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DNA polymerase I

replaces RNA (primers) with DNA; has both polymerase and exonuclease (degrading of nucleotides) activity

DNA polymerase III

catalyzes elongation of new DNA at a replication fork by the addition of nucleotides to the existing chain; does the majority of synthesis


takes gaps/nicks in DNA (small holes with 5' and 3' ends) and fills them in (related to Okazaki fragments)


joins RNA nucleotides to make the primer using the parental DNA strand as a template


unwinds the two DNA strands for replication

single strand binding proteins

bind to the unwound & unpaired DNA strands, keeping them from re-pairing

DNA gyrase

works ahead of the replication fork; cuts DNA to relieve tension as unwinding is happening, and seals it back together


tandemly repetitive DNA at the end of eukaryotic DNA; protects coding region of the organism's DNA from being eroded during successive rounds of replication


an enzyme in eukaryotic cells that can add telomeres to the ends of chromosomes after they divide


messenger RNA: carries a copy of the protein-coding gene sequence (from DNA) to a ribosome


catalyzes peptize formation and provides the structural framework for ribosomes


carries amino acids to ribosomes for assembly into peptides

things necessary for transcription

1) DNA template; 2) ribonucleoside triphosphates (ATP, CTP, etc.); 3) RNA polymerase to catalyze reaction (1 in bacteria, 3 in eukaryotes)

RNA polymerase

enzyme that links together the growing chain of RNA nucleotides during transcription using a DNA strand as a template


(transcription) involves promoters, or short sequences to bind/orient RNA polymerase


(transcription) unwinding of DNA, reading of template strand 3'->5' and transcription 5'->3'


(transcription) ending of transcription signaled by specific base sequence; RNA polymerase falls or is pulled away


a specific sequence of three adjacent bases on a strand of DNA or RNA that provides genetic code information for a particular amino acid

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