Protein Synthesis: DNA Transcription

site of DNA transcription in eukaryotes

the nucleus

site of DNA transcription in prokaryotes

the cytoplasm

RNA polymerase function

synthesises complimentary RNA strand from DNA template by a dehydration reaction

template strand (AKA non-coding strand/ antisense strand/ minus strand)

DNA strand that RNA polymerase reads to synthesise mRNA

coding strand

DNA strand that is not read by RNA polymerase

difference between coding strand and RNA molecule

coding strand has thymine instead of uracil

mRNA

the strand RNA synthesised from the DNA template

promoter

site where RNA polymerase can bind to DNA and begin transcription

what does ‘m’ in mRNA stand for?

messenger

fate of mRNA after transcription

read by the ribosome for protein synthesis

exons

coding sequences

introns

non coding sequences

location of introns

found between exons

fates of exons and introns

exons are spliced, introns are excised

advantage of excising and splicing

allowing different exons to be spliced increases genetic diversity of proteins in an organism

last mRNA modification

addition of a 5’ GTP cap and a 3’ poly A tail

advantage of mRNA modification

protects mRNA from cellular enzymes that break down nucleic acids, help bind mRNA to ribosome for translation