Chapter 6: DNA Replication Flashcards
because replication is (), each strand of the parental double helix acts as a template for the synthesis of a new daughter DNA strand
semi-conservative
3 phases of DNA synthesis
- initiation
- elongation
- termination
replication starts at special sites called ()
origins of replication
replication moves away from the origin in (1), forming a (2)
- both directions
- replication bubble
the DNA double helix is opened at the origin of replication and unwound to form ()
replication forks
at replication forks, () is exposed and DNA synthesis can occur
single-stranded DNA (ssDNA)
for bacteria, the origin of replication is typically a single site called ()
ori
in most eukaryotes, the origins of replication are () along the chromosome
multiple, not sequence-specific
the origin of replication is recognized by an () that opens up the double helix and recruits helicases
initiator protein
() unwind the double helix to expose ssDNA
DNA helicases
ssDNA is coated with () to prevent it from forming secondary structures or re-pairing, and to protect it from endonucleases
ssDNA binding proteins
DNA synthesis is carried out by (), but it can only add nucleotides to an existing 3’ end
DNA polymerase (III)
because DNA polymerase cannot synthesize new strands de novo, DNA synthesis needs a (1) synthesized by an RNA polymerase called (2)
- primer
- primase
DNA polymerase us recruited by the (1) to the DNA at the (2)
- sliding clamp
- primer 3’ terminus
after the RNA primer is synthesized, the (1) loads the (2) onto the DNA template strand
- clamp loader
- sliding clamp
in eukaryotes, the first few nucleotides are synthesized by (1), which forms (2)
- DNA polymerase alpha
- polymerase alpha - primase complex
DNA synthesis on both template strands occurs in a () direction
5’ to 3’
due to the 5’ to 3’ direction of DNA synthesis, synthesis is continuous on the (1), but discontinuous on the (2)
- leading strand
- lagging strand
polymerases, helicases, and primases are organized into the () at the replication fork
replisome
(dimeric) polymerases on both leading and lagging strands travel () at the replication fork
together behind the helicases
termination of DNA synthesis occurs when:
- 2 different forks meet
- the fork reaches the end of a linear chromosome
- polymerase meets the previously replicated strand
because RNA primers were used to start DNA synthesis, they must be () during termination
removed and replaced with DNA
in the case of discontinuous synthesis or replacement of RNA primers, () connects the adjacent strands
DNA ligase
bacterial DNA synthesis termination occurs at a specific region called ()
ter