semiconservative replication
Replication in which the two nucleotide strands of DNA separate, each serving as a template for the synthesis of a new strand. All DNA replication is this type.
equilibrium density gradient centrifugation
Method used to separate molecules or organelles of different density by centrifugation.
replication origin
Sequence of nucleotides where replication is initiated.
replication fork
Point at which a double-stranded DNA molecule separates into two single strands that serve as templates for replication.
bidirectional replication
Replication at both ends of a replication bubble.
DNA polymerase
Enzyme that synthesizes DNA.
continuous replication
Replication of the leading strand in the same direction as that of unwinding, allowing new nucleotides to be added continuously to the 3? end of the new strand as the template is exposed.
leading strand
DNA strand that is replicated continuously.
discontinuous replication
Replication of the lagging strand in the direction opposite that of unwinding, which means that DNA must be synthesized in short stretches (Okazaki fragments).
lagging strand
DNA strand that is replicated discontinuously.
Okazaki fragment
Short stretch of newly synthesized DNA. Produced by discontinuous replication on the lagging strand, these fragments are eventually joined together.
initiator protein
Binds to an origin of replication and unwinds a short stretch of DNA, allowing helicase and other single-strand-binding proteins to bind and initiate replication.
DNA helicase
Enzyme that unwinds double-stranded DNA by breaking hydrogen bonds.
single-strand-binding (SSB) protein
Binds to single-stranded DNA in replication and prevents it from annealing with a complementary strand and forming secondary structures.
DNA gyrase
E. coli topoisomerase enzyme that relieves the torsional strain that builds up ahead of the replication fork.
primase
Enzyme that synthesizes a short stretch of RNA on a DNA template; functions in replication to provide a 3?-OH group for the attachment of a DNA nucleotide.
primer
Short stretch of RNA on a DNA template; provides a 3?-OH group for the attachment of a DNA nucleotide at the initiation of replication.
DNA ligase
Enzyme that catalyzes the formation of a phosphodiester bond between adjacent 3?-OH and 5?-phosphate groups in a DNA molecule.
proofreading
Ability of DNA polymerases to remove and replace incorrectly paired nucleotides in the course of replication.
mismatch repair
Process that corrects mismatched nucleotides in DNA after replication has been completed. Enzymes excise incorrectly paired nucleotides from the newly synthesized strand and use the original nucleotide strand as a template when replacing them.
telomerase
Enzyme that is made up of both protein and RNA and replicates the ends (telomeres) of eukaryotic chromosomes. The RNA part of the enzyme has a template that is complementary to repeated sequences in the telomere and pairs with them, providing a template f
homologous recombination
Exchange of genetic information between homologous DNA molecules.
Holliday junction
Model of homologous recombination that is initiated by single-strand breaks in a DNA molecule.
gene conversion
Process of nonreciprocal genetic exchange that can produce abnormal ratios of gametes following meiosis.
Every time we replicate our DNA loses DNA resulting in a 5' to 3' overhang therefore..
our telomeres get longer and longer.