Gene expression Flashcards
what initiates transcription
when the rna polymerase and transcription factors assemble at the promoter region
what happens in transcription
rna polymerase runs along the template strand in a 3-5 directly, unwinding and unzipping the dna and building a complementary strand of pre mrna in a 5-3 direction
where does the pre mrna originally come from
free floating rna nucleotides in the nucleuus , these unpaired bases are placed/ temporarily binds to the template strand based on complementary base rules
what happens and when does transcription stop
when a temination sequence in reached, not copied and then the bonds between the complementary and coding strand reformed into dna
pre mrna is aka
primary transcript
what happens during rna processing
methyl cap is added to 5’ end, poly a tail is added to 3’ end, introns cut out, exons spliced together
what are the three steps of converting a gene to a protein
transcription, rna processing, translation
what happens after rna processing
mrna leaves the nucleus through a pore and enters a ribosome 5’ end first
what is the start codon
aug
what occurrs during translation
the mrna moves along the ribosome, the ribosome reads the mrna in codons, specific amino acids are then carried to the ribosome based of the trna’s anticodon being complementary to the codon, the anticodon then temporarily binds to the codon, this process continues until the termination sequence is reached, joining each amino acid to the next by peptide bonds
anticodon
a negative-sense sequence of three unpaired nucleotides in trna
codon
a positive sense sequence of three nucleotides in mrna and coding strand of dna
unambiguous
each codon specifies for only one amino acid
degenerate
most amino acids can be specified by more than one codon
what makes the specific protein from the gene
post transitional modification and exons spliced together
