DNA Replication and Repair

Vocabulary flashcards for key terms related to DNA replication and repair.

Semiconservative Replication

Separating the two parent strands and building a new, complementary replacement strand for each.

Conservative Replication

Copying the DNA molecule “as is,” leaving the two original (parent) strands together.

Meselson and Stahl Experiment

An experiment that demonstrated that DNA replication is semiconservative using isotopes to label the parent DNA strands before replication.

Antiparallel

The two strands of DNA run in opposite directions to each other.

Replication Origins

Specific nucleotide sequences on the genome that act as starting points for DNA replication.

Helicase

An enzyme that binds to replication origins and begins to unwind the two strands of DNA by breaking the hydrogen bonds between the base pairs.

Replication Fork

A Y-shaped structure formed as the two DNA strands separate during replication.

Single-Strand Binding Proteins (SSB)

Proteins that prevent parent DNA strands from rejoining to each other once they have been separated.

Replication Bubble

The space between two replication forks that is filled with newly replicated DNA.

DNA Polymerases

Enzymes that join new nucleotides during replication and add nucleotides to the 3’ end of a new developing strand while moving along and “reading” the template strand in its 3’ to 5’ direction.

RNA Primase

Enzymes that begin the replication process by building a small complementary RNA segment on the strand at the beginning of the replication fork.

RNA Primers

Short, 10 to 60 pieces of RNA that are complementary to the template strand and act as starting points for DNA polymerase.

Leading Strand

The strand that is built continuously toward the replication fork and does not need additional primers.

Lagging Strand

The strand that is built away from the opening replication fork in a discontinuous manner.

Okazaki Fragments

Short DNA fragments, along with RNA primers, that make up the lagging strand.

DNA Polymerase I

An enzyme that removes RNA nucleotides one at a time and replaces them with DNA nucleotides.

DNA Ligase

An enzyme that catalyzes the formation of a phosphodiester bond, linking the last nucleotide to the Okazaki fragment in front of it.