DNA transcription Flashcards
what are the 3 RNA molecules called
mRNA, tRNA and rRNA
what does mRNA do
encodes the amino acid sequence specified by a segment of DNA
what does tRNA do
transfers amino acids to a growing chain by encoding the mRNA sequence
what is rRNA
a constituent of ribosomes where protein synthesis occurs
what is transcription
enzyme system converts genetic information contained in a segment of the DNA double helix into a complimentary single strand of RNA
how many phases of transcription are there
3
what are the 3 phases of transcription called
initiation, elongation and termination
what happens during initiation
transcription does not require a primer so begins when the RNA polymerase binds to specific DNA sequences called promoters
describe promoters
they direct the transcription of adjacent segments of DNA
what do transcription factors do
regulate transcription
can upregulate or downregulate transcription by binding to sites on DNA allied to the promoter sequence or by altering activity of RNA polymerase
describe the assembly of the transcription machinery
DNA helicases- unwind the double helix of DNA
the topological strain on the DNA molecule is reduced by topoisomerases
how many types of RNA polymerase is there
3
what are the names of the 3 different RNA polymerases
RNA polymerase 1
RNA polymerase 11
RNA polymerases 111
what does RNA polymerase 1 do
synthesizes pre-ribosomal RNA which contains the precursors for 18S, 5.8S and 28S rRNAs
what does RNA polymerase 11 do
synthesizes mRNAs
