The Dynamic Cell: Compartments and Organelles

Vocabulary practice flashcards covering cell theory, cellular compartmentalisation, organelle structures, functions, and differences between prokaryotic and eukaryotic cells.

Cell Biology

The study of cell structure and function, centering on the concept that the cell is the fundamental unit of life and enabling a detailed understanding of tissues and organs.

Robert Hooke

The mid-1600s scientist who examined a sliver of cork under a microscope, described seeing a "row of empty boxes," and coined the term "cell."

Theodor Schwann

The scientist who proposed in 1839 that all living things are composed of cells.

Rudolf Virchow

The scientist who proposed in 1855 that all cells arise from pre-existing cells ("all cells come from cells").

Cell Theory

The foundational biological principle stating that all living creatures are made of one or more cells, the cell is the structural and functional unit of life, and all cells derive from pre-existing cells.

Prokaryotic Cells

Cells, encompassing bacteria and archaea, that lack a membrane-bound nucleus and contain organelles that are not enclosed by membranes.

Nucleoid

The region within a prokaryotic cell where DNA is concentrated without being enclosed by a membrane.

Eukaryotic Cells

Cells (including fungi, protists, plant, and animal cells) characterized by a membrane-bound nucleus and numerous membrane-enclosed organelles.

Cellular Compartmentalisation

The division of the eukaryotic cell interior into distinct membrane-enclosed compartments (organelles) to overcome larger diffusion distances and optimize chemical reaction efficiency.

Amphipathic Phospholipids

Molecules possessing both a hydrophilic (water-attracting) polar head and hydrophobic (water-repelling) nonpolar tails that spontaneously assemble into monolayers or bilayers.

Lipid Rafts

Microdomains within the plasma membrane bilayer where phospholipids and associated proteins drift laterally.

Cytoplasm

The viscous cellular contents outside the nucleus, composed of the cytosol, cytoskeleton, organelles, and storage substances.

Cytosol

The semifluid portion of the cytoplasm in which organelles and cytoskeletal elements are suspended.

Nucleus

The organelle enclosed by a double-membraned nuclear envelope with pore complexes, functioning as the site of cellular DNA storage, replication, and transcription.

Chromatin

The complex of genomic DNA packaged with histone proteins found within the nucleus.

Ribosomes

Non-membrane-bound complexes composed of RNA and protein that carry out protein synthesis either free in the cytosol or bound to the endoplasmic reticulum.

Smooth Endoplasmic Reticulum (Smooth ER)

A tubular region of the endoplasmic reticulum devoid of ribosomes, involved in carbohydrate metabolism, drug metabolism, and calcium ion movements.

Rough Endoplasmic Reticulum (Rough ER)

A region of the endoplasmic reticulum studded with ribosomes and continuous with the nuclear envelope, serving as the site of translation for proteins destined for membranes or secretion.

Golgi Apparatus

The membrane-stack packaging and shipping station of the cell that receives ER transport vesicles, modifies molecules, and pinches off new vesicles for delivery or exocytosis.

Mitochondria

Double-membrane-bound organelles containing their own DNA that break down organic compounds (glucose, fatty acids) via aerobic respiration to produce ATP.

Lysosomes

Membrane-bound organelles containing digestive enzymes that facilitate cell renewal, break down worn-out organelles (autophagy), and digest foreign invaders.

Peroxisomes

Organelles featuring a urate oxidase crystalline core and catalase that function in lipid synthesis, fatty acid oxidation, detoxification, and the metabolism of hydrogen peroxide ($\text{H}_2\text{O}_2$).

Cytoskeleton

A dynamic network of interconnected protein filaments and fibers that maintains cell shape, mediates motility, positions organelles, anchors cells, and segregates chromosomes during division.

Microtubules

Cylindrical cytoskeletal fibers measuring $25\,\text{nm}$ in diameter, composed of $\alpha$-tubulin and $\beta$-tubulin dimers, that act as structural supports and tracks for motor proteins.

Actin Filaments (Microfilaments)

Cytoskeletal fibers measuring approximately $7\,\text{nm}$ in diameter, formed from polymerized actin monomers, involved in cell shape and movement.

Intermediate Filaments

Rope-like cytoskeletal elements measuring $8\text{--}12\,\text{nm}$ in diameter made of fibrous subunits (such as neurofilaments in neurons) that provide mechanical stability.

Bacterial Chromosome

A single circular unit of naked DNA located in the nucleoid of a bacterium, lacking association with eukaryotic histone proteins.