Lecture 15 Flashcards
(12 cards)
DNA ligase
A linking enzyme essential for Dna replication; catalyzes the covalent bonding of the 3’ end of one dna fragment to the 5’ end of another DNA fragment.
DNA polymerase
An enzyme
that catalyzes the elongation of new
DNA (for example, at a replication fork) by
the addition of nucleotides to the 3? end of
an existing chain. There are several different
DNA polymerases; DNA polymerase III and
DNA polymerase I play major roles in DNA
replication in E. coli.
helicase
An enzyme that untwists the double
helix of DNA at replication forks, separating
the two strands and making them available
as template strands.
lagging strand
A discontinuously synthesized
DNA strand that elongates by means
of Okazaki fragments, each synthesized in a
5?S 3? direction away from the replication
fork.
leading strand
The new complementary
DNA strand synthesized continuously along
the template strand toward the replication
fork in the mandatory 5?S 3? direction.
mismatch repair
The cellular process that
uses specific enzymes to remove and replace
incorrectly paired nucleotides.
nuclease
An enzyme that cuts DNA or RNA,
either removing one or a few bases or hydrolyzing
the DNA or RNA completely into
its component nucleotides.
origin of replication
Site where the replication
of a DNA molecule begins, consisting
of a specific sequence of nucleotides.
primase
An enzyme that joins RNA nucleotides
to make a primer during DNA replication,
using the parental DNA strand as a
template.
primer
A short stretch of RNA with a free 3?
end, bound by complementary base pairing
to the template strand and elongated with
DNA nucleotides during DNA replication.
replication fork
the “fork in the road” of DNA replication
telomere
The ends of eukaryotic chromosomal DNA molecules, the telomeres, have special nucleotide sequences
