key info 2 for exams Flashcards
Key events in transcription:
and diagram
https://cognitoedu.org/coursesubtopic/b3-alevel-aqa_sEoImuSp
-RNA polymerase enzyme binds to DNA.
- hydrogen bonds between the DNA bases break, and the two strands of the double helix separate.
-The antisense strand acts as the template for mRNA synthesis.
-Free RNA nucleotides align with the DNA template through complementary base pairing.
-In the RNA molecule, uracil pairs with adenine from the DNA strand, while adenine from the RNA molecule pairs with thymine, and cytosine pairs with guanine.
-RNA polymerase catalyses the formation of phosphodiester bonds between adjacent RNA nucleotides.
- A complementary mRNA strand is formed, carrying the same base sequence as the DNA sense strand.
-The process ends when RNA polymerase reaches a stop codon, detaches from DNA and terminates transcription.
-mRNA is released, detaches from DNA, and DNA rewinds into its double helix structure.
what type of organisms’ (eukaryotes or prokaryotes) mRNA undergoes splicing? and what is splicing
In eukaryotes, pre-mRNA is spliced after transcription to remove introns(non coding bases) before it is transported to the cytoplasm but splicing doesn’t occur in prokaryotes.
