ch 11 dna replication Flashcards
dna replication
the process in which original dna strands are used as templates for the synthesis of new dna strands
template strand
(also called parental strand) a strand of dna that is used to synthesize a complementary strand of dna or rna
daughter strands
in dna replication, the two newly made strands of dna
conservative model
an incorrect model of dna in which both parental strands of dna remain together following dna replication
semiconservative model
the correct model for dna replication which the newly made double-stranded dna contains one parental strand and one daughter strand
dispersive model
an incorrect model for dna replication in which segments of parental dna and newly made dna are interspersed in both strands following the replication process
origin of replication
a site on a chromosome that functions as an initiation site for the assembly of several proteins that begin the process of dna replication
bidirectional
- the manner in which two replication forks move, in opposite directions outward from the origin
- refers to a regulatory element that can function in either the forward or reverse direction
replication fork
the region in which two dna strands have separated and new strands are being synthesized
dnaA protein
a protein that binds to a dnaA box sequence at the origin of replication in bacteria and initiates replication
dnaA box
a dna sequence that serves as a recognition site for the binding of a dnaA protein
dna helicase
an enzyme that separates the two strands of dna
bidirectional replication
the phenomenon in which two dna replication forks emanate in opposite directions from an origin of replication
topoisomerase ii
(also called dna gyrase) an enzyme that introduces negative supercoils into dna using energy from atp and that can also relax positive supercoils when they occur
single-stranded binding protein
proteins that bind to both of the single strands of dna during dna replication and percent them from reforming a double helix
rna primer
a short strand of rna, made by primase, that is used to elongate a strand of dna during dna application
primase
an enzyme that synthesizes short rna primers during dna replication
leading strand
a strand during dna replication that is synthesized continuously toward the replication fork
lagging strand
a strand during dna replication that is synthesized as short okazaki fragments in the direction away from the replication fork
dna polymerase
an enzyme that catalyzes the covalent attachment of nucleotides to form a strand of dna
okazaki fragments
short segments of dna that are synthesized to produce the lagging strand during dna replication
dna ligase
an enzyme that catalyzes the formation of a covalent bond within the sugar-phosphate backbones of two dna strands
primosome
a protein complex that includes dna helicase and primase
replisome
a complex that contains a primosome and dimeric dna polymerase
dimeric dna polymerase
a complex of two dna polymerase holoenzymes that move as a unit during dna replication
termination (ter) sequences
in e. coli, a pair of sequences in the chromosome that bind a protein known as the termination utilization substance (Tus), which stops the movement of replication forks
catenanes
intertwined circular molecules
conditional mutant
a mutant whose phenotype depends on the environmental conditions, such as a temperature-sensitive mutant
temperature-sensitive (ts) mutant
a mutant that has a normal phenotype at a permissive temperature but a different phenotype, such as failure to grow, at a nonpermissive temperature
processive enzyme
an enzyme, such as rna or dna polymerase, which glides along the template strand and does not dissociate from it while catalyzing the covalent attachment of nucleotides
fidelity
a term used to describe the accuracy of a process; if there are few mistakes, a process has a high fidelity
proofreading function
the ability of dna polymerase to remove mismatched bases from a newly made strand
ars elements
dna sequences found in yeast that function as origins of replication
prereplication complex (preRC)
in eukaryotes, an assembly of at least 14 different proteins, including a group of proteins called the origin recognition complex (ORC), which acts as the first initiator of preRC assembly
origin recognition complex (ORC)
a group of proteins found in eukaryotes that acts as the first initiator of preRC assembly to begin dna replication
mcm helicase
a group of six proteins needed to complete a process called dna replication licensing, which is necessary for the formation of two replication forks at an origin of replication in eukaryotes
dna replication licensing
in eukaryotes, occurs when mcm helicase is bound at an origin of replication enabling the formation of two replication forks
polymerase switch
an exchange of one type of dna polymerase for another type during dna replication
translesion-replicating polymerase
a type of dna polymerase that can replicate over a dna region that contains an abnormal structure (ie a lesion)
flap endonuclease
an enzyme that removes small rna flaps that are generated by the action of dna polymerase δ; removes rna primers during dna replication
telomeres
specialized repeated sequences found at the ends of eukaryotic chromosomes
telomerase
the enzyme that recognizes telomeric sequences at the ends of eukaryotic chromosomes and synthesizes additional repeats of those telomeric sequences
telomerase rna component (TERC)
the rna component of telomerase
telomerase reverse transcriptase (TERT)
the enzyme within telomerase that uses rna as a template to make dna
senescent
describes a cell that is no longer capable of dividing
