Chapter 4.14 Protein Folding and Secretion Flashcards
Once a protein is formed, a polypeptide folds to form a more ______ structure
Stable
What are the 4 different structures of a protein?
Primary Structure
Secondary Structure
Tertiary Structure
Quaternary Structure
What occurs in Secondary Structure?
Interactions of the R groups force the molecule to twist and fold in a certain way
Three-dimensional shape of polypeptide.
What structure of protein is best described by that?
Tertiary Structure
Quaternary structure entails what?
Number and types of polypeptides that make a protein
What and how does the denaturing (Denaturation) of a protein occur?
• Occurs when proteins are exposed to extremes of heat,
pH, or certain chemicals
• Causes the polypeptide chain to unfold
• Destroys the secondary, tertiary, and/or quaternary
structure of the protein
What is lost when a protein is denatured?
The Biological properties
Most polypeptides fold spontaneously in their active form, but some require assistance from what for folding to occur?
Molecular Chaperones or Chaperonins
- They only assist in the folding; they are not incorporated into protein
- Can also aid in refolding partially denatured proteins
What are found on proteins requiring transport from cell?
Signal sequences
Describe a signal sequence
- 15–20 residues long
- Found at the beginning of the protein molecule
- Signal the cell’s secretory system (Sec system)
- Prevent protein from completely folding
What system is for the secretion of folded proteins?
The Tat System
What is the Tat Protein Export System?
Proteins that fold in the cytoplasm are exported by a transport system distinct from Sec
- Iron–sulfur proteins
- Redox proteins
I don’t know how to make a card for this, so I’ll just type it on the back.
• Secretion of proteins -
• All are large complexes of proteins that form channels through membranes
• See Figure 4.43 for an example of how type III secretion in Gram – bacteria can act to inject proteins from the bacterium to a eukaryotic cell
