BIOL 2051 Lecture Notes - Lecture 8: Lac Operon, Sigma Factor, Pribnow Box
Document Summary
Transcription- making an rna copy of part of a dna strand. Dna- made of deoxyribonucleotides: double-stranded, thymine, sugar- deoxyribose. Rna- made of ribonucleotides: single-stranded, uracil, sugar- ribose. Three types of rna: mrna, contains information to make proteins, trna, carries amino acids to build the polypeptide during translation, rrna, component of ribosomes (site of protein synthesis) Template strand- dna strand that is being copied into complementary mrna. Rna polymerase- enzyme that transcribes dna into rna. Bacterial rna polymerase: 4 subunits: 2 copies of alpha ( ), beta ( ), beta ( ), sigma ( ) Transcription of rna from dna involves the enzyme rna polymerase, which adds ribonucleotides onto 3 end of growing rna chain. Unlike dna polymerase, rna polymerase needs no primer. Rna polymerase recognizes a specific start sequence on the dna called the promoter & starts transcribing dna into rna at that site. Sigma factor binds core rna polymerase: forms rna polymerase holoenzyme.
