The Cell and Its Functions Vocabulary

Vocabulary flashcards covering cellular structure, organelle functions, energy production, ingestion mechanisms, and cellular locomotion based on Chapter 2.

Protoplasm

The collective term for the five basic substances that make up the cell: water, electrolytes, proteins, lipids, and carbohydrates.

Structural Proteins

Proteins present in the cell mainly as long filaments that form microstructures, such as the cytoskeleton, cilia, nerve axons, and extracellular collagen or elastin fibers.

Functional Proteins

Mobile or membrane-bound proteins in tubular-globular form that function primarily as enzymes to catalyze specific intracellular chemical reactions.

Triglycerides

Also called neutral fat, these lipids account for up to $95\,\text{percent}$ of fat cell mass and represent the body's main storehouse of energy-giving nutrients.

Glycogen

An insoluble polymer of glucose stored inside cells that can be rapidly depolymerized to supply the cell's energy needs.

Cell Membrane

A pliable structure $7.5\text{ to }10\,\text{nanometers}$ thick composed of approximately $55\,\text{percent}$ proteins, $25\,\text{percent}$ phospholipids, $13\,\text{percent}$ cholesterol, $4\,\text{percent}$ other lipids, and $3\,\text{percent}$ carbohydrates.

Lipid Bilayer

A thin, double-layered film of lipids continuous over the cell surface, with hydrophilic phosphate heads facing the outer surfaces and hydrophobic fatty acid tails facing the middle.

Sphingolipids

Lipids derived from the amino alcohol sphingosine that contain hydrophobic and hydrophilic groups and serve functions such as signal transmission, protection, and protein adhesion.

Integral Proteins

Cell membrane proteins that protrude all the way through the lipid bilayer, functioning as structural channels, carrier proteins, enzymes, or signal receptors.

Peripheral Proteins

Cell membrane proteins attached to one surface of the membrane without penetrating it, acting almost entirely as enzymes or controllers of transport through membrane pores.

Glycocalyx

A loose carbohydrate coat covering the outer surface of the cell, composed of the carbohydrate portions of glycoproteins, glycolipids, and proteoglycans.

Cytosol

The jelly-like fluid portion of the cytoplasm containing dissolved proteins, electrolytes, and glucose in which particles and organelles are dispersed.

Granular Endoplasmic Reticulum

The portion of the endoplasmic reticulum studded with ribosomes on its outer membrane surface, responsible for synthesizing protein molecules.

Agranular Endoplasmic Reticulum

The smooth portion of the endoplasmic reticulum without attached ribosomes, responsible for lipid synthesis and various intrareticular enzymatic detoxification processes.

Golgi Apparatus

An organelle composed of stacked, flat vesicles near the nucleus that works with the endoplasmic reticulum to process, compact, and package synthesized substances into transport vesicles.

Lysosomes

Vesicular organelles formed by the Golgi apparatus that are $250\text{ to }750\,\text{nanometers}$ in diameter and contain up to $40$ hydrolytic enzymes for intracellular digestion.

Peroxisomes

Organelles formed by self-replication or budding from the smooth ER that contain oxidases and catalase to generate and utilize $H_2O_2$ for detoxifying harmful substances and catabolizing long-chain fatty acids.

Secretory Vesicles

Storage vesicles formed by the ER-Golgi apparatus system that hold proenzymes or other chemical substances prior to their secretion outside the cell.

Mitochondria

Known as the powerhouses of the cell, these self-replicating organelles contain their own DNA and generate over $95\,\text{percent}$ of the cell's ATP via the citric acid cycle and oxidative phosphorylation.

Cristae

Infoldings of the inner mitochondrial membrane that provide a large surface area for attached oxidative enzymes involved in ATP synthesis.

Microtubules

Stiff tubular structures composed of polymerized tubulin molecules that form the cellular cytoskeleton, centrioles, mitotic spindles, and core structures of cilia.

Nucleolus

A non-membrane-bound structure within the nucleus consisting of accumulated RNA and proteins where ribosome formation begins.

Endocytosis

The process by which large particles or macromolecules enter the cell, primarily classified into pinocytosis and phagocytosis.

Pinocytosis

The ingestion of minute particles and extracellular fluid into vesicles $100\text{ to }200\,\text{nanometers}$ in diameter via clathrin-coated pits in the cell membrane.

Phagocytosis

The ingestion of large particles, such as bacteria, tissue debris, or whole cells, by specialized cells using membrane evagination and receptor-ligand attachment.

Autophagy

A housekeeping process by which worn-out cellular organelles and protein aggregates are enclosed in autophagosomes and delivered to lysosomes for degradation and recycling.

Autolysis

The complete self-digestion of a severely damaged cell caused by the mass rupture of its lysosomes and release of hydrolytic enzymes.

Exocytosis

The process by which secretory or residual vesicles fuse with the cell membrane and release their contents to the cell exterior, usually triggered by calcium ion entry.

Adenosine Triphosphate (ATP)

A high-energy nucleotide composed of adenine, ribose, and three phosphate radicals, whose labile bonds release about $12,000\,\text{calories per mole}$ to power cellular functions.

Chemotaxis

The movement of a cell toward (positive) or away from (negative) a chemical substance in response to a concentration gradient.

Axoneme

The structural framework of a cilium consisting of $9$ double tubules surrounding $2$ central single tubules linked together by protein cross-linkages.

Dynein

Protein arms with ATPase activity located on ciliary double tubules that crawl along adjacent tubules to produce bending and whiplike ciliary movement.