Protein synthesis - Transciption Flashcards
What is protein synthesis?
Process where info contained within genetic material of DNA is transferred into protein
What is a gene?
Info required to produce entire protein
What dies protein synthesis start within?
Transcription, where an mRNA molecule is produced
Followed by translation, mRNA molecule used to produce specific amino acid sequence
Why is transcription necessary?
Not possible for large sections of DNA to leave nucleus (eukaryotic cells)
Transcription allows small copies of coding info to be made, which can travel to ribosomes for translation
What is the 1st step of transcription?
Section of DNA containing gene unwinds + is separated into 2 strands by DNA helicase
What are the strands called?
Template strand (which runs in 3’ to 5’ direction) + acts as template for complimentary mRNA strand
Other is called non-template strand + not involved in transcription
Whats the 2nd step of transcription?
Free RNA nucleotides (within nucleoplasm) pair with complimentary bases on template strand
What do RNA nucleotides not contain?
Thymine, so uracil nucleotides pair with exposed adenine bases on template strand
What is the 3rd step of transcription?
RNA polymerase forms phosphodiester bonds between adjacent RNA nucleotides, adding them in 3’ direction on mRNA molecule
Continues to end of section of DNA containing gene until mRNA detaches + leaves via nuclear pore
Whats the 4th step of transcription?
Section of DNA reforms as double helix due to hydrogen bonds reforming between complimentary bases on template + non template strand
How is transcription similar to DNA replication?
- Both include unwinding of DNA
- Both include hydrogen bonds reforming between complimentary bases
How is transcription different to DNA replication?
- In transcription, uracil pairs with adenine bases instead of thymine
- RNA nucleotides are involved
- RNA polymerase instead of DNA polymerase
