Unit 2 Vocabulary Flashcards

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• 1) Active Transport — method of transporting material that requires energy.
  • Key concepts: moves substances against their concentration gradient; requires cellular energy (often ATP).
  • Significance: enables uptake of nutrients, removal of wastes, maintenance of ion gradients critical for cell function.
  • Related processes: Endocytosis and Exocytosis are examples of active transport (items 18 and 23/24).
• 2) Apoptosis — programmed cell death.
  • Key concepts: regulated, orderly dismantling of a cell, often to remove damaged or dangerous cells.
  • Significance: essential for development and maintaining organismal health by preventing malfunctioning cells from causing harm.
• 3) Aquaporin — channel protein that allows water through the membrane at a very high rate.
  • Key concepts: water selective transport; increases water permeability of the membrane.
  • Significance: crucial for rapid water movement in cells and tissues (e.g., kidney tubules, plant roots).
• 4) ATP — repeat from Unit 1.
  • Key concepts: adenosine triphosphate; energy currency of the cell.
  • Significance: powers many cellular processes including active transport, muscle contraction, and biosynthesis.
• 5) Cell membrane (plasma membrane) — a phospholipid bilayer that encloses the cell.
  • Key concepts: semipermeable barrier; contains embedded proteins (channels, pumps, receptors).
  • Significance: maintains internal environment, mediates communication, and controls movement of substances.
• 6) Cell Wall — a protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists.
  • Key concepts: rigid structural support; often made of cellulose (plants), peptidoglycan (bacteria).
  • Significance: provides shape, protection, and turgor support in plants; restricts expansion.
• 7) Centrioles — rod-like structure consisting of microtubules at the center of each animal cell centrosome.
  • Key concepts: organizing centers for microtubules during cell division.
  • Significance: important for proper spindle formation and chromosome separation in many animal cells.
• 8) Channel Protein — membrane protein that allows a substance to pass through its hollow core across the plasma membrane.
  • Key concepts: provide hydrophilic passage; can be selective for specific ions or molecules.
  • Significance: enables rapid, facilitated movement of substances down its gradient.
• 9) Chloroplast — plant cell organelle that carries out photosynthesis.
  • Key concepts: contains chlorophyll; site of light reactions and Calvin cycle in plants.
  • Significance: primary organelle for converting light energy into chemical energy stored in sugars.
• 10) Cholesterol — repeat from Unit 1; regulates membrane fluidity in response to temperature changes.
  • Key concepts: modulates membrane fluidity; prevents packing at low temps and limits excessive fluidity at high temps.
  • Significance: helps maintain membrane integrity and proper function across temperature ranges.
• 11) Common Ancestry — an organism that is the shared ancestral species from which two or more different species evolved.
  • Key concepts: evolutionary origin; basis for comparing traits across species.
  • Significance: underpins phylogenetic relationships and understanding of homologous structures.
• 12) Compartmentalization — the division of a eukaryotic cell into distinct, membrane-bound organelles, each with specialized functions, allowing different cellular processes to occur simultaneously in separate environments within the cell.
  • Key concepts: separation of incompatible processes; membrane-bound compartments.
  • Significance: enables complex metabolism and regulation within a single cell.
• 13) Concentration Gradient — area of high concentration adjacent to an area of low concentration.
  • Key concepts: driving force for diffusion and some forms of transport.
  • Significance: determines direction of passive movement of solutes.
• 14) Cytoskeleton — network of protein fibers that collectively maintain the shape of the cell, secure some organelles in specific positions, allow cytoplasm and vesicles to move within the cell, and enable unicellular organisms to move independently.
  • Key concepts: actin filaments, intermediate filaments, microtubules.
  • Significance: structural support, intracellular transport, cell motility.
• 15) Cytosol — gel-like material of the cytoplasm in which cell structures are suspended.
  • Key concepts: aqueous, crowded cytoplasmic matrix.
  • Significance: medium for diffusion of small molecules and organelle interactions.
• 16) Diffusion — passive process of transport of low-molecular weight material according to its concentration gradient.
  • Key concepts: no energy required; down its gradient.
  • Significance: fundamental mechanism for substance movement across membranes.
• 17) Double Membrane — a cellular organelle that is surrounded by two distinct lipid bilayer membranes.
  • Key concepts: inner and outer membranes (e.g., nucleus, mitochondria, chloroplasts).
  • Significance: creates distinct internal compartments and regulates transport between layers.
• 18) Endocytosis — type of active transport that moves substances, including fluids and particles into a cell.
  • Key concepts: vesicle-mediated intake; energy-dependent.
