DNA Replication Flashcards
DNA is an information storage unit. Information is copied during ______ and distributed during _______.
- interphase
- cell division
Replication characteristics
1. chemically unidirectional 5'->3' 2. spatially bidirectional (2 forks at once) 3. semi-conservative 4. semi-discontinuous
________ is the region of DNA that first separates and replication begins.
- origin of replication
In ______ DNA replication proceeds in both directions away from the origin of replication.
- bi directional replication
______ is the point of separation of double-stranded DNA at which incorporation of nucleotides occurs during DNA replication.
- replication fork
______ is where each separated polynucleotide strand serves as a template for the synthesis of a single new complementary strand.
- semi conservative replication
________ is the synthesis of DNA fragments that occurs in the lagging strand during DNA replication .
- semi discontinuous replication
_____ are the name given to discontinuous fragments of DNA synthesized in the lagging strand
- Okazaki fragments
Steps of DNA replication
- unwinding
- Primer synthesis (primase- RNA template)
- DNA synthesis (DNA polymerase 3).
- Replace RNA primers with DNA. (polymerase 1)
- Seal the gaps between the Okazaki fragments on lagging strand (ligase)
- Termination of synthesis (“ter” protein, telomeres).
In the _______ step of DNA synthesis DNA unwinds and stabilizes the duplex DNA to form the replication fork.
- initiation
_____ catalyzes the ATP-dependent unwinding of duplex DNA
- helicase
________ prevent supercoiling & tangling of DNA during unwinding; bind ahead of the replication fork, nick supercoiling DNA, relaxes stress by allowing uncoiling.
- topoisomerases
________ prevents re-annealing of the separated single strands and protects against nuclease degradation.
- ssDNA binding proteins
_____ is an RNA Polymerase that synthesizes a short RNA “primer”.
- primase
_______ cannot initiate DNA synthesis, they can only add nucleotides to the end of a chain that is base-paired with the template strand.
- DNA polymerases
_______ can initiate synthesis without primer.
- RNA polymerases
_______ extends the RNA-primed chain.
- DNA polymerase III
________ later replaces RNA with DNA.
- DNA polymerase I
_______ joins DNA (Okazaki) fragments.
- DNA ligase
A ______ is a series of repeated TTAGGG DNA sequences located at the ends of linear eukaryotic chromosomes
- telomere
Each time a cell divides/replication occurs, some of the _____ is lost due to exonuclease activity, degradation continues and the cell dies
- telomere
________ is an enzyme that restores (synthesizes) telomere sequence.
- telomerase
Termination of DNA replication involves ______ or, the sequences at the ends of chromosomes that buffer against the loss of critical coding sequences following a round of DNA replication
- telomeres
In eukaryotes, DNA ______ runs off the ends of DNA; replication bubbles fuse as polymerases “collide”
- polymerase
Termination of DNA replication in prokaryotes is due to ___ sequences and binding proteins
- Ter
Termination of DNA replication in eukaryotes is due to ___ and ____
- telomeres and telomerases
Initiation Factors, _______ proteins bind to origin of replication.
- DnaA proteins
_______ is the frequency with which an enzyme dissociates from the template during DNA replication.
- Processivity
The _______ t is a sliding clamp that helps to keep the DNA polymerase bound to the template during many rounds of nucleotide addition
- β subunit
