Chapter 16 Flashcards
(25 cards)
transformation
the process by which a cell in culture acquires the ability to divide indefinitely, similar to the division of cancer cells
bacteriophage
a virus that infects bacteria; also called phage
virus
an infectious particle incapable of replicating outside a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid), and some by a membranous envelope
antiparallel
referring to the arrangement of the sugar-phosphate backbone in a DNA double helix (run in opposite 5’ to 3’ directions)
DNA replication
DNA molecule is copied
semiconservative model
type of DNA replication in which the replicated double helix consists of one old strand, derived from the parental molecule, and one newly made strand
origin of replication
site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides
replication fork
a y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized
helices
an enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands
single-strand binding protein
a protein that binds to the unpaired DNA strands during DNA replication, stabilizing them and holding them apart while they serve as template for the synthesis of complementary strands of DNA
topoisomerase
a protein that breaks, swivels, and rejoins DNA strands, helps relieve strain in the double helix ahead of the replication fork during DNA replication
primer
a short polynucleotide with a free 3’ end, bound by complementary base pairing to the template strand and elongated with DNA nucleotides during DNA replication
primase
an enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parental DNA strand as a template
DNA polymerase
enzyme that catalyzes the elongation of new DNA (eg. at a replication fork) by the addition of nucleotides to the 3’ end of an existing chain
leading strand
the new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the 5’ to 3’ direction
lagging strand
a discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in the 5’ to 3’ direction away from the replication fork
Okazaki fragments
a short segment of DNA synthesized away from the replication fork on a template strand during DNA replication; many segments are joined together to make up the lagging strand of newly synthesized DNA
DNA ligase
a linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3’ end of one DNA fragment (eg. an Okazaki fragment) to the 5’ end of another DNA fragment (eg. a growing DNA chain)
mismatch repair
the cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides
nuclease
an enzyme that cuts DNA or RNA, either removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides
nucleotide excision repair
a repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide
telomere
the tandemly repetitive DNA at the end of a eukaryotic chromosome’s DNA molecule; protect the organism’s genes from being eroded during successive rounds of replication
chromatin
complex of DNA and proteins that makes up eukaryotic chromosomes; when the cell is not dividing, exists in its dispersed form, as a mass of very long, thin fibers
euchromatin
the less condensed form of eukaryotic chromatin that is available for transcription
