Coconote
AI notes
AI voice & video notes
Export note
Try for free
Understanding the Translation Process
Nov 20, 2024
Lecture Notes on Translation Process
Overview
Translation Process:
Conversion of a gene into a protein.
Focus:
Big picture understanding of translation and mutations impacting phenotype.
RNA Codons
Codons:
Three base pair sequences in RNA language.
Universal Translation:
Nearly all organisms translate UUU to phenylalanine.
Codon Table Usage:
Helps determine amino acids from codons.
First letter determines the row.
Second letter determines the column.
Third letter specifies the exact amino acid.
Special Codons
Stop Codons:
UGA, UAA, UAG tell the cell to stop translation.
Start Codon:
AUG codes for methionine; starts translation.
Mutation Types
1. Silent Mutations
Definition:
Mutations with no effect on protein produced.
Example:
GGG in DNA → CCC in mRNA → Proline.
Mutating the last base pair to GGA → CCU still results in Proline.
Wobble Effect:
Flexibility in the third base pair often leads to silent mutations.
2. Missense Mutations
Definition:
DNA alterations changing the protein produced.
Example:
GAU (aspartic acid) → GUU (valine) after mutation.
Protein function may change but protein still produced.
Mutation in start codon can prevent translation.
3. Nonsense Mutations
Definition:
Mutation leads to a stop codon, truncating protein.
Example:
ACC (tryptophan) → ATC (stop codon) after mutation.
Results in incomplete, often nonfunctional protein.
4. Loss of Stop Mutations
Definition:
Mutates stop codon, removing stop signal.
Example:
ATT (stop) → UAC (amino acid) continues protein synthesis.
Often results in altered, sometimes nonfunctional proteins.
5. Frameshift Mutations
Definition:
Insertion or deletion of bases not in multiples of three.
Example:
Inserting T in GAG shifts reading frame, changes codons.
Can lead to nonsense or missense mutations.
Three-base insertions/deletions have less impact.
tRNA and Translation
tRNA Shape:
Clover-shaped with amino acid binding site.
Anticodon:
Region complementary to the mRNA codon, determining binding amino acid.
Ribosome Interaction:
tRNA interacts non-covalently with ribosomes.
Adds amino acids to the growing polypeptide chain.
Next Steps
Further details on translation machinery will be covered in future lectures.
📄
Full transcript