Lecture 10 / Chapters 11 and 12 - DNA Replication and Packaging Flashcards
True or False?
The data obtained from the Meselson–Stahl experiment after one generation of replication eliminated the dispersive model of DNA replication.
False.
(The data obtained from the Meselson–Stahl experiment after one generation was consistent with both the semiconservative and the dispersive model of DNA replication. The conservative model of DNA replication was eliminated because it predicted that there would be two bands representing the original DNA at one density and the newly replicated DNA at a different density.)
Which enzyme catalyzes the addition of nucleotides to a growing DNA chain?
- Telomerase
- Helicase
- Primase
- DNA polymerase
DNA polymerase
DNA polymerase catalyzes the addition of nucleotides to a growing DNA chain.
Which of the following statements about DNA replication is true?
- DNA gyrase unwinds the DNA double helix.
- Okazaki fragments are DNA fragments synthesized on the leading strand.
- Single-stranded binding proteins stabilize the open conformation of the unwound DNA.
- DNA polymerase adds dNTP monomers in the 3’—5’ direction.
Single-stranded binding proteins stabilize the open conformation of the unwound DNA.
(Once helicase unwinds the double helix, single‑strand binding proteins bind to the open DNA and prevent it from winding together again.)
Which of the following terms accurately describes the replication of DNA in vivo?
- nonreciprocal
- nonlinear
- dispersive
- semidiscontinuous
- conservative
Semidiscontinuous
What is the function of helicase?
Helicase breaks the hydrogen bonds between the parental DNA strands and unwinds the double helix.
What is the function of the single-stranded binding proteins?
Single-stranded binding proteins bind to the single strands of DNA, preventing them from reannealing and allowing synthesis to occur on both strands.
What is the function of DNA polymerase III?
DNA polymerase III synthesizes the new strands, but it requires an existing 3′ hydroxyl (—OH) group to add nucleotides.
What is the function of primase?
Primase creates short RNA primers, initiating DNA synthesis on both template strands.
What is the function of DNA polymerase I?
DNA polymerase I removes the RNA primers and replaces them with DNA nucleotides.
What is the function of DNA ligase?
On the lagging strand, DNA ligase joins Okazaki fragments by forming phosphodiester bonds between them, thus completing DNA replication.
Which DNA polymerase is mainly responsible for genome replication in E. coli?
- DNA polymerase III
- DNA polymerase alpha
- DNA polymerase I
- DNA polymerase II
DNA polymerase III
DNA polymerase III is responsible for the synthesis of the bulk of the DNA in E. coli.
DNA polymerase III adds nucleotides ________.
- In the place of the primer RNA after it is removed
- to the 5’ end of the RNA primer
- to internal sites in the DNA template
- to the 3’ end of the RNA primer
- to both ends of the RNA primer
To the 3’ end of the RNA primer
Which activity of DNA polymerase I is responsible for proofreading the newly synthesized DNA?
- 5’ to 3’ polymerase
- 3’ to 5’ exonuclease
- 3’ to 5’ endonuclease
- 5’ to 3’ exonuclease
3’ to 5’ exonuclease
(If the wrong nucleotide is inserted, normal base pairing will not be observed and the base in error will be removed from the newly synthesized strand before subsequent nucleotides are added.)
DNA polymerase I is thought to add nucleotides ________.
- to the 3’ end of the primer
- In the place of the primer RNA after it is removed
- on single-stranded templates without need for an RNA primer
- to the 5’ end of the primer
- In a 5’ to 5’ direction
In the place of the primer RNA after it is removed
Which protein is responsible for the initial step in unwinding the DNA helix during replication of the bacterial chromosome?
DnaA
During DNA replication, an open section of DNA, in which a DNA polymerase can replicate DNA, is called a _____.
replication fork
The new DNA strand that grows continuously in the 5’ to 3’ direction is called the ______.
leading strand
