CH 16 Flashcards
DNA replication
-copying of DNA
transformation
-a change in genotype and phenotype due to assimilation of foreign DNA
bacteriophages (phages)
-viruses that infect bacteria
virus
-DNA (sometimes RNA) enclosed by a protective coat, often simply protein
double helix
-DNA
-twisted ladder
antiparallel
-subunits run in opposite directions
semiconservative model
-predicts that when a double helix replicates, each daughter molecule will have one old strand (derived from parent molecule) and one newly made strand
origins of replication
-where the two DNA strands are separated
-short stretch of DNA that has a specific sequence of nucleotides
replication fork
-a Y-shaped region where new DNA strands are elongating
Helicases
-enzymes that untwist the double helix at the replication forks
Single-strand binding proteins
-bind to and stabilize single-stranded DNA
Topoisomerase
-relieves the strain of twisting of the double helix by breaking, swiveling, and rejoining DNA strands
primer
-RNA chain
-initial nucleotide strand
-free 3’ end
primase
-enzyme that joins RNA nucleotides to make a primer during DNA replication
DNA polymerases
-catalyze the synthesis of new DNA at a replication fork
leading strand
-moving toward the replication fork
lagging strand
-moving away from the replication fork
Okazaki fragments
segments synthesized by the lagging strand
DNA ligase
-linking enzyme essential for DNA replication
mismatch repair
-repair enzymes correct errors in base pairing
nucleotide excision repair
-a nuclease cuts out and replaces damaged stretches of DNA
nuclease
-DNA cutting enzyme
telomeres
-special nucleotide sequences at the ends of Eukaryotic chromosomal DNA molecules
chromatin
-complex of DNA and proteins
histones
-responsible for the first level of packing in chromatin
nucleosome
-basic unit of DNA packaging
euchromatin
-Loosely packed chromatin
heterochromatin
-highly condensed chromatin
