GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Other Protein Regulation
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
Example Questions
Example Question #101 : Cell Biology
How do Bax and Bak promote cell death?
They allow the release of cytochrome c from the mitochondria into the cytosol, which activates procaspase
They are a major component of the apoptosome
They bind and block Bcl2 from inhibiting Bax and Bak activators
They cleave procaspase into caspase, which initiates the caspase cascade
They allow the release of cytochrome c from the mitochondria into the cytosol, which activates procaspase
Bax and Bak dimerize to form a pore in the mitochondria outer membrane, which allows cytochrome c to escape into the cytosol. When cytochrome c is found in the cytosol, procaspase becomes activated and is cleaved into caspase. Once the caspase cascade begins the cell is destined for death.
Bax and Bak have nothing to do with the apoptosome and, while Bcl2 does block Bax and Bak from dimerizing, Bax and Bak do not prevent the action of Bcl2.
Example Question #1 : Help With Other Protein Regulation
What is the key functional difference between GEFs (guanine nucleotide exchange factors) and GAPs (GTPase activating proteins)?
GEFs are cytosolic and act on proteins there, while GAPs are nuclear and act on proteins within the nucleus.
GEFs 'activate' small GTPases and GAPs 'deactivate' small GTPases.
GEFs add guanine nucleotides to small GTPases and GAPs cleave them to promote activation.
GEFs 'deactivate' small GTPases and GAPs 'activate' small GTPases.
GEFs and GAPs have no functional difference, only slight differences in structure.
GEFs 'activate' small GTPases and GAPs 'deactivate' small GTPases.
A GEF activates a small GTPase by exchanging a bound GDP (which confers an inactive state) for a GTP (which is higher energy, and activates the protein). A GAP performs the opposite; GAPs enhance the intrinsic GTPase activity of the small GTPase, which causes hydrolysis of the GTP on the active protein, thus converting it back to GDP and an inactive state.
Example Question #43 : Cellular Processes
One commonly studied outcome of G protein-coupled receptor (GPCR) activation is the activation of phospholipase C (PLC). What two important second messengers are formed when PLC cleaves phosphoinositide-4,5-bisphosphate 
Protein kinase C (PKC) and
Protein kinase C (PKC) and
Interactions between 
Example Question #42 : Cellular Processes
What provides the necessary information to specify the three dimensional shape of proteins?
The amino acid sequence
The proteins peptide bonds
Specific hydrogen bonds
The proteins interactions with chaperone proteins
The protein's interactions with other polypeptides
The amino acid sequence
Proteins have different level of protein structure, termed primary, secondary, and tertiary (quarternary is also a type in certain proteins). The 3D shape of proteins is largely due to the tertiary structure of a protein. This level is dictated by the specific amino acid sequence of the protein.
All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
