Ch. 22b Post-Translational Processing & Genetic Code (Final Exam) Flashcards
Why does post-translational processing occur?
The polypeptide coming from the ribosome is inactive
What are the 4 structures of protein folding?
Primary, secondary, tertiary, and quarternary
Protein folding is aided by molecular chaperons. Where do they bind?
Hydrophobic regions of proteins
Why is chaperon binding important?
They keep protein in open conformation until it is ready to fold
What are the 2 functions of proteolytic cleavage?
1) Trimming to remove pieces of the N and/or C terminal to provide a shortened active protein
2) Cutting polypeptides into active protein segments
What drug is a common result of proteolytic cleavage?
Insulin
Post-translational chemical modification involves the…
Addition of small chemical functional groups to animo acids
What is the most common mode of chemical modification in animal cells?
Protein phosphorylation
Chemical modification promotes…
Protein diversity
What 3 amino acids are subjected to phosphorylation?
Serine, tyrosine, and theonine
What is the premise of protein degradation/ubiquitination?
Adding ubiquitin to misfolded proteins
What does the proteasome do once a protein is tagged with ubiquitin?
The proteasome recognizes the need for degradation into peptide subunits
In sum, how do post-translational mods affect proteins?
They change the structure, dynamics, behavior, and characteristics of proteins to allow for full activity
What do you call codons that code for the same amino acids?
Synonomous
Out of the 64 possible codons, how many represent amino acids, and how many are stop codons?
61 - represent
3 - stop codons