Chapter 16 - Molecular Basis of Inheritance Flashcards
The process by which a DNA molecule is copied; also called DNA synthesis
DNA replication
A change in genotype and phenotype due to the assimilation of external DNA by a cell
Transformation
An infectious particle incapable of replicating outside of a cell, consisting of an RNA or DNA genome surrounded by a protein coat (capsid); some also have a membranous envelope
Virus
The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape
Double Helix
Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5’ –> 3’ directions).
Antiparallel
Type of DNA replication in which the replicated double helix consists of one old strand derived from the parental model and one newly made strand
Semiconservative model
Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides
Origins of replication
A y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized
Replication Fork
Enzymes that untwist the double helix of DNA at replication forks, separating the two strands and making them available as template strands
Helicases
A protein that binds unpaired DNA stands during DNA replication, stabilizing them and holding them apart while they serve as templates for the synthesis of complementary strands of DNA
Single-Strand Binding Proteins (SSB Proteins)
A protein that breaks, swivels, and rejoins DNA stands. During DNA replication, it helps relieve strain in the double helix ahead of the replication fork.
Topoisomerase
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
Primer
Enzyme that joins RNA nucleotides to make a primer during RNA replication, using the parental DNA strand as a template
Primase
Enzyme that catalyzes the elongation of new DNA (for example, the replication fork) by the addition of nucleotides to the 3’ end of an existing chain. There are several different types of this enzyme - #1 and 3 play major roles in DNA replication in E. Coli.
DNA Polymerase
The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5’ –> 3’ direction
Leading 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
Lagging strand
A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication. Many such segments are joined together to make up the lagging strand of newly synthesized DNA.
Okazaki Fragments
A linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3’ end of one DNA fragment (such as an Okazaki fragment)
DNA ligase
Cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides
Mismatch repair
An enzyme that cuts DNA or RNA either by removing one or a few bases or hydrolyzing the DNA or RNA completely into its component nucleotides
Nuclease
A repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide
Nucleotide Excision Repair
Tandemly repetitive DNA at the end of a eukaryotic chromosome’s DNA molecule. These protect the organism’s genes from being eroded during successive rounds of replication.
Telomere
Enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells
Telomerase
Complex of DNA and proteins that makes up eukaryotic chromosomes. When a cell is not dividing, this exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.
Chromatin
Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed
Heterochromatin
Less condensed form of eukaryotic chromatin that is available for transcription
Euchromatin
