Protein Synthesis Flashcards
What are proteins created on?
Ribosomes.
What are the two stages of protein synthesis?
Transcription and translation.
What is transcription?
Where a gene on the DNA is copied into mRNA.
Where does transcription occur?
In the nucleus.
Why does transcription occur?
So DNA doesn’t leave the nucleus and get damaged.
What is the first step of transcription?
The DNA helix unwinds to expose the 2 strands.
What happens to one strand from the unwinded helix in transcription?
It acts as a template to make mRNA as its single stranded.
What is the unwinding of the DNA helix catalysed by?
DNA helicase.
What does the DNA helicase do in transcription?
It breaks the hydrogen bonds between bases.
What happens after DNA helicase breaks the hydrogen bonds in transcription?
Free mRNA nucleotides in the nucleus align opposite exposed complementary bases.
What is the last step of transcription?
DNA polymerase bonds together the mRNA nucleotides to create a new RNA polymer chain (a gene).
What happens to the mRNA chain once its copied?
It’s modified and then leaves the nucleus.
What is modified into mRNA?
Pre-mRNA.
How is pre-mRNA modified into mRNA?
Its introns are spliced out by a protein called spliceosome.
What is translation?
Where mRNA attaches to a ribosome, and corresponding tRNA molecules bring the specific amino acid the codon codes for, creating a polypeptide chain.
What is the first step of translation?
The modified mRNA attaches to the ribosome in the cytoplasm.
Where does the ribosome attach to on the mRNA molecule in translation?
The start codon.
What does the tRNA molecule with the complimentary anticodon do in translation?
Aligns opposite the mRNA, held in place by the ribosome.
What does the ribosome do after tRNA has aligned opposite mRNA in translation and why?
It moves along the mRNA to enable another complimentary base to attch to the next codon on the mRNA.
What do amino acids join by?
A peptide bond.
What is a peptide bond catalysed by and what does the reaction require?
An enzyme, and ATP.
When does the ribosome stop moving down the mRNA molecule?
When it reaches the stop codon at the end of mRNA.
What does the ribosome do when it reaches the stop codon?
It detaches from mRNA.
