[1] LEC: DNA Replication Flashcards
DNA replication occurs in which phase of the cell cycle?
S phase
The single strand binding protein is important in which stage of DNA replication?
initiation
This enzyme is important because it destroys and creates bonds ahead of the replication fork to relieve the torsion and stress caused by the replication bubble
topoisomerase
The extension of a strand of DNA after the addition of a primer is facilitated by ___
DNA polymerase III
Telomerase is important in which step of DNA replication?
Termination
If DNA polymerase I were mutated so that all its enzymatic activities were inactive, which part of replication would be most affected?
a. synthesis of okazaki fragments
b. joining of okazaki fragments
b
Okazaki fragments are used to elongate the ___ strand ___ (away or towards) the replication fork
lagging
away
T/F: During semiconservative replication, the original double helix template remains intact and a new double helix forms
F
T/F: the single stranded binding protein destroys the bonds between adenine and thymine to form the replication bubble
F
Since the first nucleotides cannot be linked in a newly synthesized strand in DNA replication, ___ is required
RNA primer
What would happen when the two replication forks meet each other and fuse?
Termination
Telomerases are responsible for the progressive synthesis of telomeric DNA repeats of ___
TTAGGG
___ join DNA fragments to the lagging strand
ligases
In the replication of DNA, the helix is opened and untwisted by ___
helicase
How many replication fork/s is/are there in a replication bubble?
2
Sites at which single-stranded DNA is exposed, and at which DNA synthesis occurs
replication fork
Direction of DNA replication
5’ to 3’
Specialized sites where DNA replication starts
Origin of replication
T/F: the origin of replication is where the DNA double helix is opened
T
In the initiation phase, the ___ breaks the bonds between the double helix structure
Pre-replication protein complex
This protein prevents the reannealing of the single stranded structure and prevents the DNA from being degraded by nucleases
Single stranded binding proteins
The enzyme that harnesses the chemical energy from the ATP hydrolysis to separate two DNA strands
helicase
The action of this enzyme usually causes tension and torsion
helicase
Fights positive supercoils by putting negative supercoils ahead of the replication fork, thus, the torsional strain is released
topoisomerase (II - gyrase)
Topoisomerase I are present in what type of organism/s?
eukaryotes
Topoisomerase II are present in what type of organism/s?
eukaryotes/prokaryotes
Topoisomerase IV are present in what type of organism/s?
prokaryotes
Examples of anticancer drugs made from topoisomerase I
Irinotecan, topotecan
Examples of anticancer drugs made from topoisomerase II
Etoposide, tenoposide, fluoroquinolones (ciprofloxacin, levofloxacin, moxifloxacin, ofloxcain, gemifloxacin, delafloxacin)
The elongation during replication is in what direction?
5’ to 3’
They are responsible for copying a short stretch of DNA template strand to produce RNA primer
primase
Hydrogen-bonded to template and provides a stable framework to which the nascent chain starts to grow
primase
The cut-and-patch process is also called the ___
nick translation
Seals the nick between the new strands in the lagging strans
ligase
Occurs when the two replication forks moving away from the single origin of replication meet on the opposite side of the circle
termination
when the forks approach each other, the replication complex disseminates and ___ occur
termination
