Chapter 14 (DNA Structure and Function)

helicase

during replication, this enzyme helps to open up the DNA helix by breaking the hydrogen bonds

lagging strand

during replication, the strand that is replicated in short fragments and away from the replication fork

leading strand

strand that is synthesized continuously in the 5'-3' direction, which is synthesized in the direction of the replication fork

ligase

enzyme that catalyzes the formation of a phosphodiester linkage between the 3' OH and 5' phosphate ends of the DNA

mutation

variation in the nucleotide sequence of a genome

Okazaki Fragment

DNA fragment that is synthesized in short stretches on the lagging strand

point mutation

mutation that affects a single base

primase

enzyme that synthesizes the RNA primer; the primer is needed for DNA pol to start synthesis of a new DNA strand

primer

short stretch of nucleotides that is required to initiate replication; in the case of replication, the primer has RNA nucleotides

proofreading

function of DNA pol in which it reads the newly added base before adding the next one

replication fork

Y-shaped structure formed during initiation of replication

silent mutation

mutation that is not expressed

telomerase

enzyme that contains a catalytic part and an inbuilt RNA template; it functions to maintain telomeres at chromosome ends

transformation

process in which external DNA is taken up by a cell