18 Questions
What is the function of dolichol phosphate molecule in protein glycosylation?
It acts as a carrier molecule to transfer sugars to proteins in the ER.
What happens to N-glycosylation in mutations that disrupt the protein translocation process?
N-glycosylation is delayed and inefficient due to improper protein folding.
Which best describes the role of Signal Recognition Particle (SRP) in protein synthesis?
SRP binds to the signal sequence and ribosome, aiding in targeting nascent proteins to the ER membrane.
What is the primary function of Rough Endoplasmic Reticulum (RER) in protein synthesis?
Involved in co-translational translocation of secretory and membrane proteins.
Which statement accurately describes the synthesis of integral membrane proteins?
Integral membrane proteins are co-translationally inserted into the ER membrane.
When SRP binds to both the signal sequence on nascent protein and ribosome, what is the next step in protein synthesis?
SRP-ribosome-nascent protein complex is recruited to the RER membrane.
What is the role of the translocon in protein synthesis?
Facilitates the movement of the nascent polypeptide from the ribosome to the ER lumen
How do G-proteins regulate protein synthesis in the context of the text?
By binding either GTP or GDP molecules and acting as molecular switches
What is the function of SRP in protein synthesis according to the text?
Guides ribosomes that are synthesizing membrane proteins to the ER membrane
Which statement accurately describes G-proteins in protein synthesis?
They act as molecular switches by changing conformation based on GTP or GDP binding
Which molecule is essential for N-glycosylation in protein synthesis?
Dolichol phosphate
What impact would mutations affecting N-glycosylation have on protein function?
Impaired protein folding and stability
How is the dolichol phosphate molecule involved in protein glycosylation?
It serves as the site for attachment of sugars on the cytosolic side of the membrane.
What happens once the oligosaccharide is completely assembled in glycosylation?
It is enzymatically transferred to an asparagine residue of the nascent polypeptide.
What is the consequence of mutations leading to total absence of N-glycosylation?
Death of embryos before implantation.
How are mutations affecting partial disruption of the glycosylation pathway in the ER different from mutations causing total absence of N-glycosylation?
They lead to serious inherited disorders affecting various organ systems.
In protein synthesis, what role does SRP (signal recognition particle) play?
It assists in targeting proteins to their correct cellular location.
What happens after the dolichol-PP is flipped back across the membrane during protein glycosylation?
It is ready to begin accepting sugars again.
This quiz covers the processes involved in protein synthesis and translocation in the endoplasmic reticulum (ER), including the movement of ribosomes to the translocon, the role of the translocon channel, and the interaction of the signal sequence with the translocon. It also includes information on GTP binding proteins and their regulation of certain steps.
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