BIO NMDCAT

Mitochondria contain their own circular genome and ribosomes; mutations in their tRNA disrupt internal protein translation and ATP synthesis.

Expansins disrupt the non-covalent links between cellulose and hemicellulose, allowing turgor pressure to expand the primary cell wall.

Vinculin helps anchor internal actin microfilaments to transmembrane integrins, a structural link required for cell-matrix adhesion and motility.

While cellulose is built directly at the plasma membrane, matrix pectins and hemicelluloses are processed in the Golgi and shipped out via vesicles.

The symplast is the continuous web of living cytoplasm interconnected by plasmodesmata, allowing signaling molecules to travel throughout the plant.

CESA complexes are hexameric transmembrane rosette assemblies that extrude individual cellulose chains into the extracellular space.

The cytoskeletal core forms an internal structural framework that preserves the basic architecture of the cell even when the outer membrane is disrupted.

The mannose-6-phosphate tag acts as a molecular sorting signal that targets newly built hydrolytic enzymes to the lysosome.

Auxin stimulates proton pumps to drive H+ into the cell wall; the resulting drop in pH activates expansins, loosening the wall to allow turgor-driven growth.

Animal cells secrete a protein-rich extracellular matrix (featuring collagen, fibronectin, and laminin) that provides structural support while remaining flexible, unlike the carbohydrate-dominated cell walls of plants.

Tight junctions form a continuous fluid-tight seal between adjacent cell membranes, preventing materials from leaking between cells.

Without functional cellulose synthase complexes, the cell cannot build a primary cell wall, causing expanding cells to burst under turgor pressure.

The nucleolus functions as a ribosome manufacturing center, transcribing rRNA and combining it with proteins to form ribosomal subunits.

Inhibiting actin prevents the assembly of the contractile ring, blocking cleavage furrow formation and leaving the cell with two nuclei.

The smooth ER in hepatocytes contains cytochrome P450 enzyme families that chemically modify and detoxify hydrophobic drugs and toxins.

Proposed by Singer and Nicolson, the fluid mosaic model describes the membrane as a fluid phospholipid bilayer embedded with proteins.

Amyloplasts are a specific type of leukoplast that converts glucose into starch grains, storing them in roots, tubers, and seeds.

Polar molecules cannot pass through the hydrophobic lipid core directly; they require channel or carrier proteins to cross without using energy.

The stroma contains the soluble enzymes (such as RuBisCO) required to fix carbon dioxide into sugars during the Calvin cycle.