Chapter 03: Cells - Structure, Function, Transport, and the Cell Cycle

Comprehensive vocabulary flashcards covering the cell structure, organelles, membrane transport mechanisms, the cell cycle, mitosis, stem cells, cancer biology, and programmed cell death from Chapter 03.

Differentiated Cell

A cell that has developed specialized structural and functional characteristics to perform a specific bodily role.

Composite Cell

A hypothetical model cell that illustrates the structures, organelles, and components found in most typical cells.

Cytosol

The fluid portion of the cytoplasm in which organelles and other cellular structures are suspended.

Phospholipid Bilayer

The framework of the cell membrane, arranged with water-soluble (hydrophilic) phosphate heads facing outward and water-insoluble (hydrophobic) fatty acid tails facing the interior.

Signal Transduction

A process mediated by membrane receptor proteins that enables a cell to receive and respond to incoming external chemical messages.

Cellular Adhesion Molecules (CAMs)

Proteins on the cell surface that guide cells on the move, assist in cell adhesion, establish neural connections, and direct white blood cells to infection sites.

Selectins

Cellular adhesion molecules (CAMs) that coat white blood cells and provide friction to slow them down and anchor them to capillary walls.

Integrins

Cellular adhesion molecules (CAMs) that interact with adhesion receptor proteins to guide white blood cells through capillary walls toward infection sites.

Ribosomes

Non-membranous structures composed of protein and RNA that provide structural support and enzymatic activity to link amino acids together during protein synthesis.

Rough Endoplasmic Reticulum (Rough ER)

A tubular membrane network studded with ribosomes that participates in the synthesis and transport of proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

A tubular membrane network lacking ribosomes that conducts lipid synthesis and sugar synthesis.

Golgi Apparatus

A series of flattened membranous sacs that refines, packages, and delivers proteins synthesized on the rough endoplasmic reticulum.

Mitochondria

Membrane-bound, fluid-filled organelles with inner folds called cristae that extract energy from nutrients through cellular respiration to produce $ATP$.

Lysosomes

Small membranous sacs containing digestive enzymes that degrade proteins, carbohydrates, nucleic acids, bacteria, and worn-out cellular components.

Peroxisomes

Membranous sacs containing enzymes that break down lipids, alcohol, and hydrogen peroxide.

Microfilaments

Tiny rods of actin protein that create part of the cytoskeleton and provide cellular motility, such as in muscle contraction.

Microtubules

Hollow tubes composed of the protein tubulin that maintain cell shape, move organelles, and comprise cilia, flagella, and centrioles.

Centrosome

A non-membranous structure located in the cytoplasm near the nucleus consisting of two centrioles composed of microtubules, which produce spindle fibers during cell division.

Cilia

Motile, hairlike extensions of the cell membrane made of microtubules that beat in a coordinated back-and-forth manner to propel substances across cell surfaces.

Microvilli

Tiny extensions of the cell membrane composed of actin filaments that function to increase the surface area available for absorption.

Nuclear Envelope

A double-layered membrane perforated by nuclear pores that encloses the nucleus and separates nucleoplasm from cytoplasm.

Nucleolus

A dense, non-membranous body composed of RNA and protein within the nucleus that serves as the site of ribosome assembly.

Chromatin

A network of loosely coiled fibers consisting of DNA wound around protein molecules, carrying the genetic instructions for protein synthesis.

Diffusion

The passive movement of atoms, molecules, or ions from an area of higher concentration to an area of lower concentration due to continuous random thermal motion.

Facilitated Diffusion

A passive transport process in which water-soluble substances cross the cell membrane down their concentration gradient using specific ion channels or carrier proteins without expending $ATP$.

Osmosis

The passive diffusion of water across a selectively permeable membrane toward a region with a higher concentration of impermeant solute.

Osmotic Pressure

The potential pressure generated by osmosis capable of lifting a volume of water; it increases with higher solute concentrations.

Isotonic Solution

A solution having an osmotic pressure identical to intracellular fluid, causing no net movement of water into or out of the cell.

Hypertonic Solution

A solution with higher osmotic pressure (higher solute concentration) than the intracellular fluid, causing water to leave the cell and leading to cellular shrinkage (crenation).

Hypotonic Solution

A solution with lower osmotic pressure (lower solute concentration) than the intracellular fluid, causing water to enter the cell by osmosis and leading to cellular swelling or bursting (lysis).

Filtration

A passive process in which hydrostatic pressure (such as blood pressure) forces smaller molecules and water across a membrane while leaving larger molecules behind.

Active Transport

The movement of substances across a cell membrane against a concentration gradient (from low to high concentration) utilizing membrane carrier proteins and cellular energy ($ATP$).

$\text{Na}^+/\text{K}^+$ ATPase Pump

An active transport pump that consumes $ATP$ to expel three $\text{Na}^+$ ions from the intracellular fluid while importing two $\text{K}^+$ ions into the cell.

Pinocytosis

A type of endocytosis where the cell membrane indents and engulfs minute droplets of extracellular liquid into vesicles.

Phagocytosis

A form of endocytosis where the cell membrane invaginates to take up large solid particles, forming a phagosome that fuses with a lysosome for degradation.

Receptor-Mediated Endocytosis

A selective endocytic process in which specific extracellular ligands bind to cell membrane receptor proteins before being internalized into a vesicle.

Transcytosis

A transport mechanism combining endocytosis and exocytosis to rapidly ferry substances across a barrier formed by tightly joined epithelial cells.

Cell Cycle

The continuous sequence of events a cell undergoes from the time it forms until the time it divides, comprising interphase, mitosis, and cytokinesis.

Interphase

The active metabolic period between cell divisions during which the cell grows, maintains normal functions, replicates DNA, and duplicates organelles.

$S$ Phase

The synthesis phase of interphase during which the cell replicates its genetic material (DNA).

Prophase

The first stage of mitosis where chromatin condenses into distinct chromosomes, centrioles move to opposite poles, spindle fibers form, and the nucleolus and nuclear envelope disassemble.

Metaphase

The stage of mitosis in which spindle fibers attach to the centromeres of sister chromatids and align chromosomes along the cell equator (metaphase plate).

Anaphase

The mitotic stage where centromeres divide and sister chromatids separate into individual chromosomes, moving toward opposite poles as spindle fibers shorten.

Telophase

The final stage of mitosis during which chromosomes uncoil into chromatin, nuclear envelopes reform around daughter nuclei, nucleoli reappear, and the spindle apparatus breaks down.

Cytokinesis

The physical division of the cytoplasm that begins in anaphase and completes in telophase when an actin contractile ring forms a cleavage furrow that pinches the cell into two.

Telomeres

Repetitive non-coding DNA segments located at chromosome tips that shorten with each cell division, functioning as an internal mitotic clock.

Contact Inhibition

The regulatory phenomenon whereby normal cells cease dividing when they encounter adjacent cells and become crowded.

Oncogenes

Abnormal or overexpressed versions of genes that normally stimulate cell division, whose hyperactivation accelerates cell division and contributes to cancer development.

Tumor Suppressor Genes

Genes whose protein products normally inhibit cell division or trigger apoptosis; their inactivation or deletion allows unregulated mitosis.

Angiogenesis

The ability of a malignant tumor to stimulate the outgrowth of new local blood vessels to supply it with oxygen and nutrients.

Stem Cell

An unspecialized cell that can divide repeatedly to generate identical cells (self-renewal) or yield progenitor cells that differentiate into specialized cell types.

Progenitor Cell

A partially differentiated daughter cell derived from a stem cell that is committed to developing into a restricted set of specialized cell lineages.

Totipotent

A term describing cells (such as a fertilized egg and cells of the early cleavage embryo) that possess the developmental potential to produce any cell type in the body.

Pluripotent

A term describing stem cells occurring later in development whose daughter cells can differentiate into a limited range of specialized cell lineages.

Apoptosis

A programmed, orderly sequence of cellular suicide mediated by intracellular caspases that destroys specific cells during development and removes damaged tissues.

Necrosis

Disordered, non-physiological cell death resulting from acute injury, trauma, or pathology, differing fundamentally from programmed apoptosis.