Transcription summary notes
09 December 2022 13:31
1. DNA separates (unzips) at locus of the gene (hydrogen bonds between complementary
bases break)- bases on the template strand exposed
2. Complementary copy of the code from the gene is made by building mRNA (single
stranded molecule, has uracil instead of thymine) - RNA polymerase works from 3' to 5' on
template strand
3. This is because the free RNA nucleotides pair up with complementary bases on the
template strand of the unzipped DNA molecule
4. Sugar phosphate groups of RNA nucleotides are bonded together with phosphodiester
bonds using RNA polymerase
5. DNA strands re join behind RNA polymerase moving down the strand - so double stranded
DNA reforms
6. If no splicing- mRNA molecule leaves nucleus by nuclear pore
Eukaryotes:
1. Pre mRNA is spliced to remove introns (the non coding DNA base sequence within a gene)
by the spliceosome enzyme
2. Exons are joined together so the mRNA only contains exons and exists the nucleus by
nuclear pore
09 December 2022 13:31
1. DNA separates (unzips) at locus of the gene (hydrogen bonds between complementary
bases break)- bases on the template strand exposed
2. Complementary copy of the code from the gene is made by building mRNA (single
stranded molecule, has uracil instead of thymine) - RNA polymerase works from 3' to 5' on
template strand
3. This is because the free RNA nucleotides pair up with complementary bases on the
template strand of the unzipped DNA molecule
4. Sugar phosphate groups of RNA nucleotides are bonded together with phosphodiester
bonds using RNA polymerase
5. DNA strands re join behind RNA polymerase moving down the strand - so double stranded
DNA reforms
6. If no splicing- mRNA molecule leaves nucleus by nuclear pore
Eukaryotes:
1. Pre mRNA is spliced to remove introns (the non coding DNA base sequence within a gene)
by the spliceosome enzyme
2. Exons are joined together so the mRNA only contains exons and exists the nucleus by
nuclear pore
