topic 3- gene expression Flashcards
2 stages in gene expression
transcription and translation
what is gene expression
the process which the coded instructions of DNA are converted into functional proteins in our cells
3 types of RNA
mRNA. tRNA, rRNA
what does mRNA do
carries a copy of the DNA code from the nucleus to the ribosome
what does tRNA do
folds due to complementary base pairing. each tRNA molecule carries it’s specific amino acid to the ribosome
what does rRNA do
rRNA and proteins form the ribosome
what is transcription
the process where a primary mRNA transcript is produced from a molecule of DNA(nucleus)
what is translation
the synthesis of a protein from specific amino acids using the code in mRNA(ribosome)
what happens during RNA splicing
1-introns are removed
2-exons are spliced together to form the mature mRNA transcript
what happens during transcription
1-RNA polymerase moves along the DNA molecule unwinding the double helix and breaking the hydrogen bonds
2-one of the exposed DNA strands acts as a template
3-RNA polymerase synthesises a primary mRNA transcript by using free RNA nucleotides from the nucleus
what happens during translation
1-it’s initiated by start codons and ends on stop codons on the mRNA strand
2- anticodons bond to codons by complementary base pairing, translating the genetic code into a sequence of amino acids3- a polypeptide chain is formed
alternative RNA splicing
different mature RNA transcripts are produced from the same primary transcript depending on which exons are retained
