MCQs

Mitochondrial outer membrane permeabilization releases Cytochrome c into the cytosol, where it activates the apoptosome and executioner caspases.

The electron transport chain pumps protons into the intermembrane space, building a proton-motive force (proton electrochemical gradient) that drives ATP synthase mechanically.

Cardiolipin is a double-phospholipid compound unique to the inner mitochondrial membrane that acts as an electrical insulator to block proton leakage.

Mitochondria are the powerhouses of the cell because they regenerate adenosine triphosphate (ATP) from ADP and inorganic phosphate.

Mitochondria possess independent circular DNA genomes and bacterial-like 70S ribosomes, allowing independent transcription and translation of select proteins.

The matrix is the gel-like central compartment of the mitochondrion where the Krebs cycle takes place. Stroma is found in chloroplasts.

Cristae are folds of the inner mitochondrial membrane that house the respiratory chain and ATP synthase complexes.

The sulfation of proteoglycans and proteins is a specialized maturation step carried out by sulfotransferase enzymes located in the trans-Golgi.

Rab GTPases serve as molecular tags on transport vesicles, interacting with specific tethering complexes on target membranes to ensure docking accuracy.

The Golgi has a slightly lower pH than the ER. This acidic environment increases the affinity of KDEL receptors for ER proteins, facilitating their capture into retrograde COPI vesicles.

Without the mannose-6-phosphate (M6P) tag, lysosomal enzymes miss their sorting receptors in the trans-Golgi, routing into the default secretory pathway instead (I-cell disease).

The trans-Golgi network is the sorting hub where exit vesicles are packaged and targeted to the plasma membrane, lysosomes, or extracellular space.

While N-linked glycosylation begins in the ER, O-linked glycosylation occurs exclusively within the compartments of the Golgi apparatus.

The cisternal maturation model states that cis-cisternae physically mature into medial and then trans-cisternae, receiving recycling enzymes from behind via COPI vesicles.

Golgi apparatus stacks (dictyosomes) synthesize non-cellulosic polysaccharides and send secretory vesicles to form the phragmoplast and cell plate.

COPI-coated vesicles handle retrograde vesicle transport, moving materials backward from the Golgi to the ER.

Primary lysosomes emerge as transport vesicles from the trans-Golgi network carrying concentrated mixtures of active hydrolytic enzymes.

Lysosomal enzymes are specifically modified with a mannose-6-phosphate (M6P) tag in the cis-Golgi, which is recognized by M6P receptors in the trans-Golgi for sorting.

As proteins move from the cis to the trans face, their attached sugar groups undergo sequential enzymatic modifications to form mature complex glycoproteins.