Bio Chem Exam 3 ACTUAL
EXAM. GRADED A+. WITH
QUESTIONS AND 100%
VERIFIED ANSWERS. LATEST
2025/2026 UPDATE
what is a molecular chaperone - Ans✔✔-A protein that assists in the folding of
proteins
Where do chaperones bind - Ans✔✔-solvently exposed hydrophobic surfaces -
promote proper folding of aggregates
What do chaperones do - Ans✔✔-prevent/reverse improper associations,
especially in multi-domain and multi-subunit proteins
Why are chaperones needed - Ans✔✔-unfolded proteins in vivo have a great
tendency to form intramolecular and intermolecular aggregates
What do most chaperones require - Ans✔✔-Most require ATP
- most are ATPases
,List the 4 Classes of Chaperones - Ans✔✔-1. Heat shock proteins 70 (70 kD -
monomeric)
2. Chaperonins (form large multisubuit cage-like assemblies
- Cavity where missfolded proteins can be refolded
3. Hsp90 (abundant in eukaryotes)
4. Nucleoplasmins (acidic nuclear proteins involved in nucleosome assembly)
What are chaperonins? - Ans✔✔-protein molecules that assist the proper
folding of other proteins
What Chaperonin system is commonly used in bacteria - Ans✔✔-GroEL/ES
system
Composition of GroEL - Ans✔✔-GroEL:
- 14 identical subunits in two rings (creates a central cavity)
- 7 identical subunits in one donut (x2 donuts)
- symmetrical rings
Composition of GroES - Ans✔✔-GroES (cap):
- 7 subunit ring
GroEL/ES shape - Ans✔✔-
,How many subunits does the GroEL/ES system have? - Ans✔✔-21 total = 14
GroEL + 7 GroES
What is the cis ring - Ans✔✔-the ring that is bound to the GroES cap
- changes conformation when bound
- geometry shifts when capped (no-longer identical to other ring)
What is the trans ring - Ans✔✔-The rings that is not bound
What do all 7 subunits in the GroEL ring bind? - Ans✔✔-All bind ADP/ATP
- every cycle costs 7 ATP (cleaved into ADP_
- **costs less than degrading the protein and starting folding over**
How many domains does a singular GroEL subunit have? - Ans✔✔-3 domains
What are the 3 domains of the GroEL subunit? - Ans✔✔-1. Apical (A)
2. Intermediate (I)
3. Equitorial (E)
**each folds independently and are held together by linkers
, - the subunits undergo conformational changes to form linear form when ES
cap binds
In which domain does ADP/ATP bind - Ans✔✔-ATP is bound to the binding site
of the EQUATORIAL domain which then hydrolyses ATP into ADP causing the
conformational change in the rest of the subunit.
Which domains of GroEL move when ADP is bound? - Ans✔✔-- equatorial stays
still
- apical and intermediate shift/extend
- allows binding cap to bind
What do the hydrophobic patches on the apical domain do? - Ans✔✔-they
attract the missfolded protein (with its hydrophobic domains revealed)
ALSO, allows the binding of the GroES cap
- when conformation change happens, the hydrophobic residues become
accessible for the ES cap
**Apical domain has 12 amino acid residues with 8 of them being hydrophobic
- highly hydrophobic
Reaction cycle of GroEL/ES - Ans✔✔-**NOTE** - TRANS AND CIS RINGS FLIP AT
THE END
2 Models for GroEL/ES Action - Ans✔✔-1. Anfinsen cage model
EXAM. GRADED A+. WITH
QUESTIONS AND 100%
VERIFIED ANSWERS. LATEST
2025/2026 UPDATE
what is a molecular chaperone - Ans✔✔-A protein that assists in the folding of
proteins
Where do chaperones bind - Ans✔✔-solvently exposed hydrophobic surfaces -
promote proper folding of aggregates
What do chaperones do - Ans✔✔-prevent/reverse improper associations,
especially in multi-domain and multi-subunit proteins
Why are chaperones needed - Ans✔✔-unfolded proteins in vivo have a great
tendency to form intramolecular and intermolecular aggregates
What do most chaperones require - Ans✔✔-Most require ATP
- most are ATPases
,List the 4 Classes of Chaperones - Ans✔✔-1. Heat shock proteins 70 (70 kD -
monomeric)
2. Chaperonins (form large multisubuit cage-like assemblies
- Cavity where missfolded proteins can be refolded
3. Hsp90 (abundant in eukaryotes)
4. Nucleoplasmins (acidic nuclear proteins involved in nucleosome assembly)
What are chaperonins? - Ans✔✔-protein molecules that assist the proper
folding of other proteins
What Chaperonin system is commonly used in bacteria - Ans✔✔-GroEL/ES
system
Composition of GroEL - Ans✔✔-GroEL:
- 14 identical subunits in two rings (creates a central cavity)
- 7 identical subunits in one donut (x2 donuts)
- symmetrical rings
Composition of GroES - Ans✔✔-GroES (cap):
- 7 subunit ring
GroEL/ES shape - Ans✔✔-
,How many subunits does the GroEL/ES system have? - Ans✔✔-21 total = 14
GroEL + 7 GroES
What is the cis ring - Ans✔✔-the ring that is bound to the GroES cap
- changes conformation when bound
- geometry shifts when capped (no-longer identical to other ring)
What is the trans ring - Ans✔✔-The rings that is not bound
What do all 7 subunits in the GroEL ring bind? - Ans✔✔-All bind ADP/ATP
- every cycle costs 7 ATP (cleaved into ADP_
- **costs less than degrading the protein and starting folding over**
How many domains does a singular GroEL subunit have? - Ans✔✔-3 domains
What are the 3 domains of the GroEL subunit? - Ans✔✔-1. Apical (A)
2. Intermediate (I)
3. Equitorial (E)
**each folds independently and are held together by linkers
, - the subunits undergo conformational changes to form linear form when ES
cap binds
In which domain does ADP/ATP bind - Ans✔✔-ATP is bound to the binding site
of the EQUATORIAL domain which then hydrolyses ATP into ADP causing the
conformational change in the rest of the subunit.
Which domains of GroEL move when ADP is bound? - Ans✔✔-- equatorial stays
still
- apical and intermediate shift/extend
- allows binding cap to bind
What do the hydrophobic patches on the apical domain do? - Ans✔✔-they
attract the missfolded protein (with its hydrophobic domains revealed)
ALSO, allows the binding of the GroES cap
- when conformation change happens, the hydrophobic residues become
accessible for the ES cap
**Apical domain has 12 amino acid residues with 8 of them being hydrophobic
- highly hydrophobic
Reaction cycle of GroEL/ES - Ans✔✔-**NOTE** - TRANS AND CIS RINGS FLIP AT
THE END
2 Models for GroEL/ES Action - Ans✔✔-1. Anfinsen cage model
