Chapter 7- DNA Replication Flashcards
duplication of a DNA molecule
DNA replication
DNA replication is a semi conservative process meaning
meaning the two OG strands of DNA will separate and each act as template to be copied by new strand
New resulting double strand of DNA post replication composed of
1 OG (parental) DNA strand and 1 New (daughter) DNA strand
DNA replication starts at a distinct location in chromosome called the
replication origin
sequence of DNA that recruits enzymes necessary for DNA replication happens at the
replication origin
Replication of DNA starts at the replication origin and begins a __________ process.
Bidirectional replication process
Why is is important for DNA replication to be bidirectional?
It takes less time for replication as opposed to being unidirectional
exact point where DNA strands separate and where DNA synthesis occurs
replication fork
when DNA is split, it creates _______ due to progression of bidirectional replication
two forks
DNA typically splits where weaker bonds are formed, which would be between
Adenosine and Thymine that are double hydrogen bonded
loop generated by unwound DNA double helix that gets bigger as replication forks move further away from each other
replication bubbles
DNA replication ends WHEN?
replication forks meet at termination site and all DNA has been copied
enzyme that separates DNA parental strands into single, template strands
DNA helicase
enzyme that removes RNA primer and replaces it w/ DNA
DNA Polymerase 1
enzyme polymerization of nucleotides during DNA replication (mainly duplicates DNA)
DNA Polymerase 3
enzyme that synthesizes DNA/ carries out polymerization; multiple exists and are either used for replication or repair
DNA Polymerase
In DNA Polymerization, nucleotides are only added to the _____ end because _______
3prime end; it has energy, where as the 5prime end does not.
3prime end has energy because
Incoming nucleotides have 3 phosphate groups aka (deoxynucleoties triphosphates) = energy
enzymes that creates small run of RNA (aka a primer ) so DNA polymerase has a free 3prime end , bc it cannot start adding dNTPs by itself
DNA primase
enzyme that uses ATP to fuse backbones (sugar and phosphates) of daughter strand “the joining enzymes” (also fuses okazaki fragments)
DNA ligase
protein that prevents template/parental DNA from sticking back together; keeps two template strands separated
Single Stranded DNA binding
DNA replication processes in order of enzymes
Helicase (separates DNA @ replication origin)–>SSB (stabilize separated DNA)–>Primase–> DNA Replication starts (synthesis of daughter strand begins once is primer added) —> DNA pol3—-(adds dNtps to 3prime end of RNA primer)> DNA Pol1 (removes primers from daughter strands and replaces it with DNA)—> Ligase (fuses Okazaki fragments on daughter strands using ATP)
At replication fork, both daughter strands are synthesized simultaneously, these daughter strands are the
leading and lagging strands
DNA strand that is synthesized continuously (DNA pol3 adding dNtps to end of primer) in direction of replication fork is called ________
leading strand; the direction of synthesis is moving towards/ in same direction of the replication fork)
DNA strand that is synthesized discontinuously (DNA pol3 adding dNTPs to primer away from replication fork
lagging strand (the direction of synthesis is in the moving away from (going in opposite direction) of the replication fork)
DNA polymerase can only be synthesized in one direction, which is
5prime to 3prime
What does lagging strand require since it is synthesized discontinuously?
Another Primer added closer to replication fork
Once DNA Pol3 jumps to new primer and starts synthesizing another segment of daughter strand DNA on lagging strand, this results in
discontinuous pieces aka Okazaki fragments
