8.4 Polypeptide synthesis - transcription and splicing Flashcards
What is transcription?
The production of mRNA from DNA.
What is the strand that is used for transcription called?
Template strand
What is the strand that is not used for transcription called?
Coding strand
What is the enzyme called that breaks hydrogen bonds between bases?
DNA helicase
What is the enzyme called that joins free nucleotides together to form a pre-mRNA?
RNA polymerase
What are the stages of transcription?
- DNA helicase (enzyme) binds to DNA
- hydrogen bonds between the DNA bases break, and the two strands of the double helix separate
- the template strand pairs with free RNA nucleotides through complementary base pairing
- in RNA molecule, A pairs with U and C pairs with G
- RNA polymerase (enzyme) joins free nucleotides together to form a pre-mRNA
- as RNA polymerase joins free nucleotides together, the two DNA strands rejoin behind it
- when RNA polymerase reaches a particular sequence of bases on the DNA called terminator sequence, it detaches (分離) from the DNA and the production of pre-mRNA is complete
What is the function of DNA helicase?
Breaking hydrogen bonds that link the bases together
What is the function of RNA polymerase?
Joining free nucleotides together to form a pre-mRNA molecule
In prokaryotic cells, what does transcription result in?
Production of mRNA
In eukaryotic cells, what does transcription result in?
Production of pre-mRNA
In eukaryotic cells, what happens after transcription in order to produce mRNA?
Splicing
What is splicing?
Removing introns and joining exons together.
In eukaryotic cells, what happens after splicing?
mRNA is produced and it leaves the nucleus via the nuclear pore.
In eukaryotic cells, what does the mRNA do after leaving the nucleus?
It is attracted to the ribosome and translation can be started.
