Cell Biology Cytoplasmic Organelles and Structures

Vocabulary flashcards reviewing cellular organelles, structures, and their functions based on the lecture notes.

Gap junction

Interconnections where cells are linked by water-filled hollow cylinders called connexons, allowing ions and nutrients to be exchanged between adjacent cells such as heart muscle cells and digestive tract cells.

Connexons

Water-filled hollow cylinders that interconnect adjacent cells within gap junctions to allow exchange of ions and nutrients.

Endoplasmic reticulum (ER)

A complex network of interconnected membranes forming sacs, canals, and vesicles (the cisternae) connected to the nuclear membrane, which acts as a tubular communication system for molecular transport.

Rough ER (RER)

Endoplasmic reticulum with tiny spherical ribosomes attached to its outer membrane; functions in protein synthesis and acts as the cell's "membrane factory" by producing integral proteins and phospholipids.

Smooth ER (SER)

A continuation of the RER lacking attached ribosomes; contains enzymes involved in lipid synthesis and metabolism, synthesis of steroid-based hormones, detoxification, and calcium ion storage and release.

Ribosomes

Small granules composed of protein and ribosomal RNA (rRNA), located free in the cytoplasm or attached to the ER, responsible for protein synthesis.

Golgi apparatus

A stack of membranous sacs called cisternae located near the nucleus that acts as the "traffic director" of the cell by modifying, concentrating, packaging, and delivering proteins synthesized by the RER.

Cis face

The convex receiving side of the Golgi apparatus where membranous sacs carrying proteins from the ER fuse to the Golgi membrane.

Trans face

The outer "shipping" side of the Golgi apparatus where altered proteins are packaged into membranous vesicles.

Secretory vesicles

Vesicles or granules that migrate to the plasma membrane and discharge their contents to the outside of the cell by exocytosis.

Lysosomes

Membranous sacs containing hydrolytic (digestive) enzymes that remain in the cell to digest endocytosed particles, degrade old organelles, perform metabolic functions, break down non-useful tissues, and break down bone to release calcium ions into the blood.

Autolysis

The self-digestion of a cell resulting from the rupture of the lysosomal membrane, which can occur when deprived of oxygen or exposed to excessive amounts of Vitamin A.

Peroxisomes

Membranous sacs containing peroxidases and catalase enzymes; oxidases neutralize free radicals into hydrogen peroxide, which catalase then converts to water.

Mitochondria

Elongated, fluid-filled sacs with a two-layered membrane that act as the "powerhouses" of the cell, controlling reactions of cellular respiration to produce ATP, transform energy, and replicate via fission.

Cristae

Extensive partitions formed by folds of the inner mitochondrial membrane to which cellular respiration enzymes are connected.

Centrosome

An organelle consisting of two hollow centrioles positioned at right angles near the Golgi apparatus and nucleus, responsible for forming the mitotic spindle during cell reproduction and initiating cilia and flagella formation.

Centrioles

Two hollow cylinders within a centrosome, each composed of a pinwheel arrangement of nine triplets of microtubules.

Cilia

Many hair-like structures attached to basal bodies beneath the cell membrane containing a distinct microtubule pattern, moving in a "to-and-fro" motion to propel fluids over tissue surfaces.

Ciliary action

The "to-and-fro" motion of cilia used to propel fluids, such as mucus in respiratory tubes, over the surface of tissues.

Flagella

A single, long tail-like process on a cell (e.g., sperm) that exhibits an undulating, wavelike motion to propel the cell itself.

Basal bodies

Modified centrioles located just beneath the cell membrane to which cilia are attached.

Vesicles

Membranous sacs formed when a portion of the cell membrane folds inward and pinches off, usually containing enclosed material.