Lesson 2- Transcription Flashcards
function of promoter region
RNA polymerase binds to the DNA and unwinds near the beginning 5’ end of a gene at the promoter (nucleotide sequence) for transcription intitation
similarities of DNA polymerase and RNA polymerase
DNA repliactes chromosomes by adding one nucleotide to the 3’ end of strand
RNA transcribes mRNA by adding one nucleotide to the 3’ end of RNA strand
coding strand
DNA strand not being copied but contains the same sequence as the new RNA molecule (no uracial, add thymine)
template strand
DNA 3’ to 5’ being copied by RNA polymerase
stage 1- initation
RNA polymerase binds to DNA and begins to unwind at the beginning at the promoter which has a TATA box that enables binding, has high percentage of thymine and adenine for polymerase to recongnize because they only have two bonds which take less energy to break
stage 2- elongation
polymerase starts to build the RNA molecule without a primer and uses 3’ to 5’ end of DNA as a template strand. the other strand is the coding strand but the template strand is complementary to the sequence that is transcribed. nucleotides are added and the RNA is elongated and unwinds for DNA double-helix
stage 3- termination
polymerase recognizes a termination sequence (bases), eukaryote sequence is adenines transcribe to uracils on RNA and nuclear proteins bind to it to stop. the synthesized RNA dissociates from template strand
primary transcript molecule
pre-mrna is the newly transcribed eukaryotic rna, it has to undergo modifications before it exits the nucleus because it is vulnerable to the enzymes and conditions outside
poly-A-tail
sequence of adenine-nucleotides added to 3’ cap end of the pre-mrna molecule to protect the strand from RNA-digesting enzymes in the cytosol
5’ cap
a sequence of seven-G’s added to the start of pre-mrna stand for ribosomes to recognize and attach to this site for translation
removal of introns
introns are a non-coding sequence of DNA or RNA but need to be removed because they would alter/add to the amino acid sequence adn the protein would not fold or function properly
exon
sequence of DNA or RNA that codes for part of a gene
differences between transcription in eukaryotes and prokaryotes
eukaryotes (prokaryotes)- takes place in nucleus (throughout the cell, dif. RNA polymerases are used (single polymerase), bases added slowly (quickly), promoters are more complex (less complex), nuclear proteins bind to polyuracil site and terminate (mrna binds with itself or protein binds to mrna), there are intons and exons (no introns), results in pre-mrna which is modified (results in mrna)
