anatomy 3

Plasma Membrane

Regulates what enters and leaves the cell, providing selective permeability and structural protection.

Nucleus

Stores genomic DNA and directs cellular activities including growth, metabolism, and protein synthesis.

Nucleolus

Dense region within the nuclear matrix responsible for producing and assembling ribosomal subunits.

Mitochondria

Generates the majority of chemical energy ($ATP$) for the cell through cellular respiration.

Ribosomes

Complexes of RNA and protein that synthesize polypeptides by translating mRNA transcripts.

Lysosomes

Membrane-bound organelles containing hydrolytic enzymes that digest cellular debris, worn-out organelles, and engulfed pathogens.

Centrioles

Paired cylindrical structures that organize the microtubule spindle apparatus to separate chromosomes during cell division.

Endoplasmic Reticulum

Network of membranous tubules and sacs involved in synthesizing lipids, processing proteins, and detoxifying metabolic wastes.

Golgi Apparatus

Stack of flattened cisternae that modifies, sorts, and packages macromolecules for secretion or delivery to other destinations.

Cilia

Short, numerous hair-like surface projections that beat rhythmically to move fluid, mucus, or debris across tissue surfaces.

Flagella

Long, whip-like cellular appendage that rotates or undulates to propel an entire cell forward.

Passive Transport

Net movement of substances across a biological membrane down a concentration gradient without the expenditure of cellular energy ($ATP$).

Diffusion

Spontaneous movement of solute particles from a region of higher concentration to a region of lower concentration until evenly distributed.

Osmosis

Net movement of water molecules across a selectively permeable membrane toward a region of higher solute concentration.

Filtration (Cellular)

Passage of fluid and dissolved solutes through a semipermeable membrane driven by a hydrostatic pressure gradient.

Active Transport

Movement of molecules or ions across a membrane against their concentration gradient, requiring transport proteins and cellular energy ($ATP$).

Ion Pump

Transmembrane carrier protein that uses energy from $ATP$ to move charged mineral ions across the membrane against an electrochemical gradient.

Phagocytosis

Type of endocytosis where the plasma membrane extends outward to engulf large solid particles, cellular debris, or microorganisms.

Pinocytosis

Type of endocytosis where the cell membrane invaginates to internalize small droplets of extracellular fluid and dissolved solutes.