Bio Unit 2

downstream region

3’ end, where the gene transcription ends

upstream region

5’ end, where the gene transcription begins

promoter

DNA sequence that determines if/where the RNA will start, recruits RNA polymerase

TSS

transcription start site

template strand

DNA strand that is copied

coding strand

DNA strand that is not copied, same sequence as RNA strand

RNA polymerase

catalyzes transcription, substrates are free NTP and 3’ end of DNA

tRNA

transfer RNA, bring amino acids to the site of synthesis

mRNA

messenger RNA, translated into protein

rRNA

ribosomal RNA, functional in protein synthesis

nucleotide excision repair

DNA repair pathway, removal of large mutated sections

thymine dimer

DNA mutation caused by UV, causes DNA strand to kink

radiation damages to DNA

changes to sugar phosphate backbone, breaks in DNA

silent mutation

change of nucleotide that does not cause an amino acid change

missense mutation

change of nucleotide that makes 1 different amino acid

frameshift mutation

insertion of nucleotide that changes the following amino acids (usually deleterious*)

nonsense mutation

change of nucleotide that changes an amino acid to a stop codon (usually deleterious*)

mutation prevention methods

proofreading, mismatch repair, nucleotide excision repair

proofreading

3’ exonuclease activity of DNA polymerase 3, removes incorrect nucleotides and puts them in exonuclease region

mismatch repair

enzymes can recognize incorrect matching and cleave out incorrect nucleotides