14: DNA Structure and Function Flashcards
technique used to separate DNA fragments according to size
electrophoresis
during replication, this enzyme helps to open up the DNA helix by breaking the hydrogen bonds
helicase
mutation that results from exposure to chemicals or environmental agents
induced mutation
during replication, the strand that is replicated in short fragments and away from the replication fork
lagging strand
strand that is synthesized continuously in the 5’-3’ direction, which is synthesized in the direction of the replication fork
leading strand
enzyme that catalyzes the formation of a phosphodiester linkage between the 3’ OH and 5’ phosphate ends of the DNA
ligase
type of repair mechanism in which mismatched bases are removed after replication
mismatch repair
variation in the nucleotide sequence of a genome
mutation
type of DNA repair mechanism in which the wrong base, along with a few nucleotides upstream or downstream, are removed
nucleotide excision repair
DNA fragment that is synthesized in short stretches on the lagging strand
Okazaki fragment
mutation that affects a single base
point mutation
enzyme that synthesizes the RNA primer; the primer is needed for DNA pol to start synthesis of a new DNA strand
primase
short stretch of nucleotides that is required to initiate replication; in the case of replication, the primer
primer
function of DNA pol in which it reads the newly added base before adding the next one
proofreading
Y-shaped structure formed during initiation of replication
replication fork
mutation that is not expressed
silent mutation
during replication, protein that binds to the single-stranded DNA; this helps in keeping the two strands of DNA apart so that they may serve as templates
single-strand binding protein
ring-shaped protein that holds the DNA pol on the DNA strand
sliding clamp
mutation that takes place in the cells as a result of chemical reactions taking place naturally without exposure to any external agent
spontaneous mutation
enzyme that contains a catalytic part and an inbuilt RNA template; it functions to maintain telomeres at chromosome ends
telomerase
DNA at the end of linear chromosomes
telomere
enzyme that causes underwinding or overwinding of DNA when DNA replication is taking place
topoisomerase
process in which external DNA is taken up by a cell
transformation
when a purine is replaced with a purine or a pyrimidine is replaced with another pyrimidine
transition substitution
when a purine is replaced by a pyrimidine or a pyrimidine is replaced by a purine
transversion substitution
