Protein Synthesis Flashcards
What is the Central Dogma?
DNA leads to RNA leads to Protein
What is transcription?
First step in Central Dogma
Transcription is synthesis of mRNA from DNA
Occurs in nucleus
What is translation?
Second step of Central Dogma
Translation is synthesis of a polypeptide from mRNA
Ribosomes link AAs to mRNA.
What is a codon?
On mRNA, a codon is a unit of 3 bases (nucleotides).
The ribosome ‘reads’ each codon.
Each codon specififes an AA for the polypeptide.
What is meant by degeneracy of the codon?
Codons are redundnat.
2 or more codons may specify the same AA.
What is an anticodon?
It is part of tRNA.
tRNA brings an AA to the ribosome.
An anticodon is a nucleotide triplet.
The triplet is complementary to a codon on mRNA.
What is tRNA
transfer RNA
It brings an amino acid to the ribosome
The amino acid becomes part of the final polypeptide.
What is a missense codon?
A mutation on the codon leads to the wrong AA
What is a nonsense codon?
A mutated codon that results in something other than an AA.
For eg, the mutation creates a ‘stop’ codon.
How does translation stop?
Termination occurs because of a ‘stop’ codon.
A protein called ‘release factor’ binds to the codon.
The protein hydrolyzes the polypeptide/ribosome complex.
What are the 3 important sites on a ribosome’s large subunit?
A: new tRNA binding site
P: holds tRNA bound to polypeptide
E: exit site
What direction along mRNA does translation occur?
Ribosome moves along mRNA
5’ to 3’
What are the basic steps in transcription?
Initiation
Elongation
Termination
What happens during initiation step of transcription?
RNA polymerase binds to promoter region of DNA
What happens during elongation step of transcription?
RNA polymerase moves from 3’ to 5’ end of template strand.
This means mRNA transcript elongates 5’ to 3’
