Quiz 6

Replication Bubble

• DNA polymerase adds nucleotides in a continuous manner at the leading strand.

Origin of Replication

• Replication begins at a specific DNA sequence called the origin of replication.

Topoisomerase

• Topoisomerase relaxes the tension in the DNA double helix that builds up ahead of the replication fork by cutting and rejoining the DNA strands.

Polymerase Accuracy

• Polymerase maintains the accuracy of DNA replication by proofreading and editing its work, correcting any errors that occur during DNA synthesis.

DNA Strand Bonds

• The bonds that link two DNA strands together are hydrogen bonds.

Origin of Replication Characteristics

• The sequence at which DNA replication begins tends to have a characteristic of being rich in adenine (A) and thymine (T) bases.

Double-Strand Break Repair

• The simple ligation mechanism of double-strand break repair is non-homologous end joining (NHEJ).

Primers

• Primers from which DNA synthesis starts are different from the DNA itself in that they are short RNA molecules, typically 10-12 nucleotides in length, that provide a free 3' hydroxyl group for DNA synthesis to begin.

DNA Synthesis

• If a stretch of DNA on the parental strand of a replicating chromosome has the sequence 5′–AGCTCGATCGGCTA–3′, the sequence of the newly synthesized strand made from this stretch of template will be 3′–TCGAGCTAGCCAT–5′.

Energy for Polymerization

• The energy for the polymerization reaction in DNA synthesis is powered by the hydrolysis of high-energy phosphate bonds in nucleotide triphosphates (dNTPs).