DNA replication
how a molecule of DNA is copied
transformation
a change in genotype and phenotype due to the assimilation of external DNA by a cell
bacteriophages or phages
bateria eaters
virus
DNA or sometimes RNA surronded by a protective coat
double helix
structural shape of DNA with the presence of two strands
antiparallel
subunits that run in opposite directions
semiconservitive model
predicts that when a double helix replicates each of the two daughter molecules will have one old strand, from the parental molecule, and one from the newly made strand
origins of replication
replication of a chromosome begins at particular sites
replication fork
a Y shaped region where the parental strands of DNA are being unwound
Helicases
are enzymes that untwist the double helix at the replication forks, seperating the parental strands and making them avaiable as template strands
single strand binding proteins
bind to the unpaired DNA strands keeping them from repairing
Topoisomerase
helps relieve this strain by breaking, swiviling and rejoining DNA strands
Primer
an RNA chain of nucleotoids that is produced during DNA synthasis
Primase
an enzyme that sythasizes primer
DNA polymerases
catalize the synthasis of ne DNA by adding nucleotoids to a preexisting chain.
leading strand
DNA strand made by DNA pol III remains in the replication fork on that template strands and continuously adds nucleoides to the new complimentory strand as the fork progresses
lagging strand
sythesized discontinuously as a series of segments
okazaki fragments
segments of the lagging strand
DNA ligase
enzyme joins the sugar backbone of all the okazaki fragments
mismatch repair
other enzymes remove and replace incorrectly paired nucleotides that have reslted from replication errors
nuclease
a DNA cutting enzyme cuts out a damaged portion of DNA strand
nucleotide excision repair
DNA repair system
telomeres
special nucleotide sequences a the end of eukaryotic chromosimal DNA molecules
chromotin
complex DNA and protein
heterochromatin
interphase chromatin visable as irregular clumps ith a light microscope
euchromatin
true chromatin