Cell Structures, Functions & Transport – Vocabulary Flashcards

Vocabulary flashcards covering key terms from lecture topics: cell structure, organelles, membrane components, transport mechanisms, animal & plant tissues.

Prokaryotic cell

Small cell lacking a true nucleus and membrane-bound organelles; DNA is circular and located in a nucleoid.

Eukaryotic cell

Larger cell with a true, membrane-bound nucleus and many membrane-bound organelles.

Nucleoid

Region in a prokaryote where circular, naked DNA resides.

Plasmid

Small, circular DNA molecule in bacteria carrying accessory genes.

Peptidoglycan

Complex polymer forming the rigid cell wall of bacteria.

Mesosome

Infolding of prokaryotic plasma membrane associated with cell division; functionally similar to mitochondria.

Histone

Basic protein around which eukaryotic DNA coils to form chromatin.

Organelle

Specialized membrane-bound structure within a eukaryotic cell performing a specific function.

Plasma membrane

Selectively permeable phospholipid bilayer enclosing cell contents.

Nucleus

Organelle containing genetic material; controls cell activities and division.

Nucleolus

Dense region in nucleus where rRNA and ribosomal subunits are produced.

Rough Endoplasmic Reticulum (RER)

Flattened membrane network studded with ribosomes; packages and transports newly made proteins.

Smooth Endoplasmic Reticulum (SER)

Tubular membrane network without ribosomes; synthesizes lipids, detoxifies drugs, stores Ca²⁺.

Golgi body

Stack of flattened sacs that modifies, sorts and ships proteins and lipids from ER; forms lysosomes and secretory vesicles.

Lysosome

Vesicle containing hydrolytic enzymes for intracellular digestion, autophagy and autolysis.

Ribosome

Site of protein synthesis; free ribosomes make cytosolic proteins, RER-bound ribosomes make exported proteins.

Mitochondrion

Double-membrane organelle, site of aerobic cellular respiration and ATP production.

Chloroplast

Plant plastid where photosynthesis occurs; contains chlorophyll, thylakoids and stroma.

Centriole

Cylindrical microtubule pair organizing spindle fibers during animal cell division.

Endomembrane system

Interconnected membranes (nuclear envelope, ER, Golgi, lysosomes, vesicles, plasma membrane) that exchange materials via vesicles.

Fluid Mosaic Model

Describes plasma membrane as fluid phospholipid bilayer with embedded, mobile proteins forming a mosaic pattern.

Phospholipid

Amphipathic molecule with hydrophilic head and hydrophobic tails; forms membrane bilayers.

Integral protein

Protein embedded within the lipid bilayer; often functions as channel, carrier or receptor.

Peripheral protein

Protein loosely attached to membrane surface; involved in signaling or cytoskeleton attachment.

Glycoprotein

Protein with attached carbohydrate chain; key in cell-cell recognition.

Glycolipid

Lipid with attached carbohydrate; contributes to cell identity on outer membrane.

Cholesterol

Steroid wedged between phospholipids; regulates membrane fluidity and stability.

Selective permeability

Property allowing some substances to cross a membrane more easily than others.

Simple diffusion

Passive movement of small, non-polar molecules down a concentration gradient through the lipid bilayer.

Facilitated diffusion

Passive transport of ions or polar molecules via specific channel or carrier proteins.

Osmosis

Diffusion of water across a selectively permeable membrane from higher to lower water potential.

Isotonic solution

Solution with equal solute concentration to the cell; no net water movement.

Hypotonic solution

Solution with lower solute concentration (higher water potential) than the cell; water enters cell.

Hypertonic solution

Solution with higher solute concentration (lower water potential) than the cell; water leaves cell.

Hemolysis

Swelling and bursting of erythrocytes in hypotonic solution.

Crenation

Shrinking and shriveling of erythrocytes in hypertonic solution.

Plasmolysis

Detachment of plant plasma membrane from cell wall when placed in hypertonic solution.

Turgid

Condition of plant cell swollen with water in hypotonic environment; cell wall prevents bursting.

Water potential (Ψ)

Measure of potential energy of water; water moves from higher (less negative) to lower (more negative) Ψ.

Solute potential (Ψs)

Component of water potential due to dissolved solutes; always negative.

Pressure potential (Ψp)

Component of water potential due to physical pressure on solution or cell wall.

Active transport

Energy-requiring movement of substances against their concentration gradient via carrier proteins.

Sodium-Potassium pump

Active transport protein that expels 3 Na⁺ and imports 2 K⁺ per ATP, maintaining ion gradients in animal cells.

Endocytosis

Bulk transport process bringing substances into cell by vesicle formation.

Phagocytosis

Type of endocytosis where cell engulfs large particles or microbes forming a food vacuole.

Pinocytosis

Type of endocytosis involving uptake of extracellular fluid and dissolved solutes via small vesicles.

Exocytosis

Bulk transport process where vesicles fuse with plasma membrane to release contents outside cell.

Tissue

Group of similar cells performing a common function.

Epithelial tissue

Sheet of tightly packed cells lining organs and body surfaces.

Simple squamous epithelium

Single layer of flat cells facilitating diffusion; lines alveoli and blood vessels.

Simple cuboidal epithelium

Single layer of cube-shaped cells; specialized for secretion and absorption in kidney tubules, ducts.

Simple columnar epithelium

Single layer of tall cells; may bear microvilli or cilia; lines digestive tract, uterus, bronchi.

Motor neuron

Efferent nerve cell transmitting impulses from CNS to effectors (muscles or glands).

Smooth muscle

Spindle-shaped, non-striated involuntary muscle in walls of organs and blood vessels.

Connective tissue

Tissue that supports, protects and binds other tissues; includes blood, bone, cartilage, etc.

Blood

Fluid connective tissue composed of plasma, erythrocytes, leukocytes and platelets.

Erythrocyte

Red blood cell lacking nucleus; biconcave disc that transports O₂ and CO₂ via hemoglobin.

Leukocyte

White blood cell involved in immune defense; includes neutrophils, lymphocytes, etc.

Thrombocyte (Platelet)

Cell fragment that initiates blood clotting.

Apical meristem

Region of actively dividing cells at root and shoot tips responsible for primary growth.

Parenchyma

Living ground-tissue cells with thin walls; function in storage, photosynthesis and support.

Collenchyma

Living support tissue with unevenly thickened primary walls; provides flexibility to young stems.

Sclerenchyma

Dead support tissue with thick, lignified secondary walls; includes fibers and sclereids.

Xylem

Vascular tissue transporting water and minerals upward; composed of tracheids, vessel elements, fibers, parenchyma.

Tracheid

Elongated, tapered xylem cell with pits; transports water but less efficiently than vessels.

Vessel element

Wide xylem cell with perforated end plates forming continuous tubes for efficient water flow.

Phloem

Vascular tissue transporting sugars and other organics throughout plant.

Sieve tube element

Living phloem cell lacking nucleus, joined end-to-end; conducts sucrose via sieve plates.

Companion cell

Phloem cell with nucleus that supports and loads/unloads adjacent sieve tube element.

Endodermis

Single root cortex layer with Casparian strip controlling entry of water and solutes to vascular tissue.

Casparian strip

Band of suberin in endodermal cell walls blocking apoplastic flow, forcing substances through plasma membranes.

Plasmodesmata

Cytoplasmic channels through plant cell walls connecting adjacent cells for transport and communication.