AP Bio Cell Organelles

Plasma Membrane

A thin, flexible phospholipid bilayer that forms an outer selective barrier, controlling the transport of substances into and out of the cell.

Cytoplasm

The entire region enclosed by the outer cell barrier, excluding the nuclear region, that houses cellular structures and serves as the medium for metabolic reactions.

Cytosol

The fluid, gel-like intracellular portion of the cell body in which organelles are suspended and solutes are dissolved.

Nucleus

The eukaryotic control center bounded by a double membrane that houses the cell's genetic instructions ($DNA$) and coordinates gene expression.

Nuclear Envelope

The specialized double lipid bilayer perforated by protein channels that encases the genetic control center and separates it from the cytoplasm.

Nucleolus

A prominent non-membrane structure located within the genetic core that synthesizes ribosomal $RNA$ ($rRNA$) and joins it with proteins to form ribosomal subunits.

Nuclear Pores

Large multiprotein complexes spanning the double membrane of the genetic compartment that regulate the bidirectional transit of macromolecules.

Ribosomes

Cellular structures composed of $rRNA$ and polypeptides that catalyze the synthesis of proteins by translating messenger $RNA$.

Rough Endoplasmic Reticulum (Rough ER)

A labyrinth of membrane-bound sacs and tubules studded with protein-synthesizing complexes that processes and sorts newly made secretory proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

A network of interconnected membranous tubules free of surface granules that synthesizes lipids, metabolizes carbohydrates, and detoxifies metabolic byproducts and drugs.

Golgi Apparatus

A stack of flat, membrane-delimited cisternae that receives, chemically modifies, concentrates, and packages proteins and lipids into transport carriers.

Transport Vesicles

Small, spherical membrane-delimited containers that shuttle proteins, lipids, and other cellular cargo between organelles and to the outer boundary.

Lysosomes

Acidic, membrane-enclosed organelles containing hydrolytic digestive enzymes that break down discarded macromolecules, damaged organelles, and ingested pathogens.

Peroxisomes

Specialized metabolic microbodies containing enzymes that oxidize organic substrates, produce and degrade hydrogen peroxide ($H_2O_2$), and break down fatty acid chains.

Mitochondria

Double-membrane cellular powerhouses with inner foldings (cristae) where cellular respiration takes place to generate adenosine triphosphate ($ATP$).

Chloroplasts

Double-membrane photosynthetic organelles in plants and algae that capture solar energy using green chlorophyll pigments to produce sugars.

Central Vacuole (Plants)

A massive internal fluid reservoir in plant cells that maintains hydrostatic turgor pressure and stores essential ions, nutrients, and secondary metabolites.

Vacuole (Animal Cells)

Small, scattered membrane-bound storage compartments in non-plant cells that temporarily sequester fluids, ingested nutrients, or cellular wastes.