Practice Questions

The membrane network of the endoplasmic reticulum shares physical continuity with the outer nuclear membrane, allowing structural integration.

The rough endoplasmic reticulum (RER) derives its descriptive name directly from the attachment of membrane-bound ribosomes on its outer cytosolic side.

Because mRNA is kept away from ribosomes during synthesis, the cell can safely carry out splicing and capping before protein translation starts.

Exportins recognize cargo proteins tagged with an NES and form a complex with Ran-GTP to migrate out of the nucleus.

Euchromatin is the loosely packed, accessible form of DNA where RNA polymerase can readily bind to transcribe structural genes.

The inner nuclear membrane contains integral proteins (like LBR) that bind to the nuclear lamina to stabilize chromatin positioning.

Emerin is a vital inner nuclear membrane protein that anchors the nuclear lamina. Its loss disrupts nuclear structure, causing Emery-Dreifuss muscular dystrophy.

Nuclear transport does not use direct ATP/GTP hydrolysis at the transporter; instead, it relies on high Ran-GTP inside the nucleus and low Ran-GTP in the cytosol to maintain directionality.

Ran-GAP converts Ran-GTP to Ran-GDP in the cytosol, releasing importin to capture new cargo. Without it, the concentration gradient collapses, halting transport.

FG-nucleoporins (Phenylalanine-Glycine repeats) form a chaotic, flexible brush-like gel structure inside the pore that blocks large unchaperoned molecules.