Chapter 16 - The Molecular Basis of Inheritance Flashcards
DNA replication
The process by which a DNA molecule is copied; also called DNA synthesis.
transformation
(1) The conversion of a normal animal [or human] cell to a cancerous cell. (2) A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA is from a member of a different species, transformation results in horizontal gene transfer.
bacteriophage
A virus that infects bacteria; also called a phage.
virus
An infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope.
double helix
The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.
antiparallel
Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5’ → 3’ directions).
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.
helicase
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 templates for the synthesis of complementary strands of DNA.
topoisomerase
A protein that breaks, swivels, and rejoins DNA strands. During DNA replication, topoisomerase helps to relieve strain in the double helix ahead of the replication fork.
primer
A short stretch of RNA 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
An enzyme that catalyzes the elongation of new DNA (for example, at a replication fork) by the addition of nucleotides to the 3’ end of an existing chain. There are several different DNA polymerases; DNA polymerase III and DNA polymerase I play major roles in DNA replication in <em>E. coli</em>.
leading strand
The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5’ → 3’ direction.
lagging strand
A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in a 5’ → 3’ direction away from the replication fork.
Okazaki fragment
A short segment of DNA synthesized away form the replication fork
DNA ligase
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3’ end of one DNA fragment (such as an Okazaki fragment) to the 5’ end of another DNA fragment (such as 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. Telomeres protect the organism’s genes from being eroded during successive rounds of replication. <em>See also</em>
telomerase
An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells.
