Transcription Flashcards
when does transcription start
when RNA polymerase attaches to the DNA double-helix at the beginning of a gene
in eukaryotes what happens to the hydrogen bonds between the two DNA strands in the gene
they are broken by a DNA helicase attached to the RNA polymerase. This separates the strands and the DNA molecule uncoils at that point, exposing some of the bases
what happens after some of the bases are exposed
one of the strands is then used as a template to make an mRNA copy
what does RNA polymerase do to free RNA nucleotides
the RNA polymerase lines up free RNA nucleotides alongside the exposed bases on the template strand. The free bases are attracted to the exposed bases. specific complementary base pairing means that the mRNA strands ends up being a complementary copy of the DNA template strand
what happens once the RNA nucleotides have paired up with their specific bases on the DNA strand
they’re joined together by RNA polymerase forming an mRNA molecule
what does RNA do after an mRNA molecule is formed
RNA polymerase moves along the DNA separating the strands and assembling the mRNA strand
what happens after an mRNA strand is formed
the hydrogen bonds between the uncoiled strands of DNA re-form once the RNA polymerase has passed by and the strands coil back into a double helix
What happens when RNA reaches a particular sequence of DNA called a stop sequence
it stops making mRNA and detaches from the DNA
in eukaryotes where mRNA move out from
mRNA moves out of the nucleus through a nuclear pore and attaches to a ribosome in the cytoplasm ,where the next stage of protein synthesis takes place; translation
