5.k./l. Transcription Flashcards
Define ‘transcription’
3 points
- When a segment of DNA acts as a template
- to direct the synthesis of a complementary sequence of RNA
- with the enzyme RNA polymerase
Where does transcription take place?
In the nucleus
What does the newly synthesised mRNA carry? From and to what?
- Newly synthesised mRNA carries the information for protein synthesis
- From the nucleus to the cytoplasm
What do ribosomes in the cytoplasm provide during transcription?
Provide a suitable surface for:
- The attachment of mRNA
- Protein synthesis
Summarise the 6 steps in the sequence of transcription
- DNA helicase breaks H-bonds
- RNA polymerase binds
- Free RNA nucleotides align
- RNA polymerase moves along DNA
- RNA polymerase separates
- New RNA detaches from the DNA
Expand: ‘DNA helicase breaks the H-bonds between…’ (2)
- Between the bases in a specific region of DNA
- And 2 strands unwind, exposing a nucleotide base
Expand: ‘RNA polymerase binds to the template of…’
Binds to the template strand of DNA at the beginning of the strand that’s going to be copied
Expand: ‘ Free RNA nucleotides align along the template strand based on…’
Based on the complementary relationship between the bases in the DNA and the free nucleotides (CtoG, AtoT)
Expand: ‘RNA polymerase moves along the DNA forming bonds which add…’
Which add RNA nucleotides (one at a time) to the growing RNA strand
What is the result of RNA polymerase moving along the DNA and adding RNA nucleotides? (2)
- Results in the synthesis of a molecule of mRNA alongside the unwound DNA strand
- DNA strands behind the polymerase rewind to reform the double helix
Expand: ‘RNA polymerase separates from…’
Separates from the template strand when it reaches a ‘stop’ signal
Why/When does the newly formed RNA detach from the DNA?
Because/when the production of the transcript is complete