  • Significance: enables uptake of large molecules, nutrients, and particulate matter.

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• 19) Endoplasmic Reticulum — series of interconnected membranous structures within eukaryotic cells that collectively modify proteins and synthesize lipids.
  • Key concepts: rough ER (with ribosomes) and smooth ER (lacks ribosomes).
  • Significance: key site for protein synthesis, folding, and lipid metabolism; connects to Golgi.
• 20) Endosymbiosis — a relationship between two species in which one organism lives inside the cell or cells of another organism.
  • Key concepts: one organism lives within another; mutualistic or parasitic interactions.
  • Significance: foundational idea for the origin of mitochondria and plastids.
• 21) Endosymbiotic Theory — the theory that mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by a host cell. The engulfed cell and its host cell then evolved into a single organism.
  • Key concepts: secondary endosymbiosis can occur; evidence includes double membranes and own DNA.
  • Significance: explains origin of key organelles and eukaryotic complexity.
• 22) Eukaryotic Cell — cell that has a membrane-bound nucleus and several other membrane-bound compartments or sacs.
  • Key concepts: nucleus, organelles; complex internal organization.
  • Significance: supports intricate regulation and compartmentalization of cellular processes.
• 23) Exocytosis — process of passing bulk material out of a cell.
  • Key concepts: vesicles fuse with plasma membrane to release contents.
  • Significance: secretion of enzymes, hormones, and waste disposal.
• 24) Extracellular — outside of the cell.
  • Key concepts: external environment and extracellular matrix.
  • Significance: governs signaling, transport, and interactions with neighboring cells.
• 25) Facilitated Diffusion — the passage of molecules or ions down their electrochemical gradient across a membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure.
  • Key concepts: uses channel or carrier proteins; no metabolic energy used.
  • Significance: enables selective movement of substances that cannot freely diffuse.
• 26) Flagella — long hair-like structure that extends from the plasma membrane and is used to move the cell.
  • Key concepts: motility; whip-like motion.
  • Significance: helps single-celled organisms and some cells in tissues to swim.
• 27) Fluid Mosaic Model — describes the structure of plasma membrane as a mosaic of components including phospholipids, cholesterol, proteins, glycoproteins, and glycolipids (sugar chains attached to proteins or lipids) resulting in a fluid character (fluidity).
  • Key concepts: dynamic, heterogeneous lateral movement of components.
  • Significance: explains membrane flexibility, permeability, and protein function.
• 28) Glycolipid — combination of carbohydrates and lipids; facilitate cell-to-cell recognition and adhesion.
  • Key concepts: glycan head groups on lipids.
  • Significance: important for cell signaling and tissue organization.
• 29) Glycoprotein — combination of carbohydrates and proteins; allows for cross linking of cells, which gives tissues strength.
  • Key concepts: carbohydrate chains attached to proteins.
  • Significance: roles in cell recognition, signaling, and structural integrity of tissues.
• 30) Golgi Complex — eukaryotic organelle made up of a series of stacked membranes that sorts, tags, and packages proteins and lipids for distribution.
  • Key concepts: cis, medial, and trans faces; vesicle trafficking.
  • Significance: central to post-translational modification and sorting for secretion or delivery to destinations.
• 31) Heat exchange — the transfer of thermal energy between different parts of an organism or between an organism and its environment.
  • Key concepts: conduction, convection, radiation, evaporation.
  • Significance: affects metabolic rates, homeostasis, and organismal thermoregulation.
• 32) Homeostasis — ability to maintain equilibrium of appropriate bodily or cellular functions and consistent internal conditions.
  • Key concepts: feedback mechanisms; set points.
  • Significance: essential for survival across changing environments.
• 33) Hypertonic — situation in which extracellular fluid has a higher osmolarity than the fluid inside the cell, resulting in water moving out of the cell.
  • Key concepts: higher dissolved solute outside.
  • Significance: can cause cell shrinkage (crenation in animals) and plasmolysis in plant cells.
• 34) Hypotonic — situation in which extracellular fluid has a lower osmolarity than the fluid inside the cell, resulting in water moving into the cell.
  • Key concepts: lower dissolved solute outside.
  • Significance: can cause cell swelling and lysis if excessive.

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• 35) Integral Protein (transmembrane protein) — protein integrated into the membrane structure that interacts extensively with the hydrocarbon chains of membrane lipids and often spans the membrane; these proteins can be removed only by the disruption of the membrane by detergents.
  • Key concepts: spans the membrane; strong association with lipid bilayer.
  • Significance: many transporters, receptors, and channels are integral proteins.
