Key Terms
- electrophoresis
- technique used to separate DNA fragments according to size
- helicase
- during replication, this enzyme helps to open up the DNA helix by breaking the hydrogen bonds
- induced mutation
- mutation that results from exposure to chemicals or environmental agents
- 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
- mismatch repair
- type of repair mechanism in which mismatched bases are removed after replication
- mutation
- variation in the nucleotide sequence of a genome
- nucleotide excision repair
- type of DNA repair mechanism in which the wrong base, along with a few nucleotides upstream or downstream, are removed
- 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
- single-strand binding protein
- 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
- sliding clamp
- ring-shaped protein that holds the DNA pol on the DNA strand
- spontaneous mutation
- mutation that takes place in the cells as a result of chemical reactions taking place naturally without exposure to any external agent
- telomerase
- enzyme that contains a catalytic part and an inbuilt RNA template; it functions to maintain telomeres at chromosome ends
- telomere
- DNA at the end of linear chromosomes
- topoisomerase
- enzyme that prevents overwinding of DNA when DNA replication is taking place
- transformation
- process in which external DNA is taken up by a cell
- transition substitution
- when a purine is replaced with a purine or a pyrimidine is replaced with another pyrimidine
- transversion substitution
- when a purine is replaced by a pyrimidine or a pyrimidine is replaced by a purine
