Cell Biology: Mitochondria and Rough Endoplasmic Reticulum

Comprehensive vocabulary flashcards covering the structure, function, staining, and genetics of mitochondria, as well as the morphology and functions of the rough endoplasmic reticulum.

Mitochondria

Membrane-enclosed organelles considered the power house of the cell (from Greek mitos = thread + chondros = granule) that rapidly change shape, fuse, divide, and move along microtubules.

Iron hematoxylin

A special histological stain with which mitochondria appear dark blue under the light microscope.

Janus green

A special stain under which mitochondria appear green in colour when viewed with a light microscope.

Porins

Transmembrane proteins located in the smooth, sieve-like outer mitochondrial membrane that form channels for small molecules to pass from the cytoplasm into the intermembrane space.

Cristae

A series of long infoldings of the inner mitochondrial membrane that project into the matrix and greatly increase the membrane's surface area in proportion to cellular energy needs.

Elementary particles

Protein complexes composed of a globular head attached to a narrow stalk studded on the inner mitochondrial membrane facing the matrix; they contain ATP synthase complexes for oxidative phosphorylation.

Mitochondrial matrix

The innermost mitochondrial compartment filled with a dense fluid composed of at least $50\%$ protein (mainly enzymes), circular DNA, ribosomes, mRNA, and tRNA.

Succinate dehydrogenase

The only enzyme of the Krebs (tricarboxylic acid [TCA]) cycle located on the inner mitochondrial membrane rather than in the matrix.

Matrix granules

Electron-dense structures in the mitochondrial matrix composed of phospholipoprotein that can also bind magnesium and calcium, especially in bone and cartilage cells.

Mitochondrial fission

The process of simple division by which mitochondria reproduce and increase their number.

Maternal inheritance

The inheritance pattern specific to mitochondrial DNA mutations, passed exclusively through the mother, unlike nuclear DNA mutations which can derive from either or both parents.

Endoplasmic Reticulum

An anastomosing network of intercommunicating channels and sacs formed by a continuous membrane enclosing an internal space called a cisterna.

Rough endoplasmic reticulum (RER)

A membranous organelle consisting of saclike and parallel stacks of flattened cisternae studded with polyribosomes on its outer surface, prominent in protein-secreting cells.

Ribophorins

Specific membrane receptors present on rough endoplasmic reticulum membranes that bind the large ribosomal subunit.

Transfer vesicles

Membranous vesicles that bud off from RER cisternae to package newly synthesized proteins and deliver them to the Golgi apparatus.