Transcription Flashcards
What is used to transfer genetic information from the nucleus to the cytoplasm
Messenger RNA (mRNA)
Describe structure of mRNA
Single stranded polynucleotide that coils into a single helix
What does mRNA length depend on
Depends on the length of the gene that has been transcribed
Describe the nucleotides of mRNA
Ribose sugar, phosphate group, nitrogenous base
What does the process of transcription involve
Forming of a single strand of mRNA from double stranded DNA
What is the first step of transcription
DNA double helix must first be unzipped and the hydrogen bonds broken
How is the DNA double helix unzipped and the hydrogen bonds broken
The reaction is catalysed by enzyme DNA helicase which moves along the sugar phosphate back bone starting at the start codon
What does the DNA helicase cause
DNA double helix is unzipped and the hydrogen bonds broken. This exposes a section of the coding sense strand and the template antisense strand
What the does the DNA template antisense strand act as
A template for the mRNA as free RNA nucleotides pair with the exposed complementary bases
What happens after free RNA nucleotides pair with the exposed complementary bases
RNA nucleotides are joined to adjacent nucleotides by phosphodiester bonds to form the mRNA strand
What is the joining of adjacent RNA nucleotides catalysed by
RNA polymerase
What happens when the transcription of the mRNA strand ends
The mRNA strand then detaches from the DNA allowing the double helix to reform
What is the mRNA the same as except one thing
mRNA will be same as sense coding strand except Thymine is replaced with uracil
