Cytoplasm & Organelles: Integrated Human Anatomy & Physiology

Vocabulary practice flashcards covering cell structure, organelles, chemical reactions, cellular respiration, metabolic pathways, and cytoskeletal components from Unit 5.

Cytoplasm

The interior cellular material consisting of cytosol (fluid solvent and solutes) plus organelles (‒little organs‒).

Cytosol

The fluid solvent (water) and solutes (salts such as $\text{Na}^+$, $\text{K}^+$, $\text{Cl}^-$, mono- and diglycerides, and proteins) dissolved within the cell.

Mitochondrion

The double-membrane organelle responsible for energy production ($\text{ATP}$ factory) consisting of an outer membrane, inner membrane, intermembrane space, and matrix.

mtDNA

Mitochondrial DNA located inside the mitochondrial matrix that is passed strictly from mother to daughter and mother to son.

Endergonic Reaction

An anabolic chemical reaction that requires energy input and absorbs energy into chemical bonds to combine simple molecules into complex molecules.

Exergonic Reaction

A catabolic chemical reaction that releases energy from chemical bonds when breaking down complex molecules into simple ones to perform work.

Metabolism

The controlled, multi-step process in which energy released during catabolism is captured and stored in $\text{ATP}$, with uncaptured energy lost as heat.

Cellular Respiration

The multi-step oxidation of glucose to produce $\text{ATP}$, represented by the chemical equation $\text{C}_6\text{H}_{12}\text{O}_6 + 6\,\text{O}_2 \rightarrow 6\,\text{CO}_2 + 6\,\text{H}_2\text{O} + 26\text{-}38\,\text{ATP}$.

Pyruvic Acid (Pyruvate)

A 3-carbon sugar molecule ($\text{C}_3\text{H}_4\text{O}_3$) formed by splitting glucose during glycolysis; present in non-ionized (acid) or ionized (-ate) forms.

Coenzyme A (CoA)

A recycled coenzyme acting as a ‒two-carbon carrier shovel‒ that delivers acetyl groups into the citric acid cycle furnace.

FAD and NAD+

Recycled cofactors that serve as proton ($\text{H}^+$) and electron ($\text{e}^-$) carriers, transporting high-energy particles to the electron transport chain.

Glycolysis

The initial anaerobic step of cellular respiration occurring in the cytoplasm that splits 1 glucose into 2 pyruvates, yielding a net output of $2\,\text{ATP}$ and $2\,\text{NADH}$.

Anaerobic Respiration

A cellular pathway operating without oxygen where 1 glucose is converted to 2 pyruvates and then 2 lactates, producing a dead end with only $2\,\text{ATP}$ net.

Formation of Acetyl-Coenzyme A

The second step of cellular respiration in the mitochondrial matrix that processes pyruvate into acetyl-CoA, releasing $1\,\text{CO}_2$ and $1\,\text{NADH} + \text{H}^+$ per pyruvate.

Citric Acid Cycle

A cyclic pathway in the mitochondrial matrix (also called Krebs or TCA cycle) that yields $2\,\text{CO}_2$, $3\,\text{NADH} + 3\,\text{H}^+$, $1\,\text{FADH}_2$, and $1\,\text{ATP}$ per turn ($2\times$ per glucose).

Electron Transport Chain

Transmembrane complexes on the inner mitochondrial membrane that use high-energy electrons to pump protons into the intermembrane space, driving $\text{ATP}$ synthesis.

ATP Synthase

A membrane enzyme complex that converts the energy of protons flowing down their concentration gradient into chemical energy stored in $\text{ATP}$.

Glycogen

A branched glucose storage polymer primarily stored in the liver ($70\text{-}100\,\text{g}$) and skeletal muscle ($200\text{-}400\,\text{g}$) for readily available energy.

Gluconeogenesis

The metabolic creation of new glucose molecules from non-carbohydrate sources (fats or proteins), functioning essentially as glycolysis in reverse.

Cytoskeleton

The protein network of a cell providing structural stability, enabling movement of internal substances, and facilitating overall cell motility.

Microfilaments

The smallest cytoskeletal components ($7\text{-}8\,\text{nm}$ diameter), composed of double-stranded globular actin (G-actin) formed into filamentous actin (F-actin).

Intermediate Filaments

Cytoskeletal fibers ($8\text{-}12\,\text{nm}$ diameter) made from wound protein strands (such as keratin, neurofilaments, or GFAP) that provide structural reinforcement.

Microtubules

Hollow cytoskeletal tubes ($25\,\text{nm}$ diameter) formed from $\alpha$-tubulin and $\beta$-tubulin dimers and stabilized by microtubule-associated proteins (MAPs).

Centrosome

A microtubule-organizing center (MTOC) consisting of pericentriolar material and two centrioles (each composed of a $9 \times 3$ microtubule triplet arrangement).

Microvilli

Non-motile, finger-like cell projections with an actin microfilament core that maximize surface area for absorptive cells like intestinal epithelia.

Cilia

Hair-like cell extensions containing a $9\text{ doublets} + 2\text{ singlets}$ microtubule body that move fluids across a stationary cell surface using a power stroke and return stroke.

Flagellum

A whip-like cell projection with a microtubule core that moves a cell through fluid using a propeller motion; found in humans exclusively on sperm cells.

Spliceosome

An RNA-editing organelle complex that removes unwanted non-coding introns as loops and splices coding exons together to form mature messenger RNA (mRNA).

Ribosome

A two-subunit organelle composed of a $60\text{S}$ large subunit and a $40\text{S}$ small subunit that synthesizes proteins either freely in the cytoplasm or bound to the rough ER.

Rough Endoplasmic Reticulum (RER)

A membrane network studded with ribosomes that synthesizes proteins destined for export by exocytosis, cell membrane insertion, or packaging in lysosomes.

Smooth Endoplasmic Reticulum (SER)

A ribosome-free membrane network involved in lipid synthesis, drug and toxin processing, or calcium storage (sarcoplasmic reticulum in muscle).

Golgi Complex

An organelle composed of flattened cisternae that receives proteins at its cis (entry) face, finishes/packages them, and releases them at its trans (exit) face in secretory vesicles.

Endomembrane System

The continuous synthetic pathway spanning from nuclear DNA to RNA transcription, spliceosomes, RER translation, and Golgi packaging to final protein export or membrane insertion.

Lysosome

A membrane-bound digestive organelle containing lysozyme and acidic-optimal hydrolytic enzymes maintaining an internal pH of $\approx 5$ to break down waste.

Peroxisome

A membrane-bound organelle with a crystalline enzyme core that uses hydrogen peroxide ($\text{H}_2\text{O}_2$) and oxidases for $\beta$-oxidation of fatty acids, breaking down excess $\text{H}_2\text{O}_2$ via catalase.

Proteasome

A barrel-shaped digestive organelle complex that breaks down misfolded, temporary, or unneeded cellular proteins tagged by ubiquitin.