• 36) Intracellular — inside of the cell.
  • Key concepts: located within the cell boundaries.
  • Significance: contrasts with extracellular and membrane-associated locations.
• 37) Ion pump — transport ions against a concentration gradient, requires the use of energy or ATP.
  • Key concepts: active transport; often electrogenic.
  • Significance: maintains essential ion gradients (e.g., Na+/K+ pump).
• 38) Isotonic — situation in which the extracellular fluid has the same osmolarity as the fluid inside the cell, resulting in no net movement of water into or out of the cell.
  • Key concepts: equilibrium of water movement.
  • Significance: stable cell volume is maintained.
• 39) Lysosome — a membrane enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists.
  • Key concepts: digestive organelle; breaks down macromolecules.
  • Significance: cellular trash/ recyclers and programmed cell death (apoptosis) involvement.
• 40) Microscope — a laboratory instrument that allows scientists to observe objects too small to be seen by the naked eye, by magnifying the image using lenses to bend light and make the object appear larger.
  • Key concepts: resolution, magnification, contrast.
  • Significance: essential tool for cell biology and histology.
• 41) Mitochondria — cellular organelles responsible for carrying out cellular respiration, resulting in the production of ATP, the cell’s main energy-carrying molecule.
  • Key concepts: double membrane; own DNA; powerhouse of the cell.
  • Significance: generates most cellular ATP via oxidative phosphorylation.
• 42) Necrosis — (definition not provided in transcript).
  • Note: Necrosis generally refers to uncontrolled cell death due to injury; not defined in the provided material.
• 43) Nuclear Envelope — double-membrane structure that constitutes the outermost portion of the nucleus.
  • Key concepts: separates nucleoplasm from cytoplasm; contains nuclear pores.
  • Significance: regulates transport of RNA and proteins between nucleus and cytoplasm.
• 44) Nuclear Pores — small channels in the nuclear membrane that facilitate the selective and directional transport of RNA and proteins between the nucleoplasm and the cytoplasm of the cell.
  • Key concepts: selective transport; regulate traffic.
  • Significance: essential for gene expression and nuclear-cytoplasmic communication.
• 45) Nucleus — cell organelle that houses the cell’s DNA and directs the synthesis of ribosomes and proteins.
  • Key concepts: genetic control center; contains nucleolus.
  • Significance: coordinates growth, metabolism, and reproduction.
• 46) Organelle — compartment or sac within a cell.
  • Key concepts: discrete functional units.
  • Significance: enables specialized reactions and processes.
• 47) Osmolarity — total amount of solutes dissolved in a specific amount of solution; concentration.
  • Key concepts: measure of solute concentration.
  • Significance: affects osmosis, water movement, and cell volume.
• 48) Osmoregulation — regulation of solute concentrations and water balance by a cell or organism.
  • Key concepts: maintains internal solute and water balance.
  • Significance: critical for cell function and organismal homeostasis.
• 49) Osmosis — transport of water through a semi permeable membrane according to the concentration gradient of water across the membrane that results from the presence of solute that cannot pass through the membrane.
  • Key concepts: water movement driven by solute differences.
  • Significance: maintains cellular turgor and volume.
• 50) Passive Transport — method of transporting material through a membrane that does not require energy.
  • Key concepts: diffusion, facilitated diffusion, and osmosis.
  • Significance: enables rapid, energy-efficient movement of substances down their gradients.

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• 51) Peripheral Protein — protein found at the surface of a plasma membrane either on its exterior or interior side.
  • Key concepts: associated with membrane surface; can be enzymes or signaling molecules.
  • Significance: participate in signaling, cytoskeletal attachment, and transport regulation.
• 52) Phagocytosis — form of endocytosis that involves the intake of large particles (microorganisms or dead cells) from the extracellular fluid; “cell eating.”
  • Key concepts: engulfment of large particles via vesicles.
  • Significance: essential for immune defense and removal of debris.
• 53) Phospholipid Bilayer — double layer of phospholipid molecules that form the primary structure of a cell membrane, where the hydrophobic tails of the phospholipids face inwards, and the hydrophilic heads face outwards, creating a barrier that separates the cell's interior from its external environment.
  • Key concepts: amphipathic nature; provides barrier and matrix for proteins.
  • Significance: fundamental architecture of all cellular membranes.
• 54) Pinocytosis — form of endocytosis that involves the intake of solutes and fluid from the extracellular fluid; “cell drinking.”
  • Key concepts: uptake of liquids and dissolved solutes.
  • Significance: contributes to nutrient uptake and membrane turnover.
• 55) Plasmodesmata — channel that passes between the cell walls of adjacent plant cells, connects their cytoplasm and allows materials to be transported from cell to cell.
  • Key concepts: cytoplasmic channels through cell walls.
  • Significance: enables intercellular communication and transport in plants.
• 56) Plasmolysis — detaching of the cell membrane from the cell wall and constriction of the cell membrane when a plant cell is in a hypertonic solution.
  • Key concepts: loss of turgor pressure; membrane pulls away from wall.
  • Significance: indicator of hypertonic stress in plant cells.
• 57) Pressure Potential — a component of water potential that consists of the physical pressure on a solution, which can be positive, zero, or negative.
  • Key concepts: part of the water potential equation.
  • Significance: influences water movement in plants and cells.
• 58) Prokaryotic Cell — cell that lacks a nucleus and other membrane-bound organelles.
  • Key concepts: simpler internal organization; often smaller.
  • Significance: represents the most ancient cell type; includes bacteria and archaea.
• 59) Ribosome — cellular structure that carries out protein synthesis, composed of rRNA.
  • Key concepts: small and large subunits; sites for translation.
  • Significance: essential for gene expression and proteome production.
• 60) Rough ER — region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification and phospholipid synthesis.
  • Key concepts: protein synthesis with ribosomes; lipid-related synthesis occurs here.
  • Significance: links protein production to processing and sorting.
• 61) SA:V Ratio — the mathematical calculation of a cell's surface area divided by its volume.
  • Key concepts: higher SA:V supports exchange with surroundings; important for cell size constraints.
  • Significance: influences rates of diffusion and metabolic efficiency.
  • Formula: SA:V = rac{SurfaceArea}{Volume}
• 62) Selectively Permeable — characteristic of a membrane that allows some substances through but not others (also known as semi permeable).
  • Key concepts: selective transport; relies on membrane properties and transport proteins.
  • Significance: enables controlled exchange and homeostasis.
• 63) Smooth ER — region of the endoplasmic reticulum that has few or no ribosomes on its cytoplasmic surface and synthesizes carbohydrates, lipids, and steroid hormones; detoxifies certain chemicals (like pesticides, preservatives, medications, and environmental pollutants) and stores calcium ions.
  • Key concepts: lipid synthesis, carbohydrate metabolism, detoxification, calcium storage.
  • Significance: contributes to membrane production and cellular detox/dosage regulation.
• 64) Sodium Potassium Pump — a major ion pump that maintains essential gradients by transporting Na+ and K+ across the plasma membrane using energy.
  • Key concepts: electrogenic pump; maintains resting membrane potential.
  • Significance: critical for nerve impulse transmission, muscle contraction, and cell volume regulation.
• 65) Solute — repeat from Unit 1.
  • Note: Solutes are dissolved particles affecting osmotic and chemical gradients.
• 66) Solute Potential — a component of water potential that is proportional to the molarity of a solution and that measures the effect of solutes on the direction of water movement; can be zero or negative.
  • Key concepts: also called osmotic potential; decreases as solute concentration increases.
  • Significance: helps predict water movement in osmosis.
• 67) Solution — repeat from Unit 1.
• 68) Solvent — repeat from Unit 1.

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• 69) Subcellular Components — the individual structures within a cell, like organelles, that perform specific functions.
  • Key concepts: discrete functional units.
  • Significance: enable complex cellular activities through specialization.
• 70) Tonicity — amount of solute in a solution.
  • Key concepts: relates to osmolarity and water movement.
  • Significance: helps determine cell response in different solutions (hypertonic, isotonic, hypotonic).
• 71) Turgor Pressure — the force directed against a plant cell wall after the influx of water and swelling of the cell due to osmosis.
  • Key concepts: hydrostatic pressure within plant cells.
  • Significance: maintains rigidity in non-woody tissues and supports plant structure.
• 72) Vacuole — membrane-bound sac, somewhat larger than a vesicle, which functions in cellular storage and transport.
  • Key concepts: storage of water, nutrients, waste.
  • Significance: in plants, central vacuole also helps maintain turgor pressure.
• 73) Vesicle — small membrane-bound sac that functions in cellular storage and transport; its membrane is capable of fusing with the plasma membrane of the endoplasmic reticulum and Golgi apparatus.
  • Key concepts: vesicular trafficking.
  • Significance: mediates transport between organelles and to/from the plasma membrane.
• 74) Water Potential — the potential energy of a water solution per unit volume in relation to pure water at atmospheric pressure and ambient temperature.
  • Key concepts: combines solute potential and pressure potential to predict water movement.
  • Significance: central to understanding osmosis and plant water relations.