gene expression unit 6 AP Bio

• genome - DNA that exists in a living organism
• gene - instructions that code for traits, section of DNA
• exon - help build proteins
• intron - junk that's cut out
• helicase - splits/unzips DNA strand where hydrogen bonds are
• polymerase - glues/pastes new complementary nucleotides
• ligase - proofreads and rebonds hydrogen bonds between bases
• topoisomerase - prevents supercoils during the unzipping of DNA to be able to replicate DNA
• plasmids - circular and double stranded DNA molecules that are found in bacteria
• promoter region - TATA box
• anti-strand = not used
• coding strand - strand that is used and carries the information
• alternative splicing - same piece of DNA can become different proteins
• initiation - start of transcription, RNA polymerase binds to promoter and begins to unwind DNA
• elongation - addition of new amino acid to chain
• termination - RNA polymerase stops and is no longer transcribed
• operon - what a bacterial cell uses to build proteins
• lac operon - starts the building of lactose enzymes
• trp operon - repressive (prevents the binding of tryptophan when it's already present)
• parts of an operon

  p - promoter

  r - repressor

  o - operator

  g - genes
• transcription - the process of copying the DNA into mRNA, which is the first step in protein synthesis
• translation - the process of converting the information in a gene into a sequence of amino acids
• codon - a sequence of three nucleotides that codes for a specific amino acid
• primase - synthesizes short RNA primers
• repressor - a protein that binds to the operator and prevents transcription from occurring
• operator - DNA segment where the repressor binds to the operon model