II. Copying the Genetic Blueprint: DNA Replication Flashcards
(34 cards)
What is meant by the term semiconservative as it applies to DNA replication?
Semiconservative means that during DNA replication, each new DNA molecule consists of one parental strand and one newly synthesized daughter strand.
During the replication of DNA, what is the parental strand? What is the daughter strand? Which one serves as the template strand?
The parental strand is the original DNA strand, while the daughter strand is the newly synthesized strand. The parental strand serves as the template strand.
What is the precursor of each new nucleotide in a ‘growing’ DNA strand?
The precursor of each new nucleotide is a deoxynucleotide triphosphate (dNTP).
To which end (5’ or 3’) of the ‘growing’ DNA strand are new nucleotides added? Why can’t they be added to the other end?
New nucleotides are added to the 3’ end of the growing DNA strand because DNA polymerases can only add nucleotides in the 5’ to 3’ direction.
How many energy-rich phosphate bonds are consumed to add each new nucleotide?
Two energy-rich phosphate bonds are consumed to add each new nucleotide.
What are DNA polymerases?
DNA polymerases are enzymes that synthesize DNA molecules from deoxynucleotide triphosphates.
In E. coli, which DNA polymerase is primarily responsible for replicating the bacterial chromosome?
DNA polymerase III is primarily responsible for replicating the bacterial chromosome in E. coli.
In E. coli, what are the other DNA polymerases used for?
Other DNA polymerases in E. coli are used for processes such as DNA repair and replication of damaged DNA.
In which direction do DNA polymerases synthesize DNA?
DNA polymerases synthesize DNA in the 5’ to 3’ direction.
In which direction do DNA polymerases move down the template strand of DNA during DNA replication?
DNA polymerases move down the template strand in the 3’ to 5’ direction.
In the process of DNA replication, what are primers and why are they needed? What enzyme makes these primers?
Primers are short RNA sequences needed to initiate DNA synthesis. They are made by the enzyme primase.
Where does DNA replication begin on the bacterial chromosome?
DNA replication begins at the origin of replication on the bacterial chromosome.
What is the function of protein DnaA? What is the function of protein DnaC?
Protein DnaA binds to the origin of replication to initiate DNA replication, while protein DnaC helps load helicase onto the DNA.
What is the function of helicase?
Helicase unwinds the DNA double helix ahead of the replication fork.
In the process of DNA replication, what is the replication fork? How many replication forks form on the circular bacterial chromosome?
The replication fork is the area where the DNA is unwound and replicated. Two replication forks form on the circular bacterial chromosome.
What enzyme is first loaded onto the DNA molecule at each replication fork? What enzymes are then loaded on to the DNA molecule?
DNA helicase is first loaded onto the DNA molecule at each replication fork, followed by DNA polymerase III.
In the process of DNA replication, what is the leading strand and what is the lagging strand?
The leading strand is synthesized continuously in the direction of the replication fork, while the lagging strand is synthesized in short segments away from the fork.
How does the process of leading strand synthesis differ from the process of lagging strand synthesis?
Leading strand synthesis is continuous, while lagging strand synthesis is discontinuous and involves Okazaki fragments.
What is the function of the sliding clamp (DnaN protein) during the process of DNA replication?
The sliding clamp holds DNA polymerase in place on the DNA strand during replication.
How many sliding clamps and how many DNA polymerase III enzymes are located at each replication fork?
There are two sliding clamps and two DNA polymerase III enzymes located at each replication fork.
What two functions are performed by DNA polymerase I?
DNA polymerase I removes RNA primers and fills in the gaps with DNA.
What function is performed by DNA ligase?
DNA ligase joins Okazaki fragments together by forming phosphodiester bonds.
On circular Bacterial and Archaeal chromosomes, DNA replication occurs bidirectionally. What does this mean?
Bidirectional replication means that DNA replication occurs in two directions from the origin of replication.
What is a theta structure?
A theta structure is a shape formed during the replication of circular DNA, resembling the Greek letter theta (θ).
