In a DNA double helix an adenine of one strand always pairs with a(n) _____ of the complementary strand, and a guanine of one strand always pairs with a(n) _____ of the complementary strand.
thymine ... cytosine
After DNA replication is completed, _____.
each new DNA double helix consists of one old DNA strand and one new DNA strand
Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments?
DNA polymerase can assemble DNA only in the 5' to 3' direction
The synthesis of a new strand begins with the synthesis of a(n) _____.
RNA primer complementary to a preexisting DNA strand
After replication is complete, the new DNAs, called _________, are identical to each other.
During DNA replication, an open section of DNA, in which a DNA Polymerase can replicate DNA, is called a
____________ are the short sections of DNA that are synthesized on the lagging strand of the replicating DNA.
Which part of a deoxynucleoside triphosphate (dNTP) molecule provides the energy for DNA synthesis?
Which of the following enzymes is important for relieving the tension in a helix as it unwinds during DNA synthesis?
One cycle of replication will produce ___daughter DNA molecules, each with one parental strand and one newly synthesized strand.
Single-strand binding proteins
bind to the single strands of DNA, preventing them from re-forming hydrogen bonds with each other and allowing synthesis to occur in both strands.
DNA Polymerase III
synthesizes the new strands, but requires an existing 3 hydroxyl to add nucleotides
On the lagging strand, DNA ligase
joins Okazaki fragments by forming phosphodiester bonds between them, thus completing DNA replication.
daughter strand elongates toward replication fork, only one primer needed, and made continuously
made in segments, daughter strand elongates away from replication fork, multiple primers needed
Step one of lagging strand synthesis
A new fragment begins with DNA polymerase III binding to the 3' end of the most recently produced RNA primer, primer B in this case, which is closest to the replication fork. DNA pol III then adds DNA nucleotides in the 5' to 3' direction until it encounters the previous RNA primer, primer A.
Step two of lagging strand synthesis
DNA pol III falls off and is replaced by DNA pol I. Starting at the 5' end of primer A, DNA pol I removes each RNA nucleotide and replaces it with the corresponding DNA nucleotide. (DNA pol I adds the nucleotides to the 3' end of fragment B.) When it encounters the 5' end of fragment A, DNA pol I falls off, leaving a gap in the sugar-phosphate backbone between fragments A and B.