Vocabulary for Unit 8 Flashcards
Origin of repication
The site on the chromosome at which DNA replication begins.
Initiator protein
Proteins that catalyze the unwinding of duplex DNA during replication by binding cooperatively to single-stranded regions of DNA or to short regions of duplex DNA that are undergoing transient opening.
Topoisomerase
An enzyme that cuts and rejoins DNA downstream of the replication fork, to ease the twisting that would otherwise occur as the DNA “unzips”.
Primase
An enzyme that synthesizes a short stretch of RNA to use as a primer during DNA replication.
Single-stranded DNA binding protein
binds to single-stranded regions of DNA to prevent premature annealing, to protect the single-stranded DNA from being digested by nucleases, and to remove secondary structure from the DNA to allow other enzymes to function effectively upon it.
Helicase
An enzyme that catalyzes the breaking of hydrogen bonds between nucleotides of DNA, “unzipping” a double stranded DNA molecule.
DNA polymerase
Any enzyme that catalyzes synthesis of DNA from deoxyribonucleotides.
5’ to 3’ polymerase
?
3’ to 5’ editing function
?
5’ to 3’ exonuclease
?
Clamp protein
?
Ligase
An enzyme that brings about the joining of two DNA strands or other molecules by a phosphate ester linkage.
Initiation
(1) In an enzyme-catalyzed reation, the stage during which enzymes orient reactants precisely as they bind at specific locations within the enzyme’s active site.
(2) In DNA transcription, the stage during which RNA polymerase and other proteins assemble at the promoter sequence.
(3) In RNA translation, the stage during which a complex consisting of a ribosome, a mRNA molecule, and an animoacyl tRNA corresponding to the start of a codon is formed.
