2.3.1 - Transcription Flashcards
What Is A Gene?
Sequence of nucleotide bases in a DNA molecule that codes for the production of a specific polypeptide.
What Is Transcription?
Where DNA is transcribed and an mRNA molecule is produced.
Describe mRNA
(3 Points)
~ Messenger RNA.
~ Made in the nucleus during transcription.
~ Carries the genetic code from the DNA in the nucleus to the cytoplasm.
Where Does Transcription Take Place?
In the nucleus.
Describe The Process Of Transcription
(9 Points)
1) RNA polymerase attaches to the DNA double-helix at the beginning of a gene (Start codon).
2) Hydrogen bonds between the two DNA strands in the gene break, separating the strands causing the DNA to unwind.
3) One of the strands is used as a template to make an mRNA copy.
4) RNA polymerase lines up free activated RNA mononucleotides alongside the template strand (Antisense strand) in complementary base pairs.
5) Once the RNA mononucleotides have paired up, they’re joined by RNA polymerase forming an mRNA molecule.
6) RNA polymerase moves along the DNA, separating the strands and assembling the mRNA strand.
7) The hydrogen bonds between the unwound strands of DNA re-form once the RNA polymerase has passed by and the strands wind back up into a double-helix.
8) When RNA polymerase reaches a stop codon, it stops making mRNA and detaches from the DNA.
9) The mRNA moves out of the nucleus through a nuclear pore and attaches to a ribosome in the cytoplasm, where translation takes place.
What Is The Anti-Sense Strand?
Template strand, used to produce mRNA.
What Is The Sense Strand?
Coding strand, non transcribed strand.
