Chapter 13 Vocab

Antiparallel

Referring to the arrangement of the sugar-phosphate backbones in a DNA double helix (they run in opposite 5’→3’ directions)

Bacteriophage

A virus that infect bacteria; also called a phage

Chromatin

A complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is no dividing, ________ exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope.

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)\`

DNA Polyerase

An enzyme that catalyzes the elongation of the new DNA (for example, at a replication fork) by the addition of nucleotides t the 3’ end of an existing chain. There are several different _____ __________; _______ __III and__ ________ I play a major roles in DNA replication in E.coli

DNA Replication

The process by which a DNA molecule is copied; also called DNA synthesis

Double helix

The form os native DNA, referring to its two adjacent antiparallel polynucleotide strands wound around an imaginary axis into a spiral shape.

Helicase

An enzyme that untwists the double helix of DNA at replication forks, separating the two strands and making them available as template strands

Lagging Strand

A discontinuously synthesized DNA strand that elongates by means of Okazaki fragments, each synthesized in 5’→3’ direction away from the replication fork

Leading strand

The New complementary DNA strand synthesized continuously along the template strand toward the replication fork in the mandatory 5’→3’ direction

Mismatch repair

The cellular process that uses specific enzymes to remove and replace incorrectly pared nucleotide

Nuclease

An enzyme that cuts DNA or RNA, either removing one or a fe bases or hydrolyzing the DNA or RNA completely into its component nucleotides

Nucleoid

A non-membrane enclosed region in a prokaryotic cell where its chromosome is located

Nucleotide excision repair

A repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide

Okazaki fragment

A short segment 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.

Origin of Replication

Site where the replication of a DNA molecule begins, consisting of a specific sequence of nucleotides.

Phage

A virus that infects bacteria; also called a bacteriophage

Primase

An enzyme that joins RNA nucleotides to make a primer during DNA replication, using the parental DNA strand as a template.

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

Replication Fork

A Y-shaped region on a replicating DNA molecule where the parental strands are being unwound and new strands are being synthesized

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.

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

Telomerase

An __enzyme__ that adds __nucleotides__ to __telomeres__, especially in cancer cells.

Telomere

The tandemly repetitive DNA at the end f a eukaryotic chromosomeś DNA molecule. _______ protect the organismś genes from being eroded during successive rounds of replication

Topoisomerase

A protein that breaks, swivels, and rejoins DNA strands. During DNA replication, _________________ helps to relieve strain in the double helix ahead of the replication fork.

Transformation

(1) The process by which a cell in culture acquires the ability to divide indefinitely, similar to the division of cancer cells. (2)A change in genotype and phenotype due to the assimilation of external DNA by a cell. When the external DNA si from a member of a different species, _________ results in horizontal gene transfer.

Virus

An infectious particle incapable of eplicating outside of a cll, consisting of an RNA or DNA genome surrounded by a protein coat (capsid) and, for some viruses, a membranous envelope.