' to 3' direction by DNA polymerase ε
- Lagging strand: synthesized discontinuously in short fragments (Okazaki fragments) by DNA polymerase δ
Primers Removal and Ligation
- Excision of RNA primers by exonucleases
- Removal of RNA primers and ligation of newly synthesized DNA segments by DNA ligase
This quiz covers the process of DNA replication, including the conservation of one parent strand, the formation of a new strand, and the importance of base pairing rules. It also touches on the anti-parallel structure of DNA strands.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
