AP Biology 8th Edition Campbell and Reece
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| 84157466 | transformation | A change in genotype and phenotype due to the assimilation of external DNA by a cell. | |
| 84157467 | bacteriophage (aka phage) | A virus that infects bacteria. | |
| 84157468 | origin of replication | Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides. | |
| 84157469 | double helix | The form of native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape. | |
| 84157470 | semiconservative model | Type of DNA replication in which the replicated double helix consists of one old strand, derived from the old molecule, and one newly made strand. | |
| 84157471 | replication fork | A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are growing. | |
| 84157472 | helicase | An enzyme that untwists the double helix of DNA at the replication forks, separating the two strands and making them available as template strands. | |
| 84157473 | 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. | |
| 84157474 | 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. | |
| 84157475 | primase | An enzyme that joins RNA nucleotides to make the primer using the parental DNA strand as a template. | |
| 84157476 | primer | A short stretch of RNA with a free 3′ end, bound by complementary base pairing to the template strand, that is elongated with DNA nucleotides during DNA replication. | |
| 84157477 | 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 prokaryotes. | |
| 84157478 | leading strand | The new complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5′ → 3′ direction. | |
| 84157479 | 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. | |
| 84157480 | Okazi fragments | A short segment of DNA synthesized away from the replication fork on a template strand during DNA replication, many of which are joined together to make up the lagging strand of newly synthesized DNA. | |
| 84157481 | 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 a growing DNA chain). | |
| 84157482 | mismatch repair | The cellular process that uses specific enzymes to remove and replace incorrectly paired nucleotides. | |
| 84157483 | 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. | |
| 84157484 | nucleotide excision repair | A repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide. | |
| 84157485 | telomeres | The tandemly repetitive DNA at the end of a eukaryotic chromosome's DNA molecule that protects the organism's genes from being eroded during successive rounds of replication. See also repetitive DNA. | |
| 84157486 | telomerase | An enzyme that catalyzes the lengthening of telomeres in eukaryotic germ cells. | |
| 84157487 | nucleoid | A dense region of DNA in a prokaryotic cell. | |
| 84157488 | chromatin | The complex of DNA and proteins that makes up a eukaryotic chromosome. When the cell is not dividing, it exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope. | |
| 84157489 | heterochromatin | Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed. | |
| 84157490 | euchromatin | The less condensed form of eukaryotic chromatin that is available for transcription. |